slk misfire

[baptistsan]

2005 slk.

Misfire on cylinder 4.

Goes into MB who replace all 6 spark plugs.

Car returned, all is well for a few days.

Misfire returns.

Return car.

Further testing done. Coilpacks fine. Injectors fine.

Car returned with faults all cleared and car running as it should.

This was 2 weeks ago, car running absolutely fine until today.

Misfire has returned.

Car will go back on Monday.

In the mean time, any thoughts?

[baptistsan]

Just back from MB.

Failed coilpack apparently. Now all fixed. We will see!

[Dog Star]

I’m int er rated to know how a dealer could get this wrong in the first place; the car will indicate the errant cylinder, so swapping a coil pack round would show if it’s a coil pack or plug at fault.

[baptistsan]

Agreed.

And this is what they did.

Cylinder 4 misfire initially.

Put that coilpack onto cylinder 1.

2 weeks later, misfire on cylinder 1.

New coilpack and they are saying it's fixed.

We shall see.

Who knows why it took 2 more weeks to completely give up the ghost?!