High rev misfire W210 E320 petrol '97

[Hmac]

The old bus is being bothered by a misfire at very high revs, if we've got there by me stamping my foot down (making sure that my progress on the Queen's highway is both safe and legal at all times).

Much reading of the forum leans me towards replacing the ignition leads. So, a quick - possibly stupid - question: how do I detach the leads from the coil packs ? Do I just need to heave even more than I have been doing ? They just do not want to come off.

Flying in the face of all that I have read, the plug end of the leads have not presented any huge problems. Perhaps I've jsut been lucky.

Fuel filter is new, as is air filter. MAF has been cleaned (by me). Current plugs have done 40,000 miles so I hope they will be ok for another 10-20 K.

Any top tips and handy hints greatfully appreciated.

The last time I had to buy 12 plugs was back in the old XJS days. Aaah...there was a nightmare car.

 

[mattuk]

Air intake or vacuum leak can cause it. When u say very high revs do u mean above 4k rpm?

Have u read codes to see what misfire?

 

[Hmac]

I'll check out the rev point in Sainsbury's car park tomorrow (too noisy to do it in my nice, quiet road !).

Is there any obvious pointer for the layman - me - as to whether I should be looking for an electrical or air/vacuum problem ?

 

[robparker]

If you are in park/neutral there is a rev limiter, so you will need to try it when driving.
The leads will pull off the coils, try twisting them a little to help.