Notes on fault memory
The left (N3/11) and right (N3/12) engine control module (ME-SFI) have a fault memory. All faults can only be read out together via the right engine control module (ME-SFI) (N3/12). A distinction between faults and their storage is made as follows:
Faults permanently present
Loose contact faults which occurred on a journey.
The fault memory is retained after the vehicle battery is disconnected.
On vehicles (except ), faults which no longer occur are erased automatically again after a maximum of 40 warm-up phases.
On vehicles faults which no longer occur are erased automatically as follows:
The "CHECK ENGINE" MIL goes out after 3 journeys. The fault is erased after a further 40 warm-up phases.
A warm-up phase or journey proceeds as follows:
Warm-up phase
Engine coolant temperature when starting < 35°C
Coolant heats up to > 80°C
Journey
Time after starting > 20 minutes
Engine temperature > 7°C
Engine speed > 500 rpm
All functional chains were already checked on previous journeys
The stored faults can only be read out using the HHT with the ignition switched "ON" or when the "engine is running".
The pulse readout and diagnosis via the on/off ratio readout is no longer used.
Notes on self-adaptation of mixture formation
On vehicles with TWC the Lambda control determines the injection period so accurately that the fuel/air ratio is always approx. Lambda 1 (corresponds to 14.7 kg air to 1 kg fuel) under all operating conditions.
If faults occur due to:
Leak air,
Wear or carbonization of fuel injectors,
Wear on engine,
Contact resistance in mass air flow sensor,
Defective diaphragm pressure regulator,
Defective switchover valve (purging),
the engine control module (ME-SFI 1.0) automatically corrects the mixture formation.
The correction values are calculated continuously and stored permanently. Self-adaptation is performed by an additive process at idle and a multiplicative process at part-load. The correction towards rich or lean is 1.0 ms (injection period) at idle and amounts to the factor 0.77-1.28 at part-load. The engine control module (ME-SFI 1.0) adapts itself automatically after repair work.
Notes on variant coding
The engine control modules (ME-SFI 1.0) have variant coding. The coding can only be performed using the Hand-Held Tester (automatically and manually).
The following vehicle details are to be taken into account for the coding:
Vehicle model
TWC
Without TWC
National version
Notes on stage 2 and stage 2a drive authorization system (DAS)
A drive authorization system (DAS) is fitted to vehicles with the fuel injection and ignition system (ME-SFI). The drive authorization system is activated by the RCL control module or IR DAS control module via the CAN data bus to the engine control module (ME-SFI).
Once the drive authorization system has been activated, the engine control modules (ME-SFI) render the injection system inoperative. A stage 2 drive authorization system is fitted on vehicles up to 5/96. It is activated and deactivated with the RCL remote control.
A stage 2a drive authorization system is fitted on vehicles as of 6/96.
It is activated and deactivated with transponder technology via the ignition key. As soon as the key is turned in the steering lock the IR DAS control module receives a signal and enables the engine control via the CAN data bus.
Locking and unlocking the vehicle with the mechanical key has no effect on the drive authorization system.
The engine control modules (ME-SFI) and RCL control module or IR DAS control module are permanently interlocked by means of an identification code. This identification cannot be erased (refer to HHT actual values "Drive authorization system" menu item 3/7).
It is therefore not possible to replace the engine control modules (ME-SFI) or RCL control module or IR DAS control module in another vehicle on an experimental basis.
If a new engine control module (ME-SFI) is installed for test purposes, only a maximum of 40 starting operations may be carried out, as after this the control modules are permanently interlocked. Before the initial start, variant coding must be carried out on the engine control module (ME-SFI) using the HHT. The identification must also be initiated and the vehicle ident. no. entered (refer to HHT actual values "Drive authorization system" menu item 3/7).
Notes on automatic recognition of the lower mechanical end stop and full opening of the throttle valves by the actuators
The final positions of the throttle valves are recorded by the actuators and stored in the engine control modules (ME-SFI). After one or both control modules or actuators are replaced the mechanical end stop of the throttle valves and the wide open throttle position must be recorded and stored again.
After the voltage supply is interrupted at terminal 30 (B +), the control module automatically carries out an adaptation of the actuator when the ignition is switched "ON" (lower mechanical end stop of throttle valve).
Conditions for programming operation:
Selector lever in position P/N
Vehicle stationary
Engine not running
Engine coolant temperature between 5°C and 100°C
Accelerator pedal not operated
If all the conditions are met, leave ignition switched on for at least 60 seconds and then switch off the ignition for at least 10 seconds.
The programmed value is only stored in the read-only memory after 10 starting cycles providing the voltage has not been interrupted. If the battery is disconnected after the 9th starting cycle for example, the programming operation must be repeated.
Notes on engine control module (ME-SFI) after the voltage supply at terminal 30 is interrupted
The following conditions must be met if a cylinder balance test is required after the voltage is interrupted:
Engine coolant temperature > 80°C
Drive vehicle on the roller dynamometer in selector lever position 4 or on the road in selector lever position 3.
Increase engine speed to > 3500 rpm and then reduce to
< 1200 rpm on the overrun.
Repeat operation at least 3 times.
Notes on chassis dynamometer/speedometer tester
The ESP chassis control system must not be rendered inoperative by disconnecting the control modules because the wheel speed signals transmitted via the CAN data bus are required in the engine control module (ME-SFI) and Transmission control module.
To eliminate the brake/engine control intervention of the ESP system, the function in the respective control module is to be cancelled as follows:
A. Working without the Hand-Held Tester
Switch off ignition
Connect adapter to data link connector (DTC readout) (X11/4)
Connect socket 1 to socket 6
Start engine (the ESP malfunction indicator lamp must come on).
B. Working with the Hand-Held Tester
Switch off ignition.
Disconnect front axle VSS sensor connector
(the ESP malfunction indicator lamp must come on).
Once the work is complete, reconnect the connector and erase fault memory using the Hand-Held Tester!
Note on actuation of the "CHECK ENGINE" MIL ( only)
In the event of misfiring (e.g. ignition or mixture) the "CHECK ENGINE" MIL flashes. This involves fault codes to .
The MIL is permanently illuminated for all other faults.
Notes on sensor wheel adaptation
After replacing the engine control module (ME-SFI), sensor wheel adaptation (= program the increment wheel) must be carried out as follows for a cylinder balance test:
Engine coolant temperature > 70°C.
Drive vehicle on the road with 3rd gear or in selector lever position 3.
Increase engine speed to > 3500 rpm and then reduce to
< 1200 rpm on the overrun.
After replacing the crankshaft speed sensor, starter ring gear or after replacing an engine, the sensor wheel adaptation must first be reset using the HHT and then the driving cycle carried out as described above.