Catalyst Damage BMW M3 E46

Catalyst Damage

1. Within an interval of 200 crankshaft revolutions the detected number of misfiring events is calculated for each cylinder. The ECM monitors this based on load/RPM. If the sum of cylinder misfire incidents exceeds a predetermined value, a fault code is stored and the "Malfunction Indicator Light" will be illuminated.

If the cylinder misfire count exceeds the predetermined threshold the ECM will take the following measures

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1. The oxygen sensor control will be switched to open loop.
2. The cylinder selective fault code is stored.
3. If more than one cylinder is misfiring the fault code for all individual cylinders and for multiple cylinders will be stored.
4. The fuel injector to the respective cylinder(s) is deactivated.

The Integrated Ambient Barometric Pressure Sensor of the MS S54 is part of the ECM and is not serviceable. 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 MS S54 monitors barometric pressure for the following reasons

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1. The barometric pressure signal along with calculated air mass provides an additional correction factor to further refine injection "on" time.
2. Provides a base value to calculate the air mass being injected into the exhaust system by the Secondary Air Injection System. This correction factor alters the secondary air injection "on" time, optimizing the necessary air flow into the exhaust system.

E46 M3 Diagnostic Socket: For model year 2001 the E46 will eliminate the 20 pin diagnostic connector from the engine compartment. The 16 pin OBD II connector located inside the vehicle will be the only diagnosis port. The 16 pin OBD II connector has been in all BMWs since 1996 to comply with OBD regulations requiring a standardized diagnostic port.

Previously before 2001, only emissions relevant data could be extracted from the OBD connector because it did not provide access to TXD (D-bus). The TXD line is connected to pin 8 of the OBD II connector on vehicles without the 20 pin diagnostic connector.

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The cap to the OBD II connector contains a bridge that bridges KL 30 to TXD and TXD II. This is to protect the diagnostic circuit integrity and prevent erroneous faults from being logged.

The OBD II connector is located in the drivers footwell to the left of the steering column.

Special tool 61 4 300 is used to connect to the 20 pin diagnostic lead of the DIS until the introduction of the DISplus.

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Diagnostics via the OBD II Connector

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Before any service work is performed on any fuel system related component, always adhere to the following

1. Observe relevant safety legislation pertaining to your area.
2. Ensure adequate ventilation
3. Use exhaust extraction system where applicable (alleviate fumes).
4. DO NOT SMOKE while performing fuel system repairs.
5. Always wear adequate protective clothing including eye protection.
6. Use caution when working around a HOT engine compartment.
7. BMW does not recommend any UNAUTHORIZED MODIFICATIONS to the fuel system. The fuel systems are designed to comply with strict federal safety and emissions regulations. In the concern of product liability, it is unauthorized to sell or perform modifications to customer vehicles, particularly in safety related areas.
8. Always consult the REPAIR INSTRUCTIONS on the specific model you are working on before attempting a repair.

The DISplus/Modic as well as a reputable hand held multimeter can be used when testing inputs/components.

It is best to make the checks at the ECM connection, this method includes testing the wiring harness.

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The correct Universal Adapter for the MS S54 application should be used (#90 88 6 121 300). This will ensure the pin connectors and the harness will not be damaged.

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When installing the Universal Adapter to the ECM (located in the Electronics Box in the engine compartment), make sure the ignition is switched off.

When checking the fuel tank and ventilation system for leak-tightness use Special Tool Set #90 88 6 161 150 which includes all of the pieces shown to the right.

This set is used in conjunction with shop supplied compressed air and the DISplus Multimeter function for reading the pressure bleed off.

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This Special Tool Set #90 88 6 161 160 will also be required to "cap off" the DM TL air filter and Evaporative Emission Valve hose when performing the Leakage Diagnosis Test.

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If the test indicates excessive bleed off a leak detector should be used to check for leaks at

1. Fuel Filler Cap and Filler Neck
2. Fuel Tank Ventilation Lines
3. Evaporative Emission Valve
4. Fuel Tank and Fuel Sending Unit
5. Liquid/Vapor Separator

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Sport Switch: The MS S54 ECM contains two different throttle progression program curves (Sport and Normal). The sport program is selected by pressing the Sport switch located in the center console switch panel.

The switch provides a ground signal (input) to the ECM when pressed. The MS S54 activates the sport characteristics for the EDR throttle control. This provides an increase in throttle opening and response time over the non-sport position.

Power Transmission Switch: The power transmission switch (circuit) consists of two switches in series. The circuit includes a clutch switch and a gear selector switch on the transmission. The functions of the power transmission switch are as follows

1. Cutout for cruise control operation
2. Enable condition for idle control

The switches provide a high signal for the MS S54 when the clutch is disengaged and the transmission is in gear. If either the clutch is engaged or the transmission is in neutral, the cruise control will be disengaged.

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Cruise Control: As with other electronic throttle systems, the MS S54 ECM takes over the function of cruise control. Throttle activation is provided by the MS S54 electronic control of the EDR Actuator and monitoring of the feedback potentiometers.

All driver requested cruise control function requests are provided to the MS S54 from the MFL II control module in the steering wheel over a single FGR data lead.

Oil Temperature/Level Sensor: The electronic level sensor is located in the engine sump mounted to the engine oil pan. The probe of the level sensor contains two temperature sensing elements.

1. One senses the engine oil temperature.
2. The other is heated to 10°C above the temperature of the engine and then is allowed to cool.

The length of time it takes to cool the heated element is how the sensor determines the engine oil level. When the oil level is high it covers a larger portion of the probe submersed in the oil sump. The engine oil around the probe absorbs the heat of the heated element quicker than if the level is low.

The microprocessor in the base of the sensor produces a pulse width modulated signal proportional to the oil level. The pulse width increases with a decreased level of oil.

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Based on the oil temperature, the visual warning LEDs in the tachometer will illuminate at cold engine start up and slowly be extinguished as the oil temperature increases. One amber and the red LEDs always stay illuminated reminding the driver of maximum RPM zone.

The oil temp sensor also serves as a vital input for VANOS operation, varying the solenoid control based on oil temperature (reaction time of camshaft movement). In the event of a fault the engine coolant temperature is used as a substitute value.

Electric Cooling Fan: The electric cooling fan is controlled by the ECM. The ECM uses a remote power output final stage (mounted on the fan housing). The power output stage receives power from a 50 amp fuse. The electric fan is controlled by a pulse width modulated signal from the ECM.

The fan is activated based on the ECM calculation of

1. Coolant outlet temperature (monitored by the Radiator Outlet Temperature Sensor)
2. Calculated (by the ECM) catalyst temperature
3. Vehicle speed
4. Battery voltage
5. Air Conditioning refrigerant pressure (calculated by IHKA and sent via the K-Bus to the ECM)