Intermitent misfire

[BenzComander]

Just replaced the MAF, and still the problem persists.

Car now has new plugs, leads and MAF, now where??

Suggestions please

 

[Glenn Smith]

Does this car have any kind of exhaust gas recirculation system on it? A faulty valve can cause similar problems to faulty mas, ie too much exhaust gas equals low airflow sensing giving less fuel and week mixture, although my experience with this is on diesels i would think the effects are as bad if not worse on a petrol engine.

 

[BenzComander]

Not sure, somebody mentioned Lambda sensor a while ago, but not sure how to check this!

 

[Birdman]

Just replaced the MAF, and still the problem persists.

Car now has new plugs, leads and MAF, now where??

Suggestions please

Do I owe someone a fiver?

That leaves coils and fuelling, I suppose. Have you checked the air filter isn't blocked?

 

[BenzComander]

Do I owe someone a fiver?

That leaves coils and fuelling, I suppose. Have you checked the air filter isn't blocked?

Just PM me your credit card details

Air filter was OK, as had it out when changing the MAF.

Was wondering about coils, are the coils/ignition modules the six black boxes on the cam covers?? Sorry to sound so dim!

 

[Birdman]

This show the coil packs. I found it on an illustrated 'how to' thread which is worth a looksee, at:
http://forum.mbworld.org/forums/showthread.php?p=1879878

 

[Brian WH]

Also worth checking the coil pack wiring for signs of chafing, sparking or wear etc before spending money replacing the coils.

 

[BenzComander]

Also worth checking the coil pack wiring for signs of chafing, sparking or wear etc before spending money replacing the coils.

Thanks Brian, is there any particular area of the wiring to check that is a known chafing point? As the wires are enclosed in a plastic sleeve.

 

[Brian WH]

Thanks Brian, is there any particular area of the wiring to check that is a known chafing point? As the wires are enclosed in a plastic sleeve.

Just check the ends where they bend and any location they could rub against. If properly sleeved they should be OK.

 

[bibamus]

I`d be interested in what is causing your problem. ( sorry, I am not going to offer solutions here, just moral support) sounds exactly like mine (W202) Everytime I changed something, it would run fine for a while, then back to misfiring.
I changed Maf, plugs, leads, coils, o2 sensor ( Lambda) fuel filter and pump, still doing it. I suppose its injectors or fuel rail next!!

Keep going, the answer is out there....

Allan