cutout problems

[beastie]

My 1991 300E automatic has developed an intermittent cut out problem which even the local dealership admit they cannot resolve. The car runs beautifully, is well looked after (we're in the trade!), but every so often when slowing down or accelerating away, the engine cuts out and dies!! At traffic lights sometimes you can feel the engine go "lumpy" before it dies, like an irregular tickover, before it cuts out. It usually starts straight away, but sometimes can take two or three times. After a few days the problem will correct itself and we believe we have solved it. It has been tested to within an inch of its life and nothing has turned up (except a dodgy rotor arm which has been replaced). Has anyone else encountered this problem? My local dealership says they have had three in - same model same year - but have failed to resolve it. Any constructive help would be appreciated.

 

[andy_k]

is yours one of the cars affected by the bio degardeable wiring loom issue?

One of the first signs of the harness failing can be random cut outs and faults.

I'd do a forum search on wirng harness to see if any of the symptoms sound familiar.

Of course I could be completely wrong here

Andy K

 

[mjtray]

Beastie,

Your car will not be affected by the dodgy wiring harness problems.....it only applies to M104 engined cars, and yours is a M103 engined car.

The problem you describe sounds very similar to a problem that I have had with my E280 (1993). Car would cut out randomly...normally after running at speed and then slowing down. Would often be hard to start if I had just switched off.....I would have to leave it for a couple of minutes and then churn away before it would fire.

The problem turned out to be the Over Protection Relay. Now I'm not sure whether the OVP Relay is just fitted to M104 engined cars. Its located behind the battery and behind the plastic panel which protects the ECU. Its just to the right of the ECU, its about 3 inches high and has a small plastic cover over it. The original OVP's had the following serial No 000-540-52-45 and are known to be a faulty design. The replacement OVP you need has a serial No 000-540-67-45. Cost £45.00 from my local Merc dealer and is easy to replace once you have taken the battery out.

Since I have replaced the OVP the car has run like a dream.

Hope this is of help and apologies if it does'nt apply to M103 engines.

Cheers

 

[John Peerce]

Could it also be the MAS (Mass Airflow Sensor) ? my car (although a later 1999 model W202) developed similar sounding symptoms... cuts out at traffic lights, (once cut out while is was in motion at 60mph). I narrowed the problem to three causes : 1) Crank position sensor 2) Over Protection Relay, 3) Mass Air Sensor.

In the end the Mercedes specialist replaced the MAS (cost £228) and so far the problem has not occurred again.

 

[LukeHayler]

same problem with my 1991 190E

i have the same problem with my 1991 190E - very very similar to beastie's and mjtray's symptoms (ie, cutoff when slowing down from speeds, "lumpy" engines etc).

i am not sure what sort of engine my car has (M103 or M104) as i would hope the OVP solution would work for me rather than the MAS one

Does anyone have any ideas?

 

[Andy]

Hi Beastie

You say the vehicle has been tested within an inch of its life. I would suggest one of the following is the problem & only the last one cannot be effectively tested for unless it is exchanged and tried.

1.Idle contact check for switch & high resistance.

2. Air flow meter potentiometer. This is a common one. Again it will show up on test. Even the slightest irregularity it should be changed.

3. With reference to the No1. The throttle flap should be clean making sure all vacuum pipe holes are clear.

4. The ke control unit.

One of these should be causing the problem or associated wiring.


Good luck!!

Luke

Your vehicle is fitted with a 102 engine.

You could try the above in try to resolve your problem. Your vehicle is NOT fitted with a air mass sensor.


Regards

Andy @ www.mercedesservicing.com

 

[Phynyxun]

My father had this problem on his 1999 500 SL, the problem turned out to be a fault in the exhaust system.

There is a sensor somewhere in the exhaust for some reason, and it had failed. Producing an irregular tickover. Leading to a cut out, the problem then was starting it back up. Took around 3 minutes. trying the starter every 10 seconds or so.

 

[LukeHayler]

Thanks Andy, when you said "You could try the above in try to resolve your problem." - did you mean changing the OVP? or the solutions 1-4 raised by you? Where exactly is the OVP in the 1991 190E and what part number should i look out for? Is it easy to get to and change?

 

[13022]

The Overload Protection Relay is behind the battery. (Theres a black plastic panel that you need to remove behind the battery to get to it) If its like mine it'll be on the left of the ECU. (Although replacing it hasn't sorted out my 190E)

 

[Andy]

Hi

The solutions 1-4

Regards

Andy