Misfiring - driving me nuts!!!

[almacg]

Hi

Help I have a 98 C230K auto sport, 115 on the clock. The problem I have is an intermittent misfire caused when I accelerate or try and use the kickdown. Basically it occurs when I dont drive it like a volvo!!. It can happen from stationary or when at 70.

I had a diagnostics done which found a misfire on No4, this cleared as soon as you switch on and off - unfortunately the diagnostics give no indication as to what causes the misfire on No4 !!

I have replaced the MAF and although the MAF wasn't dirty have replaced the crankcase breather valve below the intake manifold just in case. These both made an improvement but has not solved the problem.

Any suggestions would be gratefully received as its really getting to me - Thanks

 

[Ian B Walker]

I have just had the very same problem with a 230k. Its your coil packs. Change them as a pair. £69 each from your dealers.

 

[bigasotonuk]

Hi,
I had a similar fault with my 230k and was gonna replace a coil pack but thought i would replace the ignition leads first (complete kit is 2 plug caps and 2 leads bought them from ECP). This cured it.
Apparently the c class suffered from failing coil packs, but i don,t really see the need to replace both of them.

 

[almacg]

Thanks very much guys - no mystery as to what I'm upto at the weekend !!

 

[busby20]

My C Class had this problem, I tracked it down to the lead at the coil end-corroded and the terminal post was shot. Replaced one coil - be advised- a real pain to get at.

 

[C220GJS]

My C Class had this problem, I tracked it down to the lead at the coil end-corroded and the terminal post was shot. Replaced one coil - be advised- a real pain to get at.

If your's has the coils mounted under the inlet manifold they are not as prone to failure as they don't overheat like those mounted under the cover on the head, but the downside is they are near impossible to get at.