Notes on ME-SFI DTC memory - AD07.61-P-2000-10D

Note on DTC memory 

The ME-SFI control module (N3/10) is equipped with a DTC memory. The detection of faults and their storage is differentiated as follows:

• a permanent faults
• a intermittent contact faults, which occur during a trip.

The DTC memory is deleted after terminating the vehicle battery.

On vehicles (except faults which no longer occur are automatically erased again after a max of 40 warm-up phases.

On vehicles, faults which no longer occur are automatically erased as follows:

After 3 trips the CHECK-ENGINE malfunction indicator lamp goes out. After another 40 warm-up phases the fault is deleted.

A warm-up phase or a trip has taken place:

warm-up phase 

• coolant temperature at start < 35 °C
• heating of coolant temperature > 70 °C

Trip 

• Time after > 20 minutes
• Engine temperature > -7 °C
• Engine speed > 500 rpm
• All causal chains were checked during the preceding trips

The stored faults can be read out by the HHT only when  the ignition is "ON" or when the "engine is running".

The pulse display and diagnosis by means of a pulse-duty factor display have been discontinued.

Note on self adaptation of mixture formation 

On vehicles with TWC the lambda control regulates the injection time so precisely that no matter what operating status, the air/fuel ratio is always approximately equivalent to lambda 1 (14.7 kg air to 1 kg fuel).

If faults occur:

• unmetered air,
• wear or coking of the fuel injectors,
• wear to engine,
• transition resistance in the mass air flow sensor,
• defective diaphragm-type pressure regulating valve,
• defective changeover valve (regeneration),

the ME-SFI 2.1 control module automatically performs a correction of the mixture adaptation.

The correction parameters are constantly computed and permanently stored. The self adaptation is conducted as additive when idling and multiplicative for part load. A correction towards rich or lean when idling is ± 1.0 ms (injection time) and for part load it is a factor of 0.68-1.32. After repair work the ME-SFI 2.1 control module adjusts automatically.

Note on control unit coding 

The ME-SFI 2.1 control modules are equipped with control unit coding. Control unit coding can only be performed using the hand-held-tester (manual or automatic).

The following vehicle versions are to be observed for the coding process:

• Vehicle model
• Engine
• Transmission MT/AT
• Without TWC
• National version
• 30 km/h limit

Note on drive authorization system stage 2a and stage 2b (DAS) 

Vehicles equipped with the ME-SFI 2.1 fuel injection/ignition system also have a drive authorization system installed. The drive authorization system is activated by a signal sent from the DAS control module to the ME-SFI control module over the CAN data bus. After activation of the drive authorization system, the ME-SFI control module deactivates the fuel injection system.

A stage 2a drive authorization system is installed on models 129, 140 and 202 up to 5/97 and on model 210 up to 2/97.

A stage 2a drive authorization system is installed on models 129 and 140 as of 6/97.

Activation and deactivation are conducted by means of transponder technology using the ignition key. As soon as the key is turned in the steering wheel lock, the DAS control module receives a signal and enables the engine management over the CAN data bus.

Locking and unlocking the vehicle using the mechanical key does not exert any influence on the drive authorization system.

The ME-SFI control module and the DAS control module are permanently interlocked by means of an identification code. This identification cannot be deleted (see HHT actual values "Drive authorization system" menu item 3/7).

Therefore, it is not possible to install the ME-SFI or DAS control module into another vehicle for test purposes. 

If, for test purposes, a new ME-SFI control module is installed, then no more than a maximum of 40 start-up procedures may be conducted, as upon completion the control modules are permanently interlocked. Before the first start, the ME-SFI control module must undergo a control unit coding using the HHT. In addition to this an identification must be initiated and the vehicle identification number has to be entered. (Refer to HHT actual values "Drive authorization system" menu item 3/7)

Note on independent recognition of the lower mechanical limit stop and a full opening of the throttle valve from the actuator. 

The throttle valve's end position is registered by the actuator and stored in the ME-SFI control module.

After replacing an ME-SFI control module or an actuator the throttle valve's mechanical limit stop and full-load position have to be recorded again and stored.

To this end delete any teach-in data using the HHT and program the new data. For the first-time connection of the new ME-SFI control module to terminal 30 (B+), the control module will automatically run an adaptation of the actuator when the ignition is "ON" (throttle valve's lower mechanical limit stop).

Conditions for teach-in process: 

• Selector lever in position P/N
• Vehicle at rest
• Engine at standstill
• Coolant temperature between 5 °C and 100 °C
• Accelerator not depressed

When all conditions are given the ignition should be switched on for at least 60 seconds  and then following this it should be switched off for at least 10 seconds 

The programmed value is not stored in the ROM until after 10 start cycles, insofar as the voltage is not interrupted. If, e.g. the battery is terminated after the 9th start cycle, the teach-in process will have to be repeated.

Note on sensor adaptation for the balance test 

After replacement of an ME-SFI control module, crankshaft position sensor, starter ring gear, or engine bearing, a sensor adaptation is to be conducted as follows:

• Coolant temperature > 70 °C
• Drive vehicle on road
• 4th gear, increase engine speed to approx. 2500 rpm and shortly afterwards reduce it by decelerating to < 1500 rpm
• 2nd gear, increase engine speed to approx. 6100 rpm and shortly afterwards reduce it by decelerating to < 4100 rpm. Increase engine speed several times to approx. 6100 rpm and shortly afterwards reduce it by decelerating to < 3000 rpm
• Use HHT to check whether the sensor adaptation has been conducted.

Note on dynamometer/speedometer tester 

Ride control systems such as ESP or ASR must not be made inoperable after unplugging the control modules, because the wheel rpm signals transmitted by way of the CAN data bus are required by the ME-SFI and ETC control modules.

In order to switch off the brake and engine control interventions by the ESP or ASR systems, the functions must be disabled in each respective control module as follows:

A. Working without the hand-held-tester 

• Switch off ignition
• Plug adapter onto the data link connector (X11/4)
• Connect socket 1 with socket 6
• Start engine

B. Working with the hand-held-tester 

• Switch off ignition
• Unplug coupling at ESP/ASR hydraulic unit in wheel house (BAS/ESP or BAS/ASR malfunction indicator lamp must illuminated)

Once the job has been completed, plug the coupling back on and delete the DTC memory using the hand-held-tester!