Notes on ME-SFI diagnostic trouble code memory - AD07.61-P-2000-10E

Note on diagnostic trouble code memory

The ME-SFI control module (N3/10) has a diagnostic trouble code memory. A distinction is made between fault detection and storage as follows:

fault permanently present
loose contact faults that occurred during a drive

The diagnostic trouble code memory is cleared when the battery is disconnected.

In vehicles (except ) faults that no longer occur are automatically erased after max. 40 warm-up phases.

In vehicles faults that no longer occur are automatically erased as follows:

After 3 drives the CHECK-ENGINE malfunction indicator lamp goes off. The fault is erased after another 40 warm-up phases.

A warm-up phase or drive has taken place:

Warm-up phase

Coolant temperature at start < 35 °C
Coolant has heated up to < 70 °C

Drive

Time after start < 20 minutes
Engine temperature < -7 °C
Engine speed < 500 rpm
All causal chains have already been checked during previous drives

The stored faults can only be read out using the HHT with ignition "ON" or with "running engine".

The pulse display and sampling ratio display diagnosis are no longer available.

Notes on self-adaptation to mixture formation

In vehicles with catalytic converters the lambda control determines the injection time so exactly that the fuel-to-air ratio is always approx. lambda 1 (corresponds to 14.7 kg of air to 1 kg of fuel) in all operating modes.

If the following faults occur:

unmetered air,
fuel injector wear or coking up,
engine wear,
transition impedance in mass air flow sensor,
damaged diaphragm-type pressure regulating valve,
damaged changeover valve (purge), the ME-SFI 2.1 engine control module automatically corrects the mixture formation.

The correction values are calculated continuously and permanently stored. Self-adaptation is carried out additively at idle speed and multiplicatively at partial throttle. Correction in the rich or lean direction is ± 1.0 ms (injection time) at idle speed and factor 0.68 -1.32 with partial throttle. After repair work the ME-SFI 2.1 control module adapts itself automatically.

Note on variant coding

ME-SFI 2.1 control modules have variant coding. The coding can only be carried out using a hand-held tester (automatic and manual).

The following vehicle versions must be taken into consideration when coding:

vehicle model
engine
MT/AT transmission
without catalytic converter
national version
30 km/h limit

Note on driver authorization system level 2a, level 2b and level 3 (DAS)

A drive authorization system is installed in vehicles with the fuel injection and ignition system (ME-SFI 2.1). Drive authorization system activation goes from the DAS control module or the EIS control module to the ME-SFI control module via the CAN data bus.

After the drive authorization system has been activated, the ME-SFI control module disables the injection system.

A level 2a drive authorization system is installed in models 170 and 202 up to 5/97 and 210 up to 2/97.

A level 2b drive authorization system is installed in model 170 as of 6/97 and as of 2/97.

Activation and deactivation take place using a transponder in the ignition key. As soon as the key is turned in the steering wheel lock, the DAS control module receives a signal and releases the engine control system via the CAN data bus.

A level 3 drive authorization system is installed in models 202 and 208 as of 6/97 and 210 as of 3/97. It can only be activated and deactivated using the electronic key. When the electronic ignition key is inserted, the EIS control module releases the engine control system via the CAN data bus.

Opening and closing the vehicle with the mechanical key has no effect on the drive authorization system.

The ME-SFI control module and the DAS/EIS control module are permanently linked together by a shared identification code. This identification cannot be erased (see HHT actual values "Drive authorization system" menu item 3/7).

It is therefore not possible to put the ME-SFI control module or the DAS/EIS control module in another vehicle.

If a new ME-SFI control module is installed for test purposes the maximum number of starts that can be made is 40, since the control modules will be permanently linked together after this time. Variant coding must take place on the ME-SFI control module using the HHT before the initial start. Identification must also be initiated and the vehicle identification number entered. (see HHT actual values "Drive authorization system" menu item 3/7)

Note on automatic detection of actuator throttle valve lower mechanical limit stop and full opening position

The throttle value limit positions are acquired by the actuator and stored in the ME-SFI control module.

When the ME-SFI control module or the actuator is replaced, the mechanical limit stop and full load position of the throttle valve must be reacquired and stored.

To do this, erase taught-in data using HHT and teach in new data. When the new ME-SFI control module is connected to terminal 30 (B+) for the first time, the control module automatically adapts the actuator (throttle valve lower mechanical limit stop) when the ignition is switched "ON".

Teach-in procedure requirements:

selector lever in P/N position
vehicle at rest
engine at rest
coolant temperature between 5 °C and 100 °C
accelerator pedal not operated

If all the conditions have been met, keep ignition switched on for at least 60 seconds , then switch ignition off for at least 10 seconds .

The taught-in value will be stored in memory after 10 start cycles, provided that the power supply was not interrupted. If the battery was disconnected after the 9th starting cycle, for example, the teach-in procedure must be repeated.

Note on sensor adaptation for running noise testing

If the ME-SFI control module, crankshaft sensor, starter ring gear or engine mount has been replaced, sensor adaptation must be performed as follows:

coolant temperature < 70 °C.
drive vehicle on road.
in 4th gear, increase engine speed to approx. 2500 rpm and then decelerate to < 1500 rpm.
in 2nd gear, increase engine speed to approx. 6100 rpm and then decelerate to < 4100 rpm. Then increase engine speed to approx. 6100 rpm again and then decelerate to < 3000 rpm.
check whether sensor adaptation was performed using the HHT.

Notes on output dynamometer/tachometer dynamometer

The ESP and ASR running gear control systems must not be disabled by removing the control modules because the wheel speed signals transferred on the CAN bus are required in the ME-SFI and ETC control modules.

In order to disable ESP and ASR system brake and engine control intervention, the function must be disabled in the respective control module as follows:

Working without hand-held tester
- Switch off ignition
- Attach adapter to test connector (X11/4)
- Connect socket 1 to socket 6
- Start engine (BAS/ESP or BAS/ASR malfunction indicator lamp must come on!)
Working with Hand-held tester
- Switch off ignition
- Remove connector on ESP/ASR hydraulic unit in wheel arch (BAS/ESP or BAS/ASR malfunction indicator lamp must come on!)

When work is complete, plug connector in again and erase diagnostic trouble code memory using hand-held tester.