Diagnostic Trouble Codes - with Charts MINI Cooper S I

INTRODUCTION

OBD-II Diagnostic Trouble Codes (DTCs) are accessed using a generic scan tool connected to vehicle Data Link Connector (DLC). (Scheme 1) MINI trouble codes can be accessed using BMW's GROUP TESTER ONE (GT-1) or DISplus hardware system. These are often referred to as BMW SCAN TOOL.

The OBD-II connector is located in driver's footwell to left of steering column. (Scheme 2)

Control unit provides a substitute value if a failure occurs in an engine performance related component, such as engine (coolant) temperature sensor, intake air temperature sensor, airflow meter or exhaust gas oxygen sensor. These substitute values are canceled when normal engine operation is resumed.

Note. All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated otherwise in testing procedures.

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MALFUNCTION INDICATOR LIGHT

The Malfunction Indicator Light (MIL) will illuminate under the following conditions

1. Upon the completion of the next consecutive driving cycle where the previously faulted system is monitored again and the emissions relevant fault is again present.
2. Immediately if a catalyst damaging fault occurs.

The illumination of the light is performed in accordance with the Federal Test Procedure (FTP) which requires the light to go on when

1. 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 FTP.
2. Manufacturer-defined specifications are exceeded.
3. An implausible input signal is generated.
4. Catalyst deterioration causes HC-emissions to exceed a limit equivalent to 1.5 times the standard (FTP).
5. Misfire faults occur.
6. A leak is detected in the evaporative system, or purging is defective.
7. PCM fails to enter closed-loop oxygen sensor control operation within a specified time interval.
8. Engine control or automatic transmission control enters a limp home operating mode.
9. Ignition is in on position before cranking = bulb check function.

A fault code is stored within the PCM upon the first occurrence of a fault in the system being checked. The Malfunction Indicator Light (MIL) 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. If the second drive cycle was not complete and the specific function was not checked, PCM counts third drive cycle as "next consecutive" drive cycle. MIL is illuminated if the function is checked and the fault is still present. (Scheme 4)

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If there is an intermittent fault present and does not cause a fault to be set through multiple drive cycles, 2 complete consecutive drive cycles with the fault present are required for MIL to be illuminated. Once MIL is illuminated it will remain illuminated unless the specific function has been checked without fault through 3 complete consecutive drive cycles. Fault code will also be cleared from memory automatically if specific function is checked through 40 consecutive drive cycles without the fault being detected or with the use of either DISplus, GT-1 or scan tool. In order to clear a catalyst damaging fault from memory, the condition must be evaluated for 80 consecutive cycles without the fault reoccurring.

CHECK FILLER CAP INDICATOR LIGHT

After refueling and turning ignition on, PCM detects a fuel level increase. When the ignition is turned off, PCM activates a brief test to check filler cap. If filler cap was not properly installed and vehicle is started and driven at a speed greater than 6 MPH (10 Km/h), the CHECK FILLER CAP light on instrument panel will illuminate for 25 seconds, then go out. The second time the ignition is cycled off, PCM is activated to test filler cap. If loose, when vehicle is started and driven at a speed greater than 6 MPH (10 Km/h), CHECK FILLER CAP light will be illuminated for 25 seconds, then go out. If filler cap is properly secured, Malfunction Indicator Light (MIL) will not be illuminated and a fault code will not be stored in PCM. The third time ignition is cycled off, PCM is activated to test filler cap. If loose, a LARGE LEAK fault code is stored in PCM. MIL will be illuminated the next time engine is started. Variable indicator light and PLEASE CLOSE FILLER CAP check control message will be displayed.

Emission Reduction Stages

While OBD-II has the function of monitoring for emission related faults and alerting the operator of the vehicle, the National Low Emission Vehicle Program requires a certain number of vehicles produced (specific to manufacturing totals) currently comply with the following emission stages

1. TLEV: Transitional Low Emission Vehicle
2. LEV: Low Emission Vehicle
3. ULEV: Ultra Low Emission Vehicle

MINI DIAGNOSTIC HARDWARE

Note. MINI utilizes 2 main types of diagnostic hardware: the Diagnostic Information System Plus (DISplus) and the Group Tester One (GT-1). See ON-BOARD DIAGNOSTICS . These are often referred to as BMW SCAN TOOLS.

DIS Plus

DIS Plus diagnostic system features a comprehensive multimeter system (including an oscilloscope) that is used to perform various tests and measurement during the diagnosis and troubleshooting procedures. DIS also includes the Technical Information System (TIS). TIS is the same system that operates through dealer main computer system.

Group Tester One (GT-1)

GT-1 replaces the MoDiC series of portable diagnostic tools. It has the same processor as the DISplus. Other features include a DVD ROM drive, TFT color display, integrated PCMCIA card reader, integrated chip card reader, touch screen (same as DISplus), workshop grade case, ASM-technology motherboard, temperature operating range from 35°F to 105°F, 2.5 hours of operation with a fully charged battery, and can be powered by vehicle battery.

A diagnostic cable is used to connect diagnostic head to a vehicle with the 20 pin underhood connector. Cable consists of 20 pin connector, cable and 21-pin plug for connection to the head. An OBD-II diagnostic cable is used to connect diagnostic head to OBD-II diagnostic connector.

Hard & Intermittent Failures

A fault code is stored within the respective control module upon first occurrence of a fault in system being checked. CHECK ENGINE light will not be illuminated until completion of second consecutive driving cycle where previously faulted system is again monitored and a fault is still present or a catalyst damaging fault has occurred. If second drive cycle was not complete and specific function was not checked, PCM counts third drive cycle as next consecutive drive cycle. CHECK ENGINE light is illuminated if function is checked and fault is still present.

If an intermittent fault is present, and it does not cause a fault to be set through multiple drive cycles, 2 complete consecutive drive cycles with fault present are required for CHECK ENGINE light to be illuminated. Once CHECK ENGINE light is illuminated it will remain on unless specific function has been checked without fault through 3 complete consecutive drive cycles.

Fault code will also be cleared from memory automatically if specific function is checked through 40 consecutive drive cycles without fault being detected or with use of DIS Plus or GT-1 scan tool. To clear a catalyst damaging fault from memory, condition under which fault occurred must be evaluated for 80 consecutive cycles without fault reoccurring.

OBD-II Diagnostics

Malfunction Indicator Light (MIL) can be diagnosed with an aftermarket scan tool that allows technicians without MINI special tools or equipment to diagnose an emission system failure. With the use of a universal scan tool connected to Data Link Connector (DLC), an SAE standardized DTC can be obtained, along with condition associated with the illumination of MIL. Using DISplus or GT-1, a fault code and the conditions associated with its setting can be obtained prior to the illumination of the MIL.

OBD-II Diagnostic Trouble Codes (DTC) are designed to be identified by their alpha/numeric structure. DTCs start with letter "P" for powertrain related systems. (Scheme 5) DTCs are stored whenever the Check Engine Light (MIL) is illuminated. Universal diagnostic access to DTCs is via a standardized Diagnostic Link Connector (DLC) using a standardized tester (scan tool). DTCs only provide one set of environmental operating conditions when a fault is stored. This single freeze frame refers to vehicles environmental conditions for a specific time when fault first occurred. Information which is stored is limited in scope. This information may not even be specific to type of fault. On MINI, OBD-II monitors following systems

1. CATALYST MONITORING.
2. MISFIRE MONITORING.
3. EVAPORATIVE SYSTEM MONITORING.
4. FUEL SYSTEM MONITORING.
5. OXYGEN SENSOR MONITORING.
6. THERMOSTAT MONITORING.
7. PLAUSIBILITY DIAGNOSIS.
8. COHERENCE DIAGNOSIS.

Scheme 4

MINI Diagnostics

MINI diagnostic trouble codes are stored as soon they occur even before the Check Engine Light (MIL) comes on. MINI codes are defined to provide greater detail to fault specific information.

MINI codes are capable of recording current fault status. Code will advise whether fault is actually still present, not currently present or intermittent. Fault specific information is stored and accessible through DIS Plus or GT-1. MINI codes determine diagnostic output for BMW DIS Plus or GT-1.

OBD II Drive Cycles & Trips

A "Drive cycle" consists of engine startup and engine shutoff. "Trip" is defined as vehicle operation (following an engine-off period) of duration and driving style so that all components and systems are monitored at least once by the diagnostic system except catalyst efficiency or evaporative system monitoring. This definition is subject to the limitations that the manufacturer-defined trip monitoring conditions are all monitored at least once during the first engine start portion of the Federal Test Procedure (FTP). Within this text the term "customer driving cycle" will be used and is defined as engine start-up, operation of vehicle (dependent upon customer drive style) and engine shut-off.

Federal Test Procedure (FTP) is a specific driving cycle that is utilized by the EPA to test light duty vehicle emissions. As part of the procedure for a vehicle manufacturer to obtain emission certification for a particular model/engine family the manufacturer must demonstrate that the vehicle(s) can pass the FTP defined driving cycle two consecutive times while monitoring various components/systems. Some of the components/systems must be monitored either once per driving cycle or continuously. Systems and their components required to be monitored once within one driving cycle: Oxygen Sensors, Catalyst Efficiency and Evaporative Vapor Recovery System.

Due to the complexity involved in meeting the test criteria within the FTP defined driving cycle, all tests may not be completed within one "customer driving cycle". The test can be successfully completed within the FTP defined criteria, however customer driving styles may differ and therefore may not always monitor all involved components/systems in one "trip".

Components/systems required to be monitored continuously: Cylinder Misfire Detection, Fuel system, Oxygen Sensors and all emissions related components/systems - EMS or EML (comprehensive component monitoring). The graph shown below is an example of the driving cycle that is used by BMW to complete the FTP.

Scheme 5

The diagnostic routine shown above will be discontinued whenever: Engine speed exceeds 3000 RPM, Large fluctuations in throttle angle, Road speed exceeds 60 MPH. Driving criteria shown can be completed within the FTP required - 11 miles in a controlled environment such as a dyno test or test track. A "customer driving cycle" may vary according to traffic patterns, route selection and distance traveled, which may not allow the "diagnostic trip" to be fully completed each time the vehicle is operated.

Readiness Flags

Readiness Flags provide status of required emissions system monitoring. The systems available for readiness flag status are: Misfiring Stage A (Catalyst Damaging Misfire), Misfiring Stage B1 (Sum of the Emission Increasing Misfires in the first 1000 Revs), Misfiring Stage B4 (Sum of the Emission Increasing Misfires 1000 Revs), EVAP 1, EVAP 2, EVAP 3, EVAP 4, Catalytic converter, Oxygen Sensor Control, Oxygen Sensor 1 (Pre-Cat) and Oxygen Sensor 2 (Post-Cat).

Complete System Test Results are indicated by Test Completed or Not Completed. A "Readiness Code" must be stored after any clearing of fault memory or disconnection of the EMS2000. A readiness code of "0" will be stored after a complete diagnostic 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.

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. 1 = EGR Monitoring (=0, N/A with MINI), 0 = Oxygen Sensor Heater Monitoring, 1 = Oxygen Sensor Monitoring, 1 = Air Conditioning (=0, N/A with MINI), 0 = Secondary Air Delivery Monitoring (N/A with MINI), 1 = Evaporative System Monitoring, 1= Catalyst Heating (=0, N/A with MINI at this time), and 0 = Catalyst Efficiency Monitoring. Drive the car in such a manner that all tests listed above can be completed (refer to the FTP cycle). When the complete "readiness code" equals "0" then all tests have been completed and the system has established its "readiness".

RETRIEVING & ERASING DIAGNOSTIC TROUBLE CODES

OBD-II Diagnostic Trouble Codes (DTC) can be retrieved or erased using generic scan tool connected to Data Link Connector (DLC). Follow scan tool manufacturer's instructions. MINI fault codes can be retrieved or erased using Diagnostic Information System Plus (DISplus) or Group Tester One (GT-1). BMW diagnostic hardware directs user to a specific test routine which provides diagnostic information only available to those who have the BMW hardware.

DIAGNOSTIC TROUBLE CODE CROSS-REFERENCE & TABLES

MINI Diagnostic Trouble Codes (DTCs) are separated by fuel system type, engine, and date of manufacture. See DIAGNOSTIC TROUBLE CODE CROSS-REFERENCE table to determine which specific table applies to a particular fuel system type, engine, and model year. Model specific tables contain OBD-II (PCode) and MINI-specific (MINI-FC) DTCs. DTCs in model-specific tables link to appropriate diagnosis, if available.

Note. Diagnosis is not available for all DTCs.

DIAGNOSTIC TROUBLE CODE CROSS-REFERENCE

TABLE "A" COOPER W10 ENGINE: 2BMXV01.6R50

TABLE "B" ECU: COOPER W10 ENGINE: 3BMXV01.6R50 & 3BMXV01.6R5R

TABLE "C" ECU: COOPER W10 ENGINE: 4BMXV01.6R50

TABLE "D" ECU: COOPER S W11 ENGINE: 2BMXV01.6R50

TABLE "E" ECU: COOPER S W11 ENGINE: 3BMXV01.6R50 & 3BMXV01.6R5R

TABLE "F" ECU: COOPER S W11 ENGINE: 4BMXV01.6R50

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TEST GROUP IDENTIFICATION

MINI supplies test group information in 9 categories. Specific engine family test group identification number (for example: 4BMXV01.6R50) can be found on emission label in engine compartment.

1. «CATALYST MONITORING»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts)
2. «MISFIRE MONITORING»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts)
3. «EVAPORATIVE SYSTEM MONITORING»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts)
4. «FUEL SYSTEM MONITORING»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts)
5. «OXYGEN SENSOR MONITORING»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts)
6. «THERMOSTAT MONITORING»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts)
7. «PLAUSIBILITY DIAGNOSIS»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts__plausibility-diagnosis)
8. «COHERENCE DIAGNOSIS»(/mini/cooper-s/i-2000-2006/remont/testing-diagnostics/#diagnostic-trouble-codes-with-charts__coherence-diagnosis)

General Description

1. This solution was chosen to fulfill OBD's requirement which is based on Oxygen Storage Capacity (OSC). During a controlled stimuli (special A/F pulses in engine steady state conditions), the downstream O2 sensor signal is analyzed to evaluate the OSC of the catalyst. The OSC is correlated experimentally with the global HC efficiency and HC emission during cycle. It represents the quantity of oxygen that is really used for the oxidation-reduction reaction by the catalytic converter (stored in lean excursion and consumed in the rich excursion).
2. Description Of Open Loop Diagnosis - Catalyst monitoring is a sequential diagnosis made on steady state conditions and this monitoring is intrusive. Three phases are composing the diagnosis: Engine stabilization. Controlled stimuli - stabilization. Controlled stimuli - diagnosis.
3. If a problem has occurred with the downstream sensor during the catalyst diagnosis, a sensor diagnosis is done. During the "Controlled Stimuli - Diagnosis Phase" the downstream sensor activity is measured and corresponds to the OSC of the catalyst. If this activity is high (low OSC) the diagnosis criteria DOWN_DYN_CAT is high.
4. If one of the monitoring conditions is not met or if the mass air flow deviates too much from the value stored at the start of this test phase, the test is interrupted and the system returns to the out of diagnosis state.
5. Downstream sensor diagnosis phase: If throughout the Controlled Stimuli phase, repeated several times, the downstream sensor has not moved, the A/F closed loop mode is delayed in order to test the sensor. If the downstream sensor sends a signal indicating a rich (lean) mixture), the injection time is forced to lean (rich) until the sensor switches over or until the end of a delay. If this delay expires, the sensor is treated as failed. The following reasons may apply: A leak in the exhaust line. A damaged sensor.
6. Electrical failure (short circuit and open circuit of signal and heater are treated as comprehensive components. If the catalyst diagnosis has been done without any problem, the downstream sensor is treated as good and a sensor diagnosis is not required.
7. If monitoring conditions for the diagnosis are fulfilled, the system informs the OBD sequencer and waits for its authorization to start catalyst diagnosis. The OBD sequencer manages the priorities in case of multiple diagnosis requests (catalyst diagnosis and O2 sensor diagnosis).

Measuring Principle, Segment Period Acquisition

1. The acquisition of the segment period is performed through an angular range of 180 degree crank angle. NC_CYL_NR is the number of cylinder. The segment starts NC_MIS_PHA CA before TDC. To compute an engine roughness value for a 4 cylinder engine, n = 9 contiguous valid segments are required.
2. Physical Background - Misfire induces a decrease of the engine speed, therefore a variation in the segment period. The misfire detection is based on the observation of this variation of segment period. Main causes of misfiring: injector shut-off, fuel pressure problems, fuel combustion problems and ignition cut-off.
3. Limits For Strategy Application - Variation in the engine torque caused by phenomenon other than misfiring must be recognized in order to inhibit misfiring monitoring. For example: Negative torque. Trailing throttle/acceleration transition. Ignition retardation without change limitation. Air conditioning compressor activation. Rough road detection Cylinder shut-off (engine speed limitation or vehicle speed limitation). Crankshaft oscillation.

The monitoring uses a Leak Detection Pump (LDP). The LDP is an electrically/vacuum actuated device that will pressurize the evaporative emission system for the purpose of detecting leaks and verifying canister purge valve.

Leak Detection

The leak detection is performed by means of 2 main phases

1. Tank system over-pressurizing.
2. Leak magnitude measurement.

During leak detection, canister purge valve and canister vent valve (CVV) are closed.

The Engine Control Module (ECU) causes the pump diaphragm to cycle at fixed frequency and for a fixed stroke number. During the pumping, air is drawn from outside into the fuel tank system, and system pressure increases.

Once the tank system over-pressure phase is finished, the leak measurement phase starts. The diaphragm stroke is limited by the top of the diaphragm chamber and a position defined by a reed switch level. The over-pressure slows the diaphragm movement. The pump cycle duration depends on the tank pressure. So the evolution of this time shows the over-pressure level.

If there is a leak, the cycling time or "pulse interval" stabilizes at a rate which compares to the leakage loss.

If there is no leak in the system, the cycling time or "pulse interval" becomes longer.

The "pulse interval" is measured by the ECU, which determines whether or not the leak exceeds a defined threshold. Several "pulse interval" measurements are carried out to secure the test.

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Canister Purge Valve Check

When the tank system is tight or the leak measured is smaller than a defined threshold the same approach of the leakage detection is used. The purge valve is opened and each time the reed switch level is reached the LDP performs a pump stroke in order to maintain the pressure in the tank system.

If the canister purge valve is not blocked the cycling time or "pulse interval" becomes shorter. In this case the purge valve operates correctly (not blocked).

If the canister purge valve is blocked in a closed position or the connection tube canister/valve is pinched the cycling time or "pulse interval" remains long.

The "pulse interval" is measured by the ECU, which determines whether or not the purge flow exceeds a defined threshold. Several pumping cycles are carried out to secure the test.

General Overview

The fuel system diagnosis shall monitor the fuel delivery system for its ability to provide compliance with emission standards.

This diagnosis is continuously performed if entry conditions are fulfilled.

The fuel system diagnosis checks if the sum of short-term fuel trim (only based on upstream sensor voltage monitoring) and long term fuel trim (one additive and one multiplicative term) are within a band.

Out of this band a failure is detected.

Different fuel system problems may occur

Scheme 99

1. Fuel pressure problem: short term fuel trim deviation which induces emissions problem, but no effect on the catalyst window set point because of homogenous mixture, in steady engine conditions.
2. Cylinder misdistribution problem due to injector failure: short-term fuel trim deviation with effect on the catalyst window set point because non-homogeneous mixture.

The upstream sensor will cause emission increase when its response time increases too much (AIF Loop period or frequency check).

The period of the A/F loop is measured and the number of lean/rich transition are counted. The sum of valid periods is then calculated. The corresponding limit period versus operating point (N, MAF) is acquired.

A failure is declared when the sum of the measured periods exceeds the sum of the corresponding limit.

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Description Of The Strategy

O2 sensor monitoring is a sequential diagnosis made on steady state conditions.

The diagnosis is composed of two main phases: Measurement Diagnosis and Measurement Phase.

The algorithm is based on the period measurement (starting from lean to rich sensor transition). To avoid non-representative measurement, the period is valid only if the sensor has been below a low threshold and above a high threshold between 2 consecutive lean/rich transitions.

If one of the diagnostic conditions is not met, the test is stopped and the system returns to the OUT OF DIAGNOSIS state.

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Diagnosis Phase

The sum of the periods is compared to limits values. to declare a failure.

Typical behavior of the period criterion versus NOx emissions for instance.

If O2 sensor diagnosis conditions are fulfilled, the system informs the general OBD sequencer and waits for its authorization to start measurement phase. The OBD sequencer manages the priorities in case of multiple diagnosis requests (catalyst diagnosis and O2 sensor diagnosis).

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General Description Of Thermostat Monitoring (Test Group 2BMXV01.6R50, 3BMXV01.6R50 & 3BMXV01.6R5R)

Task of the coolant thermostat is to effect a quick engine warm up after start. The thermostat is closed after engine start to limit the cooling-liquid circulation until the thermostat regulating temperature is reached. The thermostat opens at this temperature and the limitation of the cooling-liquid circulation is finished. If an opened stuck thermostat occurs, the cooling-liquid circulation will not be limited after start. That means an increase of the engine warm up time and can cause emission increase as well.

To monitor the thermostat function, a modeled value for coolant temperature is used. This monitoring is only used for diagnosing a thermostat stuck in the open position. The actual coolant temperature is compared to the modeled coolant temperature, When the modeled temperature has reached normal operating temperature it is then compared to the actual coolant temperature. If there is a large discrepancy the thermostat is declared stuck open.

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General Description Of Thermostat Monitoring (Test Group 4BMXV01.6R50)

The purpose of the coolant thermostat is to effect a quick engine warm up after start. The thermostat is closed after engine start to limit the coolant circulation to the radiator until the thermostat regulating temperature is reached. If the thermostat is stuck open, the coolant circulation will not be limited after start and the engine warm up time will increase. This may cause an increase in emissions.

To monitor the thermostat function, a value for coolant temperature is calculated. This monitoring is used for diagnosing a leaking thermostat or a thermostat stuck in the open position. When the temperature model has reached normal operating temperature the actual coolant temperature is checked to confirm that it has been above the normal thermostat opening temperature for sufficient time. If this is not the case the thermostat is declared stuck open.

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PLAUSIBILITY DIAGNOSIS

These diagnosis check that some data acquisitions from different sensors correspond to data acquisition from other sensors under given engine working conditions.

Idle Speed Control Diagnosis

Engine speed deviation from the nominal engine speed set point is monitored when the vehicle is stopped. If the engine is in idle state for a given time and in normal conditions of engine load, coolant temperature, battery voltage and canister vent valve opening and the difference between set point and actual value is too low or too high, then an error is raised.

Camshaft Sensor Diagnosis (Test Group 2BMXV01.6R50, 3BMXV01.6R50 & 3BMXV01.6R5R)

The camshaft sensor signal presents 1 edge (rising or falling) per engine revolution. The position of these edges is known VS. crankshaft long tooth position. A plausibility diagnosis is then performed in order to compare CAM and crank signals. The CAM edge must be in a window of crank teeth in order to declare the CAM signal as valid. If CAM error is detected, sequential fuel injection will run with a constant injection phase of 180.CRK and the engine will run open loop. With 50%, the injection starts right. otherwise. it will impact engine responsiveness. For ignition, each coil is treated every TDC. Knock correction will take a constant value.

Camshaft Sensor Diagnosis (Test Group 4BMXV01.6R50)

The camshaft sensor signal presents one edge (rising or falling) per engine revolution. The position of these edges is known vs. crankshaft long tooth position.

A plausibility diagnosis is performed that compares camshaft (CAM) and crankshaft signals. The CAM edge must be in a defined window of crankshaft teeth in order to declare the CAM signal as valid.

If a CAM error is detected after the camshaft and crankshaft signals have synchronized the engine will remain in normal operation mode.

If insufficient time is available at engine crank to determine the camshaft and crankshaft synchronization before a cam error is detected the correct firing cylinder bank cannot be determed. In this case: the sequential fuel injection will run with a constant injection phase of -180° CRK, and the engine will run open loop. In this condition there is a 50% probability of the injection starting at the correct crankshaft position. This "limp home" condition minimizes the impact engine responsiveness due to excessive time periods between fuel injection and inlet valve opening.

Each ignition coil is fired every TDC. Knock correction will take a constant default value.

Intake Manifold Pressure Sensor Diagnosis

In certain conditions, it is checked that the MAP (manifold pressure) has a coherent value vs. engine speed and throttle opening. These conditions are

1. MAP too low at engine stopped (in these conditions, MAP cannot be lower than the minimum ambient pressure value).
2. MAP too low at idle speed engine running (in these conditions, the engine cannot be run with too low manifold pressure).
3. MAP too low at full load for low engine speed (in these conditions, MAP cannot be lower than the minimum ambient pressure value).
4. MAP too high in deceleration (EMS calibration is tuned so that MAP target value is 200 hPa in deceleration).

In case of error on MAP acquisition, the MAP information will be built up by using engine speed and throttle position information.

Motorized Throttle Diagnosis Controller Diagnosis

In normal conditions, throttle set point and actual value must correspond within a tolerance given by controller performance in worst case conditions (response time, overshoot...). If an error is detected, then MTC H-bridge is switched off and engine speed is limited at 2000 RPM.

Clutch Switch Diagnosis

When cruise is active (clutch switch is only used for cruise control deactivation), it is checked that the clutch sensor does not flag a de-clutched engine.

Coolant Temperature Sensor

After start, a modeled coolant temperature is calculated based on coolant temperature at start, engine speed and load while running, time spent in idle and fuel shut-off. When model temperature (TCO_SUB) reaches the threshold for closed loop activation, closed loop must be activated. Indeed. TCO_SUB is tuned in order to rise much slower than TCO and so permits to monitor the plausibility of the coolant temperature information.

Air Intake System Diagnosis (Test Group 2BMXV01.6R50, 3BMXV01.6R50 & 3BMXV01.6R5R)

This can be divided into 2 diagnoses

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1. Diagnosis 1: detection of air leaks on air filter (before throttle). Ambient pressure (AMP) is learned when engine is stopped from manifold pressure input and in full load by taking into account the air filter pressure drop. This pressure drop is known and calibrated in order to learn ambient pressure without error. If an ambient pressure learning is performed just after start (driver went into full load), this AMP must be consistent with AMP learn when engine is stopped. If an air leak is present in the air filter. pressure drop through air filter is under-estimated and so AMP will be over-estimated.
2. Diagnosis 2: detection of air leaks in intake manifold (after throttle). In the air path, 2 mass airflows are computed (1 @ throttle and 1 @ cylinder). In order to take into account engine to engine dispersions, an adaption will ensure the convergence of MAF @ throttle on MAF @ cylinder. In case of air leak, the throttle will naturally close and so MAF @ throttle (which is computed from throttle opening) will decrease. MAF @ cylinder will increase because of air leak. When the divergence reaches a threshold. an error flag is raised. In case of leak in the air intake system. engine speed is limited to 2000 RPM.

COHERENCE DIAGNOSIS

The following diagnoses check the coherence between two redundant acquisitions

Throttle Position Sensors

For safety reasons, the system has 2 sensors for throttle position. Signals from the two sensors are compared and must be within a given tolerance. 2 errors can be raised

1. Small discrepancy: it is here difficult to identify which sensor is wrong. For safety reasons, the system selects the highest one.
2. Large discrepancy: a plausibility check is performed with engine speed and mass air flow in order to define which sensor check gives the wrong information.

Pedal Position Sensor

In case of discrepancy between the 2 pedal position sensors, the channel giving the smallest value is then selected (torque request will then be naturally under-estimated).

Brake Switches

It is checked if the 2 brake switches give different information, an error is raised. Cruise control is then inhibited.

See also:
• ON-BOARD DIAGNOSTICS
• PLAUSIBILITY DIAGNOSIS
• COHERENCE DIAGNOSIS