My engine is stalling.

[Blom]

First i just want to say i'm sorry about my poor technical english.

I own a 300E  - 87 (W124).
At first the engine only stalled once a month, and only when releasing the gaspedal.
But it has gotten worse.
Sometimes the car starts up fine and there seem to be no problem at all.
But in most cases it's very hard to get the engine running, and the only way to keep it running is to hold the gaspedal down(not pedal to the metal though hehe).
I went to a MB repairing-firm and they said it could be the "airflow-meter"(Is it called so in english?), anyway the one with the round metalplate that get's sucked down by vacuum when pushing the gas).
Well, i replaced mine with another one but the problem is still there.
And those times when it won't start at all, the needle on the RPM-meter make big "jumps" and i can feel a heavy shaking in the car.
A friend of mine told me that it "backfires"(translated from swedish).
There's also a little microswitch seated next to the gaswire(the one with a lever and a little wheel on).
What is that for? It seems it should be triggered then the gaspedal is released but the mechanism that the gaswire is connected to just touches the lever, it never goes far enough to trigger it.

Once again, sorry about my poor english. Hope you understand what i mean.

Thanks, Sven-Bertil

 

[Andy]

Hi Sven

Having replaced the air flow meter (this is the correct  english) you said or intermated you replaced this item. Did you then reset the engine tune? You mention that a "MB repairing firm" said that it could be the air flow meter. Did they check it? There are specific tests to identify problems of this nature & tests which will give a positive or negative result, especially for the air flow meter which is an expensive item. If you have replaced it with another second hand one. How do you know that that is not faulty either. Do not assume that it will not have exactly the same fault.

The switch you talk about with regards to the wheel. If memory serves me correctly is to do with the is the acceleration decel switch. Which tells the KE control unit that the throttle & engine is at idle. This will not be causing your problem.

Suggest you take your vehicle to a compatent garage, with the correct knowledge & experience to identify and locate your problem effectively.

Regards
Andy@www.mercedesservicing.com

 

[Blom]

The "MB repairing firm" measured the resistance on the three connectors on the side of the air flow meter.
I think according to their servicemanual , the ohm value would have a specific value when the round metalplate was pushed all the way down and then rising to 2/3 of that value then the plate was released.

I tried this at home on the second hand part i bought and can't recall the ohm values but i do remember that the ohmvalue went of the scale when the plate was in the middle of the airflow meter.

Well, thanks for the tip, i will take my car to some other garages to see if they can fix this.

PS, Find it odd though, the garage i went to are supposed to be experts on mercedes.
They are even recommended on MB's Swedish homepage.

 

[Blom]

Hi!
I just wanted to say that my problem is fixed!.
It wasn't the airflowmeter at all.

I don't know that the name of the part is called in english but it's the part with the rotor that control the ignition of the sparkplugs.Called "fördelar dosa" in swedish.
Apparently it was in a terrible state.

PS!,
Quite funny that a professional garage in the city specialized in mercedes couldn't find the problem but instead a very small garage on the countryside found it at once.

 

[Blom]

Ah, It's gotten worse!.
The backfiring was fixed but the engine is still stalling.
It was fine for a month, but now the idle isn't uneven it just stalls as soon as i take my foot of the gaspedal.

I have no problem starting the car, but i MUST keep the foot on the gaspedal at all times to keep the car running.

OBS!
However once in a while it runs perfectly.

I think it would be easier if it did this all the time, because when i get my car to a garage , the car always works fine. IRONY!!!

How could it be a matter of adjusting the KE injection when the car works perfectly at some times???

 

[Andy]

Hi,

Sorry to hear the problem isn't fixed. But I am glad in one way. The repair you mentioned before didn't make sense.

Regards

Andy @ www.mercedesservicing.com

 

[Blom]

Hi.
I haven't taken the car to a repairingfirm yet but i just wanted to mention that the problem seem to be gone now that it has gotten colder outside.
Could it be a component that misfunctions when its getting hot?

 

[ROG]

Hello Blom

Was wondering wether you have any new soution for your problem. I have a 230 CE 1988 in Manila and experience the same idle problem every now and then, especially when the car was heated up due to traffice jam and/or started once the engine is still warm (close to 80C). Also consulted specalised MB garages without getting solution.

Thanks and regards

Roger

 

[robatkinson]

I have a similar problem with my 300TE. Cold starting is not a problem, as soon as the engine is warm though it misfires badly. I think it is something to do with a sensor for the fuel mixture. Any ideas on where to start looking?

 

[ROG]

I was able to finally solve my stalling/idle problem. We replaced the over voltage relay and so far everything does well. Costed around 50 US$, might be worth a try.

Regards

Roger