W202 misfire

[Woolie1000]

Hi Guys,
I have just brought my first Mercedes it is a 1999 C200 W202, A lovely car and I am very pleased with it. I have been having problems with a misfire. At first I changed the spark plugs and all was well for about two weeks, then the miss returned. No 2 cylinder plug is sooted up while the rest are clean. I then changed the coil pack for this cylinder and again new plugs. All well for about another two weeks, then the miss returned, I have removed and cleaned plugs also cleaned the connections on the coil packs and given them a light spray with WD40. the missfire still keeps coming back. Has anyone else had similar problems? And can anyone shine a light on what may be wrong.
Cheers Woolie1000

 

[jibcl500]

The leads running from the coil pack to the plug need replacing.

jib

 

[star]

if you have changed or swopped the coil plug ends, try swopping the injector to see if the misfire changes to another cyl.

 

[Uncle Benz]

You say the plug is sooted up - can you clarify it is not soaked with oil??

 

[Woolie1000]

You say the plug is sooted up - can you clarify it is not soaked with oil??

Hi, The electrodes are sooted up that is that they are dry with black soot as if it were not firing. Cheers

 

[Woolie1000]

The leads running from the coil pack to the plug need replacing.

jib

Hi thank you for your suggestion, I was leaning in this direction as my next move. So I will get a set and go from there. Cheers

 

[Woolie1000]

if you have changed or swopped the coil plug ends, try swopping the injector to see if the misfire changes to another cyl.

Hi thanks for your suggestion, I think that this fault is more electrical than fuel. I have a couple of suggestions which I will try first. Cheers

 

[star]

Hi thanks for your suggestion, I think that this fault is more electrical than fuel. I have a couple of suggestions which I will try first. Cheers

no probs, had one car that was overfuelling on one cyl causing the misfire, was an injector.. let us no the result. or wouldn't it be cheaper to have it diagnosed 1st rather than fit a load of parts?

 

[jibcl500]

The C180 I worked on recently had a 50% compression loss on one cylinder and intermittent misfire on two others, 50% compression loss could be seen as misfire, I think in your case its either a failing coil pack or lead, two black spark plugs would show as failing coil pack, one black plug as a lead.
Might be worth running a compression test anyway if you have the kit other wise you could spend a lot of time and money fixing something that aint broke.


jib