E220cdi problem - MAF? - Lambda? - thoughts

[egrid1]

Hi

I have a problem on E220 CDI (2001), on 103,000 miles with full MB service history, last service about 3,000 miles ago.

Symptoms started today are intermittent, and not always present (they seemed to clear after a short run on the motorway) but have returned.

At idle engine is very lumpy at times, and slow to pick up - I thought it had stalled once when I pressed the accelerator from standstill (automatic), then suddenly it lurched forward. In neutral you can see the rev counter flicking up and down at times.

Seems ok over about 20 or 30 mph.

Some smoke from exhaust when problems are present.

I would like to rule out the MAF sensor, as this seems to crop up as a possible problem in the forum. Some have suggested trying the car with the MAF sensor unplugged - If I remove the plug, what should I expect to happen on driving if the MAF is at fault / is not at fault?

There also seems to be a question as to whether a lambda sensor is fitted to the diesels - does anyone have a definitive answer?

Any other thoughts as to what may be the problem?

 

[ciscokid]

This may be what I have on my e220 cdi (yr 2000 164Kmiles).

Check to see if you've got a leak on one of your injector seals (lift the cover and you may see carbon deposits).

From what I can tell from other posts, the only real cure is new injectors and seals although replacing the dodgy seal may get you fixed on a temp basis.

 

[brandwooddixon]

I would like to rule out the MAF sensor, as this seems to crop up as a possible problem in the forum. Some have suggested trying the car with the MAF sensor unplugged - If I remove the plug, what should I expect to happen on driving if the MAF is at fault / is not at fault?

If your MAF is faulty and you unplug it when the engine is running at its worst then the engine behaviour wont change. If it does then it is unlikely to be the MAF. From experience MAF faults are more readily felt when the engine is under load and occaisionally can only be cleared by restarting the engine.

I would expect your car to have lambda sensors in the exhaust.

Please post the first 6 digits of the VIN as this will give more knowledgable people than me, like Television and Black55, a chance to tell you for sure.

 

[jibcl500]

If the MAF has failed unplugging it with the engine running should stall the engine, if its doesnt then the MAF is ok.
Has the car had a rattle recently? could be a collapsed cat blocking the exhaust.

jib

 

[BlackC55]

It needs to have the codes read and some initial diag really.

There are so many things it could be.

There are no Llambda sensors on your car.

 

[television]

Unplugging the MAF will show different symptoms, they generally run rougher with the original faults not there

 

[brandwooddixon]

I stand corrected. Thanks guys.

Incidentally, just to further my knowlegde. If the MAF has failed, why would disconnecting it cause the engine to run more roughly? Surely it would be running on defaults for the MAF based on engine speed already?