Misfire on cylinder 5; 6; 7; 8 on A8 4.2 petrol 2004

[ivanvag]

The car misfires under load (cold and warm)

Changed so far:
Spark Plugs
Ignition Coils
MAF sensor


Any Ideas ?

[EG-4.0TDI]

The HT leads themselves might be worth a look as they can degrade with age...

[mjhamilton]

There are no ht leads with coil packs

I have read that this can be a sign that the chain tensioner can be failing or the valve timing wheel has an elongated slot


In both cases the replacement can be done with the engine in the car

[turpal]

Time it up to see if all good,only need to be slightly out to cause that.

[mjhamilton]

It is chain driven - can't time it up - those parts may need to be swapped out

[turpal]

You can time it up,just look up.I had a corsa with 1 cam 10 degree out and running rough at idle.

[mjhamilton]

If the timing is out it would mean the sprocket is worn or the chain has jumped teeth

The first can be done in the car but the latter is an engine out job


Corsa with a cam belt is a different beast to a v8 with chain drive which if I recall consist of 4 independent chains and a bunch of guides and tensioners

[ivanvag]

FYI

It was the cam tensioner