Testing Motor control unit (ECU) for Mercedes 280 CE (W114 )

This forum has been a great help in sourcing triggercontacts for me MC 280CE (thanks til Norbert Fischer for selling me a set i mint condition!).

I'm hoping for mere hellp, since I'm still having trouble getting my Mercedes 280CE (w114) to run properly.

There have been several problems that have been solved, but new ones have emerged.

The trigger contacts for the injectors were very worn, but they have now been replaced. .

The situation now is that the car starts and idles fine (most of the time). However when it idles it sometimes shuts off. Just as if the ignition was switched off. It can be started again, but it runs very poorly when you run it. As if doesn't get enough gas.

The temperature sensor has been replaced (before it got way too much gasoline). MAP sensor is switched (the sensor has been tested by Bosch classic parts) the throttle switch is replaced with NOS (before you could not hear the clicking sounds when turning the throttle manually). Finally the trigger switches have been replaced (the old ones were very worn)..

Since the car still doesn't run properly, the suspicion is now concentrated by the motor control unit ((ECU)). The suspicion arises as we can hear the nozzles being activated for no reason if the car is left with ignition turned on.It happens randomly and sometimes when the car has been with ignition om for 4-5 minutes.

The electrical connections have been measured and nothing has been found here.

Is there anyone in this forum that can test and possibly repair my ECU? Or mayby can recommend someone that can?

The control unit has number 0280001008.

Hoping that something in this forum can help as my mechanic is about to give up on my car.


Kind regards from Denmark

Per Jorgensen

Hi Per,

of course Bosch Classic can not only repair your MAP sensor - as they did - but also your ECU.

However it sound slike a strange error. Virtual impulses after minutes of ignition being switched off at no reason. That is a new error I have never seen before. I have though seen cars stopping to work and only starting agian when they would be cold. But these fake impulses are new to me. ECU only creates impulses when engine is off and throttle switch signals someone pushed down the pedal. But no one has touched yours. Well that is mysterious and I cannot think of any effect in ECU that could create that.

Just one hint: You are aware that you have to remove your ignition coil lead 1 or 15 while you leave ignition on for several minutes. Otherwise you can destroy ignition control module, ignition coil and power resistors.

Hi Volker

I'm sure that Bosch is able to test/repair my ECU, but I have now been waiting for about 8 weeks for them to get back to my local Bosch servicecenter on a request for refurbishing/replacing my worn trigger contacts (in the meantime Norbert has helped me sourcing a set in mint condition), so I was just concerned that it would take too long time in this corona-situation.

It is indeed a strange behaviour, and we haven't seen this before. My mechanic even tried to disconnect the trigger contacts and the throttle switch, but even though the injectors were "clicking" randomly witth the ignition left on, but nothing else "touched".

Norbert (Nordfisch) very kindly have offered me a ECU . My only concern is, that it's not tested, so I can't be 100% sure, that it's not still the ECU thats causing the problems, if the car will act the same efter replacing the ECU. It is worth a try though (I''m getting a bit desperate now, since the car has been at my mechanic for more than 2 month now).

I was not aware, that the col leads should be removed, when the ignition is left on for longer time, so thanks a lot for your advise, which I'll pass on to my mechanic rigth away (he properbly is aware of it, but better safe than sorry).

Cheers from Denmark

Per

Finally, I got the car running perfectly again.

It was the ECU that was the culprit! The car starts and drives better now than ever before. Thanks again to this forum for invaluable help with both troubleshooting and especially help to source spare parts, that are hard to find.

Many greetings from a (now again) happy Mercedes owner from Denmark

Cheers Per

Hi Per,
thank you for your follow-up.
I think the ECU has been the central problem, but now you have revised or replaced almost every single part of the injection.
I wish you all the best and a faultless future with your car.

Don't throw the faulty ECU away. It could be interesting to analize the problem.
Don't throw away any faulty part.. most of them are rebuildable.

Regards
Norbert