Table of Contents Emissions Management Subject Page Introduction .5 OBD History.5 OBD I.6 OBD II .6 Objectives of OBD II.6 Emissions Overview .7 Purpose of the System.7 What is OBD? .7 What happens if a problem is detected?.7 What is the most common problem detected by OBD? .8 Fuel Filler Cap.8 Misfire Detection.8 Engine Misfire Diagnosis .9 Ignition System.9 Engine Mechanical Systems.10 Fuel Quality, Delivery, Injection & EVAPORATIVE Systems .10 Implausible ECM Control Function or Sensor Input Signals .11 Misfire Detection.12 Overview of the National Low Emission Vehicle Program.13 Emission Reduction Stages .13 BMW SULEV & PZEV Engines .14 BMW M56 Engine.14 BMW N51 Engine .15 Catalytic Converters.16 Oxygen Sensors.16 Fuel Pump System .16 Fuel Injectors.16 Secondary Air System .16 Fuel System .17 Cooling System .17 Initial Print Date: 03/11 Revision Date: Subject Page System Monitoring .18 Permanent Monitoring.18 Cyclic Monitoring .18 Drive Cycle.19 Readiness Code.22 Readiness Code using the ISTA .22 OBD II Diagnostic Trouble Codes (DTC).23 BMW Fault Code .24 OBD II Fault Memory and Fault Codes.24 Emission Control Function Monitoring & Comprehensive Component Monitoring.25 OBD II System Information on TIS .26 Scan Tool Connection .27 16 Pin Diagnostic Socket .28 BoardNet 2020 .29 Emission Management.30 Malfunction Indicator Light (MIL) .30 Evaporative Emissions.32 Exhaust Emissions .32 Adaptation Values.33 Oxygen Sensors .34 Oxygen sensor before catalytic converter.34 Bosch LSH25 Oxygen Sensor .34 Bosch LSU Planar Wideband Oxygen Sensor.36 Bosch LSU ADV (Planar Wideband).37 Oxygen Sensor after Catalytic Converter .37 Oxygen Sensor Signals.38 Direct Oxygen Sensor Heating .39 Testing the Oxygen Sensor .40 Catalytic Converter Monitoring.41 On-Board Refueling Vapor Recovery (ORVR) E9x Vehicles.44 Ventilation During Engine Operation .45 Evaporative Leakage Detection (DM-TL).46 Test Results .48 Principle of Operation .50 PHASE 1 - Reference Measurement.50 PHASE 2 - Leak Detection .51 Evaporative Emission Purging.52 Subject Page Carbon Canister.53 Evaporative Emission Valve.53 Secondary Air Injection .54 Secondary Air Injection Monitoring .55 Secondary Air System.55 Secondary air pump.55 Secondary air valve .56 On-board diagnosis of secondary air system.56 Misfire Detection.57 Emission Increase .57 Catalyst Damage .57 Ambient Barometric Pressure.58 Crankcase Ventilation.59 Crankcase Ventilation (N51 and N52KP) .60 Crankcase Ventilation (N54).61 Crankcase Ventilation System Overview (N55) .63 Naturally Aspirated Mode (N55) .63 Boost Mode (N55).63 Crankcase Ventilation System Overview (N54) .69 Naturally Aspirated Mode (N54) .69 Boost Mode (N54).69 Crankcase Ventilation Heating .74 Emissions Management Model: All Equipped with OBD II Production: 1995 to Present Manufacturer: Bosch and Siemens Engine Control Modules After completion of this module you will be able to: • Describe what is required to illuminate the Malfunction Indicator Lamp • Access readiness codes using the ISID • Understand how a oxygen sensor operates • Understand how the DM-TL system operates • Test a DM-TL system using a smoke tester • Understand how misfire monitoring takes place 4 Emissions Management Introduction OBD History As a result of low fuel costs, together with a high standard of living and a dense popula¬ tion, the state of California was affected particularly heavily by air pollution. This spurred the state to pass the most comprehensive and stringent emissions and consumption laws in the world. The automobile manufacturers were reminded of their obligations and this drove them on to comply with the new regulations at enormous expense. • In continuing efforts to improve air quality, the Environmental Protection Agency (EPA) amended the Clean Air Act in 1990. The Clean Air Act was originally mandat¬ ed in 1970. The Clean Air Act has a direct impact on automobile manufactures whereby they are responsible to comply with the regulations set forth by the EPA. The 1990 amendment of the Clean Air Act set forth all of the changes currently being introduced on vehicles sold in the United States today. • In 1967, the State of California formed the California Air Resources Board (CARB) to develop and carryout air quality improvement programs for California’s unique air pollution conditions. Through the years, CARB programs have evolved into what we now know as ON Board Diagnostics and the National Low Emission Vehicle Program. • The EPA has adopted many of the CARB programs as National programs and laws. One of these earlier programs was OBD I and the introduction of the “Check Engine” Light. • BMW first introduced OBD I and the check engine light in the 1987 model year. This enhanced diagnosis through the display of “flash codes” using the check engine light as well as the BMW 2013 and GT-1. OBD I was only the first step in an ongoing effort to monitor and reduce tailpipe emissions. • By the 1989 model year all automotive manufactures had to assure that all individ¬ ual components influencing the composition of exhaust emissions would be electri¬ cally monitored and that the driver be informed whenever such a component failed. • Since the 1996 model year all vehicles must comply with OBD II requirements. OBD II requires the monitoring of virtually every component that can affect the emission performance of a vehicle plus store the associated fault code and condi¬ tion in memory. If a problem is detected and then re-detected during a later drive cycle more than one time, the OBD II system must also illuminate the “Check Engine” Light in the instrument cluster to alert the driver that a malfunction has occurred. However, the flash code function of the Check Engine Light in OBD I vehicles is not a function in OBD II vehicles. 5 Emissions Management • This requirement is carried out by the Engine Control Module (ECM/DME) as well as the Automatic Transmission Control Module (EGS/AGS) and the Electronic Throttle Control Module (EML) to monitor and store faults associated with all com¬ ponents/systems that can influence exhaust and evaporative emissions. OBD I The essential elements here are that electrical components which affect exhaust emis¬ sions are monitored by the motor-electronics system and an optical warning signal (CHECK ENGINE Light) is issued in the event of an OBD l-relevant malfunction. The cor¬ responding fault can be read out via a flashing code without the aid of a testing device. OBD II Since January 1996, OBD II has been compulsory on all vehicles in the US market. The main difference from OBD I is that not only are the purely electrical components moni¬ tored but also all the systems and processes that affect exhaust emissions and fuel sys¬ tem evaporative emissions. The operational reliability of the exhaust-treatment system must be guaranteed for 5 years and/or 100,000 miles; this is maintained by emission certification. In this case, the data relevant to exhaust/evaporative emissions are read out via a standardized interface with a universal "diagnosis device". If a violation is identified, the vehicle manufacturer in question is legally bound to eliminate the fault throughout the entire vehicle series. Objectives of OBD II • Permanent monitoring of components relevant to exhaust emissions in all vehicles. • Immediate detection and indication of significant emission increases over the entire service life of each vehicle. • Permanently low exhaust emissions in the field. 6 Emissions Management Emissions Overview Purpose of the System What is OBD? Today many of the engine’s control systems such as throttle opening, fuel injection, ignition, emissions and performance are controlled by an electronic control module and the related sensors and actuators. The first on-board diagnostic (OBD) systems were developed by the manufacturer as a way to detect problems with the electronic sys¬ tems. Beginning with 1994 model year, requirements for OBD systems have been established by the EPA and CARB. The purpose of the OBD system is to assure proper emission control system operation for the vehicle’s lifetime by monitoring emission-related com¬ ponents and systems for deterioration and malfunction. This includes also a check of the tank ventilation system for vapor leaks. The OBD system consists of the engine and transmission control modules, their sen¬ sors and actuators along with the diagnostic software. The control modules can detect system problems even before the driver notices a driveability problem because many problems that affect emissions can be electrical or even chemical in nature. What happens if a problem is detected? When the OBD system determines that a problem exists, a corresponding “Diagnostic Trouble Code” is stored in the control mod¬ ule’s memory. The control module also illuminates a yellow dashboard Malfunction Indicator Light indicat¬ ing “Check Engine” or “Service Engine Soon” or displays an engine symbol. This light informs the driver of the need for service, NOT of the need to stop the vehicle. A blinking or flashing dashboard light indicates a rather severe level of engine misfire. After fixing the problem the Fault code is deleted to turn off the light. If the conditions that caused a problem are no longer present the vehicle’s OBD system can turn off the dashboard light automatically. If the OBD system evaluates the component or system three consecutive times and no longer detects the initial problem, the dashboard light will turn off automatically. Have you seen this light? A short introduction to OBD 7 Emissions Management What is the most common problem detected by OBD? Fuel Filler Cap If the fuel filler cap is not properly closed after refueling, the OBD system will detect the vapor leak that exists from the cap not being completely tightened. If you tighten the cap subsequently, the dashboard light should be extinguished within a few days or after deleting the Fault code. This is not an indication of a faulty OBD sys¬ tem. The OBD system has properly diagnosed the problem and accordingly alerted the driver by illuminating the dashboard light. Please check the fuel filler cap first when the dashboard light comes on to avoid unnec¬ essary diagnostic time. To check the fuel filler cap turn the cap to the right until you hear a click or the cap reaches the full stop. Make sure that the retaining strap is not caught between the filler pipe and the fuel filler cap. If the light should stay on further in depth evaporative leak diagnosis is required. Misfire Detection As part of the CARB/OBD II regulations the Engine Control Module must determine if misfire is occurring and also identify the specific cylinder(s). The ECM will determine severity of the misfire event, and whether it is emissions relevant or catalyst damaging (more information is available in the Emission Management section). In order to accom¬ plish these tasks the ECM monitors the crankshaft for acceleration losses during firing segments of cylinder specific firing order. If the signal is implausible an erroneous refer¬ ence mark can be obtained by the ECM which will result in a misfire fault being set. Possible causes of cylinder misfire faults (actual field findings): • Vehicle ran low or out of fuel • Poor fuel quality (ex. water in fuel, customer uses an additive, etc.) • Low/high fuel pressure • Ignition coil • Fouled spark plug(s) • Restricted / contaminated fuel injector(s) • Crankshaft position sensor • Poor combustion due to low compression or high leakage • Blocked/restricted Catalyst 8 Emissions Management Engine Misfire Diagnosis Engine Misfire is the result of inefficient combustion in one or more cylinders. The caus¬ es of Engine Misfire are extensive but can be grouped into the following sub-systems. Consider the charts below as an additional diagnostic aid once ISTA is connected, the correct fault symptom has been chosen and the fault memory has been interrogated. Follow the Test Module as displayed by ISTA. IGNITION SYSTEM COMPONENT POSSIBLE CONDITION TEST CORRECTION Spark Plug: • Incorrect spark plug installed • Electrode gap closed or too small • Electrode(s) missing • Oil or fuel fouled spark plug • Ceramic insulation cracked Secondary • Verify correct spark plug Ignition • Replace if necessary • Swap with another cylinder Secondary • Wet or moist due to water infiltration, circuit: (wiring,* High resistance due to corrosion. M73-cap, rotor) • Check water ingress, repair, replace • Check resistance value, replace Ignition Coil(s): • Secondary/Primary Circuits open or shorted. Secondary • Housing cracked, damaged. and Primary • Inspect and replace if necessary • Swap with another cylinder Ignition Coil & Engine Harness Connectors • Power supply, Primary control and Primary • Look for open, loose connector, ground (shunt signal) circuits impaired. Ignition & corrosion, crossed or backed out Term 4A feed- pins (also consider ignition unloader or back Preset ECM relay on MY97 and newer cars). Measurements • Determine defective condition, repair or replace. • A secondary ignition oscilloscope display provides vital information about the ignition system’s condition. • Follow the precautions in group 12 of the Repair Instructions. • Use the following scope patterns as a guideline for ignition system diagnosis. F+ f i' V J* I - ■ IrrM V: W. a: ■ Iff- i «ih VI »»*?■ ^ >* • 1 Hh| I w kjii ■.■»■■■« 9 w>ch mmh, bi-hv^i r*d iwfc-r-a »«--** kiwq LK/rtV HI H'JVFf FK 'IlHfFK WnnHI b-Tv L".■V-L-V 1 -n F-i L-.r.r-Fa O.u.% IFA Ji,. Hr —r >>r 1 BOTTOMS IMM friWI :jarv vaunmn ira twi l-ii,4 — 1 - T ■ ■ Y T - - -1 — L - tm — taH k, j -nkJ "bi ij. I id f Ai ud rid -BB La uju^Mia f waJ u isufii ■ A- unt^wTihniurn^ k i I hi! cl-rr^A I i-bbj idb- ’M m ■ iB ^ ir. rflhr iwt k l FH5-11 wv?. Evaluation of secondary signal amplitude at idle speed. 1. Normal Ignition Voltage Peak: Spark Plug is OK 2. Low Ignition Voltage Peak: Gap too small (defective) 3. High Ignition voltage peak: Gap too large (defective) 0 0 © © © NORMAL COMBUSTION PERIOD ONG COMBUSTION - PERIOD (SMALL GAP) ■‘Him m in*/L I HORT COMBUSTION PERIOD (LARGE GAP) 9 Emissions Management ENGINE MECHANICAL SYSTEMS COMPONENT POSSIBLE CONDITION TEST CORRECTION Pistons, • Hole in piston crown, ring(s) broken, • Idle Quality - Rough Run- • Correct condition as Rings, valve(s) not seating, valve(s) bent, ning Preset. required. Valves, valve spring(s) broken, camshaft lobe • Cylinder compression & Camshaft: cracked, etc. leakdown tests. Hydraulic • HVA oil bore restricted or blocked. • Idle Quality - Rough Run- • Always consider Valve • Engine oil pressure builds up too slow. ning Preset. mechanical com- Actuator * Intermittent Misfire Fault - Not • Listen to HVA ponents when (HVA): Currently Present. • Check Oil Pressure diagnosing misfire. • HVA binding/sticking in bore. • Cylinder leakdown • Inspect for scoring. Vacuum • Unmetered vacuum leaks causing a • Idle Quality - Rough Run- • Correct condition as Leaks: “lean” operating condition. Possible ning Preset. Test for vacuum required. “Excessive Mixture Deviation” leaks per Repair Instr. and SIB fault codes. on “Crankcase Ventilation”. ■ • Interpret Add. & Multiple adaptation values FUEL QUALITY, DELIVERY, INJECTION & EVAPORATIVE SYSTEMS COMPONENT POSSIBLE CONDITION TEST CORRECTION Fuel (quality): • Contaminated fuel. • Clean fuel system, replace fuel. (water, other non combustible). Fuel Delivery: • Fuel pump delivery pressure low, restriction in fuel line to fuel rail or running loss valve. • Fuel filter restricted (clogged). • Low fuel in tank. • Check fuel pressure & volume. • Check fuel pump power and ground • Determine restriction/flow reduction, replace component as necessary. • Interpret Additive and Multiplicative adaptation values. Running Loss • Valve stuck in “small circuit” position. Valve: • Check valve • Display “diagnosis requests” in ISTA and test valve for proper function, repl¬ ace valve as necessary. Fuel Injectors: Leaking fuel injector pintle seats cause rich engine starts with hot ambient temperatures. Blocked (dirty) injector(s). • Ti Preset & • Check injectors for leakage, status page. • Swap suspect injector with another • Sec Ign scope cylinder, pattern. • Inspect injector, replace if necessary. Fuel Pressure • Regulator defective, causes fluctuation Regulator: in the injected quantity of fuel causing mixture adaptation faults. • Fuel pressure • Check nominal fuel pressure value with engine operating under varied speeds. Evaporative • Defective evaporative system vent System: causing fuel tank collapse and fuel. starvation. • ISTA status, Evap test with press¬ ure tool, purge valve func. test. • Check the fuel tank condition and vent line. • Check Fresh Air Valve on TLEV E36 vehicles or LDP/ DM-TL and filter on ORVR vehicles for proper system “breathing”. 10 Emissions Management IMPLAUSIBLE ECM CONTROL FUNCTION OR SENSOR INPUT SIGNALS COMPONENT POSSIBLE CONDITION TEST CORRECTION Crankshaft Position Sensor or Increment Wheel: • Implausible signal for misfire detection. • ISTA preset • Increment wheel loose or damaged measurement, (internal on M44, M52 and M54, external on M62 & M73). • Air gap between sensor and wheel. • Noticeable at higher rpm. • Determine defective sensor or increment wheel and replace. Catalyst • Excessive exhaust back pressure Damaged: (bank specific fault present, more noticeable under heavy load and high rpm). • ISTA preset • Determine catalyst condition, replace measurement or repair as necessary. of oxygen sensor. • Back pressure test per SIB with Special Tool. Oxygen • Excessive mixture deviation, Sensor: possible vacuum leaks. • Monitor oxygen sensor signal via ISTA/IMIB. • Swap sensor from other bank (if app¬ licable) and see if fault transfers to other bank. Engine • Internal control module fault. Control Module • Misfire Reprogramming. • Check fault • Highly unlikely but must be considered, memory. • Refer to SIB • Check Model/Prod range - reprogram When diagnosing a Misfire fault code, Remember: “Misfire” is caused by a defect in the internal combustion engine or a defect in the control of the engine operation. “Misfire” is the result of improper combustion (variation between cylinders) as measured at the crankshaft due to: - Engine mechanical defects; breakage, wear, leakage or improper tolerances. - Excessive mixture deviation; air (vacuum leaks), fuel and all the components that deliver air/fuel into the combustion chambers. - Faulty ignition; primary, secondary including spark plugs. - Faulty exhaust flow; affecting back pressure. - Tolerance parameters; ECM programming. A Misfire fault code(s) is the “symptom” of a faulty input for proper combustion. When diagnosing a misfire, review the charts to assist you in finding the faulty input. 11 Emissions Management Misfire Detection As part of the OBD II regulations the ECM must determine misfire and also identify the specific cylin¬ ders), the severity of the misfire and whether it is emissions rele¬ vant or catalyst damaging based on monitoring crankshaft acceler¬ ation. In order to accomplish these tasks the ECM monitors the crankshaft for acceleration by the impulse wheel segments of cylinder spe¬ cific firing order. The misfire/engine roughness calcula¬ tion is derived from the differ¬ ences in the period duration of individual increment gear seg¬ ments. Each segment period consist of an angular range of 90° crank angle that starts 54° before Top Dead Center. SMOOTH RUNNING ENGINE ENGINE MISFIRE DETECTED (NOTE SQUARE WAVE SIGNAL) If the expected period duration is greater than the permissible value a misfire fault for the particular cylinder is stored in the fault memory of the ECM. Depending on the level of misfire rate measured the ECM will illuminate the "Malfunction Indicator Light”, deactivate the specific fuel injector to the particular cylinder and switch oxygen sensor control to open-loop. In order to eliminate misfire faults that can occur as a result of varying flywheel toler¬ ances (manufacturing process) an internal adaptation of the flywheel is made. The adap¬ tation is made during periods of decel fuel cut-off in order to avoid any rotational irregu¬ larities which the engine can cause during combustion. This adaptation is used to cor¬ rect segment duration periods prior to evaluation for a misfire event. If the sensor wheel adaptation has not been completed the misfire thresholds are limited to engine speed dependent values only and misfire detection is less sensitive. The crankshaft sensor adaptation is stored internally and is not displayed via ISTA. If the adaptation limit is exceeded a fault will be set. 12 Emissions Management Overview of the National Low Emission Vehicle Program Emission Reduction Stages While OBDII has the function of monitoring for emission related faults and alerting the operator of the vehicle, the National Low Emission Vehicle Program reguires a certain number of vehicles produced (specific to manufacturing totals) currently comply with the following emission stages; TLEV: Transitional Low Emission Vehicle LEV: Low Emission Vehicle ULEV: Ultra Low Emission Vehicle. SULEV Super Ultra Low Emission Vehicle Prior to the National Low Emission Vehicle Program, the most stringent exhaust reduc¬ tion compliancy is what is known internally within BMW as HC II. The benefit of exhaust emission reductions that the National Low Emission Vehicle Program provides com¬ pared with the HC II standard is as follows; TLEV: 50% cleaner LEV: 70% cleaner ULEV: 84% cleaner SULEV 90% cleaner Grams/Mile @ 50° F - Cold Engine Startup Compliance Level NMHC Non-Methane Hydrocarbon CO Carbon Monoxide NOx Oxide(s) of Nitrogen TLEV 0.250 3.4 0.4 LEV 0.131 3.4 0.2 ULEV 0.040 1.7 0.2 Grams/Mile @ 50,000 miles Compliance Level NMHC Non-Methane Hydrocarbon CO Carbon Monoxide NOx Oxide(s) of Nitrogen TLEV 0.125 3.4 0.4 LEV 0.075 3.4 0.2 ULEV 0.040 1.7 0.2 Grams/Mile @ 100,000 miles Compliance Level NMHC Non-Methane Hydrocarbon CO Carbon Monoxide NOx Oxide(s) of Nitrogen TLEV 0.156 4.2 0.6 LEV 0.090 4.2 0.3 ULEV 0.055 2.1 0.3 13 Emissions Management PZEV regulations include: • Vehicles must meet SULEV tailpipe emissions standard (approx. 1/5 of ULEV stan¬ dards) • Vehicles conform to Zero Evaporative Emissions • Vehicles subject to extended OBD regulations. • Emission relevant components warrantied for 15 years or 150,000 miles BMW SULEV & PZEV Engines BMW M56 Engine The following components are used to achieve SULEV (Super Ultra Low Emission Vehicle) and ZEV Zero Evaporative Emission requirements: • Pistons - Revised to change spark travel path • Catalytic Converters - Ceramic carriers with high cell density for better “Warm Up” Control • Oxygen Sensors - Planar wide band O 2 sensors in front of the cats • Vanos - Positioning changed during start up for improved start up and emissions • Fuel Pump Control - Revised with raised pressure and more accurate flow control • Fuel Injectors - New design for improved fuel flow and higher working pressure • Fuel System - All metal fuel system components made of stainless steel • Air Intake System - Revised to block HC escape • Crankcase Ventilation - Revised • Secondary Air System - Mass air flow sensor to monitor secondary air flow • Cooling System - Revised to reduce Ozone levels 14 Emissions Management BMW N51 Engine In order to comply with SULEV requirements, the N51 is another variant of the N52 engine. There are various measures to meet the EPA/CARB standards, some of which are familiar from the previous SULEV (M56) engine. Some of the SULEV measures for the N51 include: • Near engine catalyst with additional underbody catalyst • Secondary air system • Optimized combustion chamber geometry in cylinder head • Modified piston crown for lower compression • Plastic valve cover with integrated crankcase vent valve and separator (from N52KP) • Stainless steel fuel lines with threaded connections • Radiator with “Prem-air” coating • Throttle system - EGAS08 carried over from N52KP • Airbox with Activated carbon filter for EVAP control • Purge system pipes are made from “optimized” plastic 15 Emissions Management Catalytic Converters The catalysts attached in direct proximity to the engine and are equipped with ceramic(s) carriers in high cell density technology. These converters reach operating temperature faster and offer quicker control of exhaust emissions. Vehicles are also equipped with dual downstream converters. Oxygen Sensors The M56 engine use for Oxygen sensors, two planar broadband sensors upstream of the converter and two sensors downstream. The planar broadband sensor reach operating temperature very fast and are able to effect fuel mixtures in approximately 5 seconds. Fuel Pump System Fuel system operating pressure is increased to 5 Bar. The fuel pump is controlled by the Fuel pump control unit, based on engine demand as received from the DME over the Lo-CAN. The fuel pump control unit additionally receives information over the K-Bus, specifically crash information from the MRS. Fuel Injectors Nozzle diameter of the fuel injectors has been reduced and the installation angle has been changed. The injec¬ tors were also adapted to perform at the higher system operating pressure. Injectors screw into the rail and a tap to test pressure readings is NOT provided. Secondary Air System The secondary air pump has been revised to improve its response time in cold weather starting situations. A HFM (Hot Film Air Mass Meter) has been added to the secondary air system to monitor air volume pumped into the exhaust for more accurate control of the NOx emissions. 16 Emissions Management Fuel System In order to meet the Zero Evaporative Emission requirement, the fuel system was completely revised. The fuel tank, tank filler neck, charcoal canister, fuel rail and tank ventilation valve are all made of stainless steel. When perform repairs on the fuel system, it is imperative that all fitting remain clean and that the proper tightening torques are observed. The fuel tank is manufactured of high grade steel and completely coated to meet the requirements of a minimum durability of 15 years. The fuel tank can be exchanged only as a complete unit. Index Explanation 1 Syphon Jet 2 Roll over valve 3 Fuel Filter 4 Electric fuel pump 5 Liquid Vapor Separator Cooling System The radiator of SULEV looks similar to the standard radiator. The surface of the cooling fins are coated with a special “PremAir” coating. The coating consists of multiple porous layers of a catalytic surface. The task of the catalyst coating is to convert Ozone into Oxygen. 17 Emissions Management System Monitoring Within the framework of OBD II, certain components/systems must be monitored once per driving cycle while other control systems (e.g. misfire detection) must be monitored permanently. A "driving cycle" consists of engine startup, vehicle operation (exceeding of starting speed), coasting and engine stopping. Permanent Monitoring Permanently monitored systems are monitored according to temperature immediately after startup. In the event of malfunctions (e.g. oxygen sensor), the Malfunction Indicator Light will illuminate immediately. The following are monitored permanently: • Misfire Detection • Fuel System (duration of injection) • All emission related electrical circuits, components and systems of the ECM, TCM and EML (if equipped). Cyclic Monitoring Systems monitored once per driving cycle will only result in a fault being registered after the corresponding operating conditions have been completed. Therefore, there is no possibility for checking when the engine is started up briefly and then shut down. The following are monitored once per driving cycle: • Oxygen Sensor Function • Secondary Air Injection System • Catalytic Converter Function (efficiency) • Evaporative Vapor Recovery System Due to the complexity involved in meeting the test criteria within the defined driving cycle, all tests may not be completed within one "customer driving cycle". The test can be successfully completed within the defined criteria, however customer driving styles may differ and therefore may not always monitor all involved components/systems in one "trip". 18 Emissions Management Drive Cycle The following diagram shows how a drive cycle is set (test drive) in order for all the sys¬ tems to be monitored once. The test conditions can be created in any desired order after startup. Vehicle Speed Example of a Drive Cycle for Completing all OBD II Relevant Checks: 1. Engine cold start, idling, approximately 3 minutes. Evaluated: • Secondary Air System • Evaporative Leak Detection (LDP Equipped Vehicles) 2. Constant driving at 20 to 30 MPH, approximately 4 minutes. Evaluated: • Oxygen Sensors - Achieved “Closed Loop” Operation • Oxygen Sensors - Response Time and Switching Time (Control Frequency) 3. Constant driving at 40 to 60 MPH, approximately 15 minutes (sufficient vehicle coast¬ ing phases included). Evaluated: • Catalytic Converter Efficiency • Oxygen Sensors - Response Time and Switching Time (Control Frequency) 4. Engine idling, approximately 5 minutes. Evaluated: • Tank-Leak Diagnosis ( DM-TL Equipped Vehicles after KL 15 is switched OFF) The diagnostic sequence illustrated above will be interrupted if: ? \ * The engine speed exceeds 3000 RPM — • Large fluctuations in the accelerator pedal position. • The driving speed exceeds 60 MPH 19 Emissions Management The “Malfunction Indicator Light” (MIL) will be illuminated under the following conditions: • Upon the completion of the next con¬ secutive driving cycle where the previ¬ ously faulted system is monitored again and the emissions relevant fault is again present. • Immediately if a “Catalyst Damaging” fault occurs (Misfire Detection). Monitored Components Malfunction Indicator Light The illumination of the light is performed in accordance with the Federal Test Procedure (FTP) which requires the lamp to be illuminated when: • A malfunction of a component that can affect the emission performance of the vehicle occurs and causes emissions to exceed 1.5 times the standards required by the (FTP). • Manufacturer-defined specifications are exceeded. • An implausible input signal is generated. • Catalyst deterioration causes HC-emissions to exceed a limit equivalent to 1.5 times the standard (FTP). • Misfire faults occur. • A leak is detected in the evaporative system, or “purging” is defective. • ECM fails to enter closed-loop oxygen sensor control operation within a specified time interval. • Engine control or automatic transmission control enters a "limp home" operating mode. • Ignition is on (KL15) position before cranking = Bulb Check Function. Within the BMW system the illumination of the Malfunction Indicator Light is performed in accordance with the regulations set forth in CARB mail-out 1968.1 and as demon¬ strated via the Federal Test Procedure (FTP). The following page provides several exam¬ ples of when and how the Malfunction Indicator Light is illuminated based on the "cus¬ tomer drive cycle". 20 Emissions Management DRIVE CYCLE # 1 DRIVE CYCLE # 2 DRIVE CYCLE # 3 DRIVE CYCLE # 4 DRIVE CYCLE # 5 i * DRIVE CYCLE # 43 TEXT NO. FUNCTION CHECKED FAULT CODE SET MIL STATUS FUNCTION CHECKED FAULT CODE SET MIL STATUS FUNCTION CHECKED FAULT CODE SET MIL STATUS FUNCTION CHECKED FAULT CODE SET MIL STATUS FUNCTION CHECKED FAULT CODE SET MIL STATUS FUNCTION CHECKED FAULT CODE ERASED MIL STATUS CHECK ENGINE CHECK ENGINE CHECK ENGINE CHECK ENGINE CHECK ENGINE CHECK ENGINE 1. YES YES OFF 2. YES YES OFF YES YES ON 3. YES YES OFF NO NO OFF YES YES ON 4. YES YES OFF YES NO OFF YES NO OFF YES YES OFF YES YES ON L_ 5. YES YES OFF YES YES ON YES NO ON YES NO ON YES NO OFF \ 1 k_ r / 6. YES YES OFF YES YES ON YES NO ON YES NO ON YES NO OFF YES ''fault/ CODE ERASED €. - V OFF 1. A fault code is stored within the ECM upon the first occurrence of a fault in the sys¬ tem being checked. 2. The "Malfunction Indicator Light” will not be illuminated until the completion of the second consecutive "customer driving cycle" where the previously faulted system is again monitored and a fault is still present or a catalyst damaging fault has occurred. 3. If the second drive cycle was not complete and the specific function was not checked as shown in the example, the ECM counts the third drive cycle as the “next consecu¬ tive" drive cycle. The "Malfunction Indicator Light” is illuminated if the function is checked and the fault is still present. 4. If there is an intermittent fault present and does not cause a fault to be set through multiple drive cycles, two complete consecutive drive cycles with the fault present are required for the "Malfunction Indicator Light” to be illuminated. 5. Once the "Malfunction Indicator Light” is illuminated it will remain illuminated unless the specific function has been checked without fault through three complete consec¬ utive drive cycles. 6. The fault code will also be cleared from memory automatically if the specific function is checked through 40 consecutive drive cycles without the fault being detected or with the use of either the ISTA and IMIB.. Note: In order to clear a catalyst damaging fault (see Misfire Detection) from memory, the condition must be evaluated for 80 consecutive cycles without the fault reoccurring. With the use of a universal scan tool, connected to the "OBD" DLC an SAE standardized DTC can be obtained, along with the condition associated with the illumination of the "Malfunction Indicator Light”. Using the ISTA, a fault code and the conditions associated with its setting can be obtained prior to the illumination of the "Malfunction Indicator Light”. 21 Emissions Management Readiness Code The readiness code provides status (Yes/No) of the system having completed all the required monitoring functions or not. The readiness code is displayed with an aftermar¬ ket Scan Tool or ISTA. The code is a binary (1/0) indicating; • 0 = Test Not Completed or Not Applicable - six cylinder vehicles (not ready - V8 and VI2) • 1 = Test Completed - six cylinder vehicles (ready - V8 and VI2) A "readiness code" must be stored after any clearing of fault memory or disconnection of the ECM. A readiness code of "0" will be stored (see below) after a complete diag¬ nostic check of all components/systems, that can turn on the "Malfunction Indicator Light” is performed. The readiness code was established to prevent anyone with an emissions related fault and a "Malfunction Indicator Light” on from disconnecting the battery or clearing the fault memory to manipulate the results of the emissions test procedure (IM 240). Interpretation of the Readiness Code by the ECM(s) (SAE J1979) The complete readiness code is equal to "one" byte (eight bits). Every bit represents one complete test and is displayed by the scan tool, as required by CARB/EPA. For example: 0 = EGR Monitoring (=0, N/A with BMW) 1 = Oxygen Sensor Heater Monitoring 1 = Oxygen Sensor Monitoring 0 = Air Condition (=0, N/A with BMW) 1 = Secondary Air Delivery Monitoring 1 = Evaporative System Monitoring 0 = Catalyst Heating 1 = Catalyst Efficiency Monitoring ^IW'tH ow !YMHT fOR * ric-r—jf*. ririY r ;«■ .>■■: ■H r - _ i c mt li-V-lf iJJ-VuL" ODC« « >* fflwliu ur-ajt: I ■rn, .v Drive the car in such a manner that all tests listed above can be completed (refer to the drive cycle). When the complete "readiness code" equals "1" (ready) then all tests have been completed and the system has established its "readiness". Readiness Code using the ISTA The readiness code can be checked with the ISTA. This is particularly helpful in verify¬ ing that “drive cycle” criteria was achieved. A repair can be confirmed before returning the vehicle to the customer by a successfully completed drive cycle. 22 Emissions Management OBD II Diagnostic Trouble Codes (DTC) The Society of Automotive Engineers (SAE) established the Diagnostic Trouble Codes used for OBD II systems (SAE J2012). The DTC’s are designed to be identified by their alpha/numeric structure. The SAE has designated the emission related DTC’s to start with the letter “P” for Powertrain related systems, hence their nickname “P-code”. For example: P 0 4 4 0 P-Powertrain, B-Body, C-Chassis DTC Source; 0-SAE, 1 -BMW- System; 0-Total System- 1- Air/Fuel Induction 2- Fuel Injection 3- Ignition System or Misfire 4- Auxiliary Emission Control 5- Vehicle Speed & Idle Control 6- Control Module Inputs/Outputs 7- Transmission Sequentially numbered fault identifying individual components or circuits (00-99) • DTC’s are stored whenever the "Malfunction Indicator Light” is illuminated. • A requirement of CARB/EPA is providing universal diagnostic access to DTC’s via a standardized Diagnostic Link Connector (DLC) using a standardized tester (scan tool). DTC’s only provide one set of environmental operating conditions when a fault is stored. This single "Freeze Frame" or snapshot refers to a block of the vehicles environmental conditions for a specific time when the fault first occurred. The infor¬ mation which is stored is defined by SAE and is limited in scope. This information may not even be specific to the type of fault. 23 Emissions Management BMW Fault Code • BMW Codes are stored as soon they occur even before the "Malfunction Indicator Light” comes on. • BMW Codes are defined by BMW, Bosch and Siemens Engineers to provide greater detail to fault specific information. • Siemens systems - one set from four fault specific environmental conditions is stored with the first fault occurrence. This information can change and is specific to each fault code to aid in diagnosing. A maximum of ten different faults containing four environmental conditions can be stored. • Bosch systems - a maximum of four sets from three fault specific environmental conditions is stored within each fault code. This information can change and is spe¬ cific to each fault code to aid in diagnosing. A maximum of ten different faults con¬ taining three environmental conditions can be stored. • BMW Codes also store and displays a "time stamp" when the fault last occurred. • A fault gualifier gives more specific detailed information about the type of fault (upper limit, lower limit, disconnection, plausibility, etc.). • BMW Fault Codes will alert the Technician of the current fault status. He/she will be advised if the fault is actually still present, not currently present or intermittent. The fault specific information is stored and accessible through ISTA. • BMW Fault Codes determine the diagnostic output for ISTA. OBD II Fault Memory and Fault Codes Within the framework of OBD II, a diagnosis of all emission-related components/func¬ tions must take place during driving. Faults will be stored and displayed if necessary. For this purpose, the ECM includes OBD II memory. The standardized P codes for malfunctions are stored in this memory. The memory can be read out with the ISTA or a Scantool. 24 Emissions Management Emission Control Function Monitoring & Comprehensive Component Monitoring OBD II regulations are based on section 1968.1 of Title 13, California Code of Regulations (CCR), The law set forth in section 1968.1 requires an increased scope of monitoring emission related control functions including: • Catalyst Monitoring • Heated Catalyst Monitoring (currently used on BMW 750il_ vehicles) • Misfire Monitoring • Evaporative System Monitoring • Secondary Air System Monitoring • Air Conditioning System Refrigerant Monitoring (Not applicable for BMW vehicles) • Fuel System Monitoring • Oxygen Sensor Monitoring • Exhaust Gas Recirculation (EGR) System Monitoring (Not applicable for BMW vehicles) • Positive Crankcase Ventilation (PCV) System Monitoring (Not required at this time) • Thermostat Monitoring (if equipped) Monitoring these emission requirements is a function of the ECM which uses “data sets” while monitoring the conditions of the environment and the operation of the engine using existing input sensors and output actuators. The data sets are programmed reference values the ECM refers to when a specific mon¬ itoring procedure is occurring. If the ECM cannot determine the environmental and/or engine operating conditions due to an impaired or missing signal, it will set a fault and illuminate the “Malfunction Indicator Light”. This input or control signal monitoring falls under another category called “Comprehensive Component Monitoring”. The ECM must recognize the loss or impairment of the signal or component. The ECM determines a faulted signal or sensor via three conditions: 1. Signal or component shorted to ground. 2. Signal or component shorted to B+. 3. Signal or component lost (open circuit). Specific fault codes are used to alert the diagnostician of these conditions. 25 Emissions Management OBD II System Information on TIS BMW TIS includes a section with OBD II related information and it is divided into three main categories: • Mode $06 Interface Data; features a list of current and previous DME’s for specific on board monitoring test results. • OBD II Overview and Drive Cycle; features a brief summary of the Emissions Overview contained in this Reference Manual. • OBD II Systems; features a list of current and previous DME’s with information on Fault Codes Conditions with possible fault causes and suggested repair procedures as well as specific OBD II Description information as per DME version. This section is an important tool that can help you in your diagnosis process! To access the information contained in the OBD section, access CenterNet, then go to TIS and select the category you wish to browse. Umi ► ns o ■ tb.H f, 4J-nil BMW of North America, LLC .Vhlil t N I: E f i b i rvuAi Ls i : r.ifiii iflst JSil' r :-arrfLfl EidfeTifrl +t -i4r j1rci w ism 'iv- 'j'cnjn™ Cpc^rjling Flu*J* T*ehrti*0a TruSriRlfl ■Trjiniij \AiiniY. Paris IhTermadari i^ilrlirr flepplr Interm^tfsn ■f liuds plLT ta = j£ Sp&t ial TOdll ■Spaiiil juds Daiafcue E. IM Inter malic-n tVrifnu !i> E3 1 &MW Hunffl-r *KK5 Dp .-3 hiliunlkiit HSS tv BTA VlHSiWl DCS ■O • • fc 1 -" in; ■ Pi Qi i! »irln □ W.'I s '.: Tfrfjhf : . ■' Vt-riirnin Tpniciii.iv ■ ■. .“T - m k-*™ LF . 1 b IT frfc- nw PSi-fl f™ ui TIS DEDH Systems inform-stlon- i xn i k»t i i ^ i ^ i i ^ i £^1 i^i ji^i i J; ill* 1 rp»iv 1 i Iri -jiJ4. I.1I [ *** hi# ■'liiliaai nixtfic ntJT c» ijv !'! ’ 1 | yip EH Cw iJc1 (lean), the oxygen sensor signal voltage is approx. 4.3V If necessary, the ECM will “correct” the air/fuel ratio by regulating the ms injection time. The ECM monitors the length of time the sensors are operating in the lean, rich and rest conditions. The evaluation period of the sensors is over a predefined number of oscillation cycles and pump cell amperage. 38 Emissions Management Direct Oxygen Sensor Heating The oxygen sensor conductivity is efficient when it is hot (600° - 700° C). For this rea¬ son, the sensors contain heating elements. These “heated” sensors reduce warm up time, and retain the heat during low engine speed when the exhaust temperature is cool¬ er. OBD II requires monitoring of the oxygen sensor heating function and heating ele¬ ments for operation. The four oxygen sensor heating circuits receive operating voltage from the ECM Relay when KL15 is switched “ON”. Each of the sensors heaters are controlled through sepa¬ rate final stage transistors. The sensor heaters are controlled with a pulse width modulated voltage during a cold start. This allows the sensors to be brought up to operating temperature without the possibility of thermal shock. The duty cycle is then varied to maintain the heating of the sensors. When the engine is decelerating (closed throttle), the ECM increases the duty cycle of the heating elements to compensate for the decreased exhaust temperature. 39 Emissions Management Testing the Oxygen Sensor Testing should be performed using ISTA/IMIB Oscilloscope. List. The scope pattern should appear for a normal operating sensor. If the signal remains high (rich condition) the following should be checked: • Fuel Injectors • Fuel Pressure • Ignition System • Input Sensors that influence air/fuel mixture • Engine Mechanical If the signal remains low (lean condition) the following should be checked: • Air/Vacuum leak • Fuel Pressure • Input Sensor that influence air/fuel mixture • Engine Mechanical A MIXTURE RELATED FAULT CODE SHOULD BE INVESTIGATED | FIRST AND DOES NOT ALWAYS INDICATE A DEFECTIVE OXYGEN ^ SENSOR! 40 Emissions Management Catalytic Converter Monitoring The efficiency of catalyst operation is deter¬ mined by evaluating the oxygen consumption of the catalytic converters using the pre and post oxygen sensor signals. A properly operat¬ ing catalyst consumes most of the 02 (oxy¬ gen) that is present in the exhaust gas (input to catalyst). The gases that flow into the cata¬ lyst are converted from CO, HC and NOx to C02, H20 and N2 respectively. In order to determine if the catalysts are work¬ ing correctly, post catalyst oxygen sensors are installed to monitor exhaust gas content exiting the catalysts. The signal of the post cat. 02 sensor is evaluated over the course of several pre cat. 02 sensor oscillations. During the evaluation period, the signal of the post cat. sensor must remain within a rela¬ tively constant voltage range (700 - 800 mV). The post cat. 02 voltage remains high with a very slight fluctuation. This indicates a further lack of oxygen when compared to the pre cat. sensor. If this signal decreased in voltage and/or increased in fluctuation, a fault code will be set for Catalyst Efficiency and the “Malfunction Indicator Light” will illuminate when the OBD II criteria is achieved. Good Signal lli 3 a. 2 < O > PRE POST TIME 41 Emissions Management On-Board Refueling Vapor Recovery (ORVR) Index Explanation Index Explanation 1 Overpressure protection valve 9 Atmospheric vent line 2 Filling vent valve (rollover valve) 10 DM-TL (electrical control circuit) 3 Operating vent valve 11 ECM (DME) 4 Ventilation line 12 Evaporative emission (purge) control valve 5 Mushroom valve (“T” fitting) 13 Evaporative emission (purge) line 6 Carbon canister 14 Intake manifold 7 DM-TL (leakage diagnosis pump) 15 Engine air filter 8 Filter 16 M54 engine The ORVR system recovers and stores hydrocarbon fuel vapor that was previously released during refueling. Non ORVR vehicles vent fuel vapors from the tank venting line back to the filler neck and in many states reclaimed by a vacuum receiver on the filling station’s fuel pump nozzle. When refueling an ORVR equipped vehicle, the pressure of the fuel entering the tank forces the hydrocarbon vapors through the Filling Vent Valve (2) and the large tank venti¬ lation line (4) into the Carbon Canister (6). The HC is stored in the Carbon Canister and the system can then “breathe” through the DM-TL (7) and the filter (8). 42 Emissions Management The ventilation continues until the rising fuel level lifts the float in the Filling Vent Valve (2) and closes the outlet. When the ventilation outlet is closed, a pressure cushion (vapor area) is created in the fuel tank. This creates a backup of fuel into the filler neck and the tank is full. This leaves a vapor area of approximately 6 liters above the fuel level. This area provides integral liquid/vapor separation. The vapor condensates separate and drain back into the fuel. The remaining vapors exit the fuel tank (when sufficient pressure is present) through the Operating Vent Valve (3) to the Carbon Canister. A small diameter connection to the filler neck is provided by the Mushroom Valve “T fitting” (5). This is necessary for checking the filler cap/neck during Evaporative Leak Testing. The Operating Vent Valve is also equipped with a protection float in the event of an “overfill” situation. 43 Emissions Management On-Board Refueling Vapor Recovery (ORVR) E9x Vehicles Index Explanation Index Explanation 1 Electric Fuel Pump 13 Fuel Level Sensor 2 Feed Line 14 Refuelling Line Connection Piece 3 Check Valve 15 Refuelling Ventilation Line 4 Fuel Filter 16 Refuelling Ventilation 5 Feed Line to Engine 17 Left Operation Ventilation Valve 6 Fuel Injector 18 Right Operation Ventilation Valve 7 Pressure Regulator 19 Operation Ventilation Line 8 Check Valve 20 Diagnosis Module for Tank Leakage (DM-TL) 9 Left Suction Jet Pump 21 Atmosphere Line 10 Right Suction Jet Pump 22 Carbon Canister 11 Initial Filling Valve 23 Fuel Tank Vent Valve 12 Fuel Baffle 24 Digital Motor Electronics 44 Emissions Management The ORVR system recovers and stores hydrocarbon fuel vapors during refueling. When refueling the E90, a downward open adapter (14) is located on the refueling ventilation line (15) in the fuel tank. During the refueling procedure, the air can escape out of the tank via the refueling ventilation line (15) and the fuel filler neck. When the fuel level rises up to the opening of the refueling ventilation line, it is closed off and the fuel level increases in the fuel filler neck up to the fuel station pump. The fuel station pump then switches off automatically. After the fuel station pump has switched off, an expansion volume (approx. 10 liters) remains above the refueling ventilation line. Ventilation During Engine Operation The fuel vapors produced in the fuel tank pass: • through the operation ventilation valves (17 + 18) • through the ventilation line (19), • into the carbon canister AKF (20), • through the purge air line and • through the fuel tank vent valve TEV (22), • to the engine intake manifold. The two operation ventilation valves are located above the refueling ventilation adapter (14). They are connected by a line. The left operation ventilation valve (17) only has a ventilation function while the right operation ventilation valve (18) additionally has a pres¬ sure holding function (50 mbar). The aim of the pressure holding function is to avoid the remaining air of the expansion volume escaping via the carbon canister while refueling (with refueling ventilation line closed). 45 Emissions Management Evaporative Leakage Detection (DM-TL) This component ensures accurate fuel system leak detection for leaks as small as 0.5 mm by slightly pressurizing the fuel tank and evaporative compo¬ nents. The DM-TL pump contains an integral DC motor which is activated directly by the ECM. The ECM monitors the pump motor operating current as the measurement for detecting leaks. The pump also contains an ECM controlled change over valve that is energized closed during a Leak Diagnosis test. The change over valve is open during all other periods of operation allowing the fuel system to “breath” through the inlet filter. The DM-TL is located under the luggage compartment floor with the Carbon Canister. 1. In its inactive state, filtered fresh air enters the evaporative system through the sprung open valve of the DM-TL. 2. When the DME activates the DM-TL for leak testing, it first activates only the pump motor. This pumps air through a restrictor orifice (0.5 mm) which causes the electric motor to draw a specific amperage value. This value is equivalent to the size of the restrictor. 3. The solenoid valve is then energized which seals the evaporative system and directs the pump output to pressurize the evaporative system. • A large leak is detected in the evaporative system if the amperage value is not achieved. • A small leak is detected if the same reference amperage is achieved. • The system is sealed if the amperage value is higher than the reference amperage. AIR INLET 46 Emissions Management SSP-SP0000052267 Diagnostic module for fuel tank leakage fh-iX- Th#. miLUin hhil-rf! M z - l>0MI Wdk r To prevent condensation buildup in the DM-TL pump, a heating element is integrated into the housing of the pump. The heating element is ground controlled by the ECM. 47 Emissions Management Test Results The time duration varies between 30 & 360 seconds depending on the resulting leak diagnosis test results (developed tank pressure “amperage” within a specific time period). When the ECM detects a leak, a fault will be stored and the “Malfunction Indicator Light” will be illuminated. Depending on the amperage measurement detected by the ECM, the fault code dis¬ played will be “small leak” or “large leak”. Index Explanation Index Explanation A Current 2 Leak = 0.5mm B Overpressure 25hPa (25mbar) 3 No leak in system (leak <0.5mm) C Time 4 Reference measurement (leak 0.5mm) 1 Leak >1mm 5 Leakage measurement 48 Emissions Management Refuelling While a Leak Diagnosis is Taking Place: The ECM detects refueling during a leak diagnosis as a result of the pressure drop when the fuel filler cap is opened and the increase pressure while filling the tank is being filled. In this case, the leakage diagnosis is interrupted. The sole¬ noid valve in the DM-TL is switched off and the tank pres¬ sure escapes through the activated carbon canister. If refueling does not take place immediately after the fuel filler cap has been opened, the system will detect a large leak and the a fault will be stored in the ECM. If refueling is detected in the next driving cycle (increase in fuel level), the fault is cleared. The ECM detects refueling from a change in the fuel tank sending unit level. If the filler cap was not properly installed, when the leakage test is performed and leakage is detected; the variable indicator lamp (shown to the right) and the “Please Close Filler Cap” Check Control message will be displayed. If the filler cap is correctly installed and leakage is not present the next time the test is performed, the “Malfunction Indicator Light” will not be illuminated. Starting with 2002 MY, a heating element was added to the DM TL pump to elimi¬ nate condensation. The heater is provided battery voltage when KL_15 is switched “on” and the ECM pro¬ vides the ground path (see page 47). 49 Emissions Management Principle of Operation The Evaporative Leakage Detection is performed on the fuel storage system by the DM-TL pump which contains an integral DC motor that is activated by the ECM. The ECM monitors the pump motor operating current as the measurement for detecting leaks. The pump also contains an ECM controlled change over valve that is energized closed during a Leak Diagnosis test. The ECM initiates a leak diagnosis test every time the cri¬ teria are met. The criteria is as follows: • Engine OFF with ignition switched OFF. • ECM still in active state or what is known as “follow up mode” (ECM Relay ener¬ gized, ECM and components online for extended period after key off). • Prior to Engine/Ignition switch OFF condition, vehicle must have been driven for a minimum of 20 minutes. • Prior to minimum 20 minute drive, the vehicle must have been OFF for a minimum of 5 hours. • Fuel Tank Capacity must be between 15 and 85% (safe approximation between 1/4 - 3/4 of a tank). • Ambient Air Temperature between 4°C & 35°C (40°F & 95°F) • Altitude < 2500m (8,202 feet). • Battery Voltage - between 10.95 and 14.5 Volts PHASE 1 - Reference Measurement The ECM activates the pump motor. The pump pulls air from the filtered air inlet and passes it through a precise 0.5 mm reference orifice in the pump assembly. The ECM simul¬ taneously monitors the pump motor current flow. The motor current raises quickly and lev¬ els off (stabilizes) due to the orifice restriction. The ECM stores the stabilized amperage value in memory. The stored amperage value is the electrical equivalent of a 0.5 mm (0.020”) leak. i |C c£ u P < Tank C"han[j,*-45w EJoclrm ■Mwnr LDP u M FVte 1 frnsh Air 50 Emissions Management PHASE 2 - Leak Detection The ECM energizes the Change Over Valve allowing the pressurized air to enter the fuel system through the Charcoal Canister. The ECM monitors the current flow and com¬ pares it with the stored reference measurement over a duration of time. Once the test is concluded, the ECM stops the pump motor and immediately de-ener¬ gizes the change over valve. This allows the stored pressure to vent thorough the char¬ coal canister trapping hydrocarbon vapor and venting air to atmosphere through the fil¬ ter. 51 Emissions Management Evaporative Emission Purging Evaporative Emission Purging is regulated by the ECM controlling the Evaporative Emission Valve. The Evaporative Emission Valve is a solenoid that regu¬ lates purge flow from the Active Carbon Canister into the intake manifold. The ECM Relay provides operat¬ ing voltage, and the ECM controls the valve by regu¬ lating the ground circuit. The valve is powered open and closed by an internal spring. The “purging” process takes place when: • Oxygen Sensor Control is active • Engine Coolant Temperature is > 67° C • Engine Load is present The Evaporative Emission Valve is opened in stages to moderate the purging. • Stage 1 opens the valve for 10 ms (milli-seconds) and then closes for 150 ms. • The stages continue with increasing opening times (up to 16 stages) until the valve is completely open. • The valve now starts to close in 16 stages in reverse order • This staged process takes 6 minutes to complete. The function is inactive for 1 minute then starts the process all over again. • During the purging process the valve is completely opened during full throttle opera¬ tion and is completely closed during deceleration fuel cutoff. Evaporative Purge System Flow Check is performed by the ECM when the oxygen sensor control and purging is active. When the Evaporative Emission Valve is open the ECM detects a rich/lean shift as monitored by the oxygen sensors indicating the valve is functioning properly. If the ECM does not detect a rich/lean shift, a second step is performed when the vehi¬ cle is stationary and the engine is at idle speed. The ECM opens and close the valve (abruptly) several times and monitors the engine rpm for changes. If there are no changes, a fault code will be set. OPERATING POWER FROM ECM MAIN RELAY VAPORS FROM CHARCOAL CANISTER VAPORS TO VACUUM PORT ON THROTTLE HOUSING 52 Emissions Management Carbon Canister As the hydrocarbon vapors enter the canister, they will be absorbed by the active carbon. The remaining air will be vented to the atmosphere through the end of the canister, DM TL and filter, allowing the fuel tank to “breath”. When the engine is running, the canister is "purged" using intake manifold vacuum to draw air through the canister which extracts the HC vapors into the combustion cham¬ ber. The Carbon Canister with DM TL and air filter are located at the right rear underside of the vehicle, below the luggage compartment floor. Evaporative Emission Valve This ECM controlled solenoid valve regulates the purge flow from the Carbon Canister into the intake manifold. The ECM Relay provides operating voltage, and the ECM controls the valve by regulating the ground circuit. The valve is powered open and closed by an inter¬ nal spring. If the Evaporative Emission Valve circuit is defective, a fault code will be set and the “Malfunction Indicator Light” will illuminate when the OBD II criteria is achieved. If the valve is “mechanically” defective, a drive- ability complaint could be encountered and a mixture related fault code will be set. OPERATING POWER FROM ECM MAIN RELAY VAPORS FROM CHARCOAL CANISTER Jr VAPORS TO VACUUM PORT ON THROTTLE HOUSING 53 Emissions Management Secondary Air Injection This system is required to reduce HC and CO emissions while the engine is warming up. Immediately following a cold engine start (-10 to 60°C) fresh air/oxygen is injected directly into the exhaust stream. The temperature signal is provided to the ECM by the Air Temperature Sensor in the HFM. The ECM provides a ground circuit to activate the Secondary Air Injection Pump Relay. The relay supplies voltage to the Secon-dary Air Injection Pump. The single speed pump runs for approximately 90 seconds after engine start up. Below -10° Cl the pump is activated briefly to “blow out” ( { \ any accumulated moisture. SSP-SP0000017943 Secondary air pump Secondapy &'t (m % v 54 Emissions Management Secondary Air Injection Monitoring The monitoring of Secondary Air is performed by the ECM via the use of the pre-catalyst oxygen sensors. Once the air pump is active and is air injected into the exhaust system the oxygen sensor signals will indicate a lean con¬ dition (up to 16 seconds). If the oxygen sensor signals do not change within a predefined time a fault will be set and identify the faulty bank. If the additional oxygen is not detected for two consecutive cold starts, the ECM determines a general fault with the function of the secondary air injection system. After completing the next cold start and a fault is again present the "Malfunction Indicator Light” will be illuminated when the OBDII criteria is achieved. Secondary Air System As on N73 engine, the N74 is equipped with a secondary air system. Blowing additional air (secondary air) into the exhaust gas duct in the cylinder head during the warm-up phase initiates thermal post-combustion that leads to a reduction in the unburned hydro¬ carbons (HC) and carbon monoxide (CO) contained in the exhaust gas. The energy gen¬ erated here heats up the catalytic converter faster in the warm-up phase and increases its conversion rate. The catalytic converter response temperature (light-off temperature) of 300°C is reached only a few seconds after the engine is started. What is new is that there is one pressure sensor before each secondary air valve. The function of the secondary air system is monitored by registering the pressure conditions. Secondary air pump The electrically operated secondary air pump is attached to the cylinder head of cylinder bank 1. During the warm-up phase, the pump draws in fresh air from the engine compartment. This is cleaned by the filter integrated in the pump and delivered across the pressure line to the two sec¬ ondary air valves. After the engine start, the secondary air pump is supplied with vehicle voltage by the DME via the secondary air pump relay. The switched-on period is about 20 seconds and it depends essentially on the coolant temperature at engine start. It is activated from a coolant temperature of +5°C to +50°C (40°F to 120°F). 55 Emissions Management Secondary air valve A secondary air valve is bolted onto the rear of each cylinder head. The secondary air valve opens as soon as the system pressure generated by the secondary air pump exceeds the opening pressure of the valve. Secondary air is fed via the secondary air line into the elongated passage of the cylinder head. From the elongated passage, 24 tap holes lead to the 12 exhaust ducts where the thermal post-combustion takes place. The secondary air valve closes as soon as the secondary air pump switches off, thus preventing exhaust gas from flowing back to the secondary air pump. Secondary Air Valve and Pressure Sensor On-board diagnosis of secondary air system Monitoring takes place with the help of the pressure sensors that are fitted before each of the secondary air valves. The exhaust gas oxygen sensors are also used. The overall diagnosis is divided into a rough diagnosis that begins immediately after the secondary air pump starts up and the fine diagnosis that begins around 12 to 14 sec¬ onds after the secondary air injection starts. The rough diagnosis uses only the pressure signals. Every fault in the secondary air sys¬ tem is detected if there is a drop below a minimum pressure in the event of a leakage or if a maximum pressure is exceeded when a valve is clogged or jammed closed. However, under certain circumstances, it might not be possible to assign the fault correctly, because the pressure sensors indicate the same pressure due to the connecting line. The fine diagnosis uses the exhaust gas oxygen sensor signals in addition to the pres¬ sure signals. The combination of exceeding or falling short of fault thresholds for the pressure and exhaust gas oxygen sensor values means the fault can be precisely assigned to the relevant cylinder bank. The fine diagnosis relies on the oxygen sensor readiness, this is available much later than in naturally aspirated engines due to the heat loss through theturbocharger. There is also an electrical diagnosis for the secondary air pump relay and for the pres¬ sure sensors. These indicate the usual electrical faults (line disconnection, short circuit to ground, short circuit to supply voltage). There is an additional mutual plausibility check of the pressure sensors on initialization with ambient pressure. 56 Emissions Management Misfire Detection Misfire detection is part of the OBD II regulations the ECM must determine misfire and also identify the specific cylinder(s). The ECM must also determine the severity of the misfire and whether it is emissions relevant or catalyst damaging based on moni¬ toring crankshaft acceleration. Emission Increase • Within an interval of 1000 crankshaft revolutions, the ECM adds the detected misfire events for each cylinder. If the sum of all cylinder misfire incidents exceeds the pre¬ deter- mined value, a fault code will be stored and the “Malfunction Indicator Light” will be illuminated. • If more than one cylinder is misfiring, all misfiring cylinders will be specified and the individual fault codes for each misfiring cylinder, or multiple cylinders will be stored. The “Malfunction Indicator Light” will be illuminated. Catalyst Damage • Within an interval of 200 crankshaft revolutions the detected number of misfiring events is calcu¬ lated for each cylinder. The ECM monitors this based on load/rpm. If the sum of cylinder misfire incidents exceeds a predetermined value, a “Catalyst Damaging” fault code is stored and the “Malfunction Indicator Light” will be illuminated. If the cylinder misfire count exceeds the predeter¬ mined threshold the ECM will take the following mea¬ sures: The oxygen sensor control will be switched to open loop. The cylinder selective fault code is stored. If more than one cylinder is misfiring the fault code for all individual cylinders and for multiple cylinders will be stored. The fuel injector to the respective cylinder(s) is deactivated. 57 Emissions Management Ambient Barometric Pressure The Integrated Ambient Barometric Pressure Sensor is part of the ECM and is not ser¬ viceable. The internal sensor is supplied with 5 volts. In return it provides a linear voltage of approx. 2.4 to 4.5 volts representative of barometric pressure (altitude). The ECM monitors barometric pressure for the following reasons: • The barometric pressure signal along with calculated air mass provides an additional correction factor to further refine injection “on” time. • Provides a base value to calculate the air mass being injected into the exhaust sys¬ tem by the Secondary Air Injection System. This correction factor alters the sec¬ ondary air injection “on” time, optimizing the necessary air flow into the exhaust system. f\ INTEGRAL BAROMETRIC PRESSURE SENSOR PROVIDES ADDITIONAL CORRECTION FACTOR FOR FOLLOWING FUNCTIONS 58 Emissions Management Crankcase Ventilation One of the major changes on the new NG6 engines is that the crankcase ventilation sys¬ tem has been upgraded and improved. This applies to all of the new NG6 versions (N52KP, N51 and N54). There are two distinct versions of crankcase ventilation. One type is unique to the N54 and the other applies to N51 and N52KP. The N52, which is still in production continues to use the “external” crankcase ventilation system with the electrically heated crankcase ventilation valve/cyclone separator. Crankcase Ventilation System on N52 59 Emissions Management Crankcase Ventilation (N51 and N52KP) The crankcase ventilation system on the N51 and N52KP has been modified as com¬ pared to the N52. The system is integrated into the plastic cylinder head cover. The crankcase gases are regulated by a crankcase ventilation valve similar to the design used on the N62. The crankcase vent valve is currently part of the cylinder head cover and is not replaceable as a separate component. Oil separation is carried out via a “labyrinth” system and two cyclone separators which are incorporated into the cylinder head cover. By having the system components inte¬ grated into the cylinder head cover, the crankcase gases are heated by the engine rather than an electric heater as on the N52. However, there is still one electric heating ele¬ ment at the manifold inlet. Once the liquid oil is separated from the crankcase vapors, the oil is allowed to drain back through check valves back into the engine. N52KP Cylinder Head Cover (cutaway view) Integrated cyclone separator Oil drainback valve Crankcase vent valve 60 Emissions Management Crankcase Ventilation (N54) Since the N54 is a turbocharged engine, the crankcase ventilation system has to meet certain design requirements. For example, when the engine is in turbocharged mode, the increased manifold pressure should not have an adverse effect on the crankcase venting. This is why, there is no crankcase ventila¬ tion valve in the system. The system consists of four small cyclone separators which are inte¬ grated into the plastic cylinder head cover. The flow of crankcase gases is metered through a series of restrictions which control the ulti¬ mate crankcase pressure. One of the main operating principles behind the crankcase venting system on the N54 is that there are two strategies - one for the turbocharged mode and one for “non-tur- bocharged” operation such as decel. These strategies are dependent upon the intake manifold pressure. N54 Cylinder Head Cover (cutaway view) cyclone separator 61 Emissions Management 62 Emissions Management Crankcase Ventilation System Overview (N55) The blow-by gasses flow into the settling chamber of the cylinder head cover through an opening located in the rear of the cover. Here, the blow-by gasses are directed through holes on to an impact plate, against which the oil impacts at high speed, and drains off. The blow-by gasses, cleaned of oil, flow via the pressure control valve (depending on the operating mode) through the non-return valves into the inlet pipe upstream of the turbocharger, or via passages in the cylinder head ahead of the intake valves. The sepa¬ rated oil is drained via a return flow duct into the oil pan. Naturally Aspirated Mode (N55) The standard function can only be used as long as a vacuum prevails in the intake air manifold, i.e. in naturally-aspirated engine mode. With the engine operating in naturally-aspirated mode, the vacuum in the intake air mani¬ fold opens the non-return valve (15) in the blow-by duct within the cylinder head cover. This draws off blow-by gasses via the pressure control valve. At the same time, the vac¬ uum also closes the second non-return valve (12) in the duct to the charge air intake pipe. The blow-by gasses flow via a distribution rail integrated in the cylinder head cover, through the intake passages (16) in the cylinder head, which lead directly into the intake ports, ahead of the valves. Boost Mode (N55) As the pressure in the intake air manifold increases in boost mode, blow-by gasses can no longer be introduced via the passages in the cylinder head, otherwise, the boost pres¬ sure could enter the crankcase. A non-return valve (15) in the blow-by channel within the cylinder head cover closes the connection (16) to the intake air manifold. This protects the crankcase from excess pressure. The increased demand for fresh air creates a vacuum in the clean air pipe between the turbocharger and intake silencer. This vacuum is sufficient to open the non-return valve (12) and draw the blow-by gasses via the pressure control valve. 63 Emissions Management Crankcase Ventilation Overview (N55) Crankcase ventilation system in “decel mode” 64 Emissions Management Index Explanation A Ambient pressure B Vacuum C Exhaust gas D Oil E Blow-by gas 1 Air cleaner 2 Intake manifold 3 Impact plates 4 Oil return channel 5 Crankcase 6 Oil sump 7 Oil return channel 8 Exhaust turbocharger 9 Oil drain valve 10 Charge air intake line 11 Hose to charge air intake line 12 Non-return valve 13 Pressure regulating valve 14 Throttle valve 15 Non-return valve 16 Passages in cylinder head and cylinder head cover 65 Emissions Management Crankcase Ventilation System Overview (N55) Crankcase ventilation system in turbocharged mode (boost mode) 66 Emissions Management If a customer complains about high oil consumption and oil is discovered in the turbocharger, it should not be immediately assumed that the turbocharger is defective. If the oil is present in the fresh air pipe (before the turbocharger) then the entire engine should be checked. Index Explanation A Excess pressure B Vacuum C Exhaust gas D Oil E Blow-by gas 1 Air cleaner 2 Intake manifold 3 Impact plates 4 Oil return channel 5 Crankcase 6 Oil sump 7 Oil return channel 8 Exhaust turbocharger 9 Oil drain valve 10 Charge air intake line 11 Hose to charge air intake line 12 Non-return valve 13 Pressure regulating valve 14 Throttle valve 15 Non-return valve 16 Passages in cylinder head and cylinder head cover 67 Emissions Management 68 Emissions Management Crankcase Ventilation System Overview (N54) Naturally Aspirated Mode (N54) When the engine has low manifold pressure such as in decel, the crankcase vapors are routed through a channel (15) between the cylinder head cover and intake manifold. The liquid oil is separated before the channel in the cyclonic separators (3) in the cylinder head cover. The liquid oil returns to the engine via the oil discharge valve (4). The channel contains a pressure restrictor (16) which regulates the flow of crankcase vapors. During deceleration, the crankcase vapors (E) are directed via a check valve (14) which is located in the cylinder head cover. The check valve is opened when low pressure is present in the intake manifold (throttle closed). Also, a PTC heater has been integrated into the intake manifold inlet. The inlet pipe is connected to the channel (15) and prevent any moisture from freezing at the inlet. Boost Mode (N54) When in turbocharged mode, the pressure in the intake manifold increases and then closes the check valve (14). Now, a low pressure is present in the charge air suction line (10). This causes a low pressure in the hose (11) leading to the manifold check valve (12). The crankcase vapors (after separation) are directed through the check valve (12) into the charge air suction line (10) and ultimately back into the engine. The check valve (12) also prevent boost pressure from entering the crankcase when the intake manifold pressure is high. 69 Emissions Management Crankcase Ventilation System Overview (N54) Crankcase ventilation system 70 Emissions Management Index Explanation Index Explanation A Overpressure 7 Oil sump B Low Pressure (Vacuum) 8 Oil return channel C Exhaust gas 9 Turbocharger D Liquid oil 10 Charge air suction line, bank 2 E Blow-by gases (Crankcase vapors) 11 Hose to charge air suction line, bank 2 1 Air cleaner 12 Check valve, manifold 2 Intake manifold 13 Throttle valve 3 Cyclone separators 14 Check valve, charge air suction line 4 Oil discharge valve 15 Channel to intake manifold 5 Venting channel 16 Pressure restrictor 6 Crankshaft cavity 71 Emissions Management Crankcase Ventilation System Overview (N54) Crankcase ventilation system in “turbocharged mode” Early Production: i External Passage ! Late Production: j Internal Passage 1 If a customer complains about high oil consumption and oil is discovered in the turbocharger, it should not be immediately assumed that the turbocharger is defective. If the oil is present in the fresh air pipe (before the turbocharger) then the entire engine should be checked. 72 Emissions Management Index Explanation Index Explanation A Overpressure 7 Oil sump B Low Pressure (Vacuum) 8 Oil return channel C Exhaust gas 9 Turbocharger D Liquid oil 10 Charge air suction line, bank 2 E Blow-by gases (Crankcase vapors) 11 Hose to charge air suction line, bank 2 1 Air cleaner 12 Check valve, manifold 2 Intake manifold 13 Throttle valve 3 Cyclone separators 14 Check valve, charge air suction line 4 Oil discharge valve 15 Channel to intake manifold 5 Venting channel 16 Pressure restrictor 6 Crankshaft cavity Be aware that any check valve failure could cause excessive oil con¬ sumption possibly accompanied by blue smoke from the exhaust. This should not be mistaken for a failed turbocharger. Always perform a complete diagnosis of the crankcase ventilation system, before replacing any turbocharger or associated components. 73 Emissions Management Crankcase Ventilation Heating Also integrated into the design of the crankcase ventilation is an electric heating system designed to prevent moisture buildup. Moisture buildup can eventually lead to ice at low ambient temperatures leading to malfunctions of the crankcase ventilation. The crankcase vent valve and cyclonic separator are also insulated by a protective foam covering to provide additional shelter from low ambient temperatures. The PTC heating elements are integrated into the crankcase ventilation valve and hose assemblies. There is a junction point on the intake manifold which provides a connec¬ tion point for the individual heating elements. There is also a heating element located on the centrally located port on the intake mani¬ fold. This port is also provided with a separate heating circuit controlled by a PTC thermistor. The ECM receives the ambient temperature information from the outside temperature sensor. SSP-SP0000052251 Oil Supply (Engine Breather Heater) 1 1 ■' J ■ I '.vj ‘-vt- - Si 74 Emissions Management