A6 2.8 Quattro Misfire

Newbie Joined: Sep 22, 2011 Posts: 13

I'd not long had my C5 A6 when it started misfiring. It was fine when I test drove the car and for a couple of days after, then it started misfiring under acceleration.

I had a guy working for us at the time who was an ex-mechanic, he had a look and we found that the PCV pipe was shot and then on further investigation I found that the plug chambers were full of engine oil.

So long story short I've changed the PCV pipe and had the rocker cover gaskets changed.

However the misfire is still there - Now I'm thinking Plugs or cables???

How likely is this? I'm on a budget and already getting grief from 'Her in doors' so don't want to be trying shed loads of bits to solve the issue, but do want to find a solution.

Posted: Sun Dec 04, 2011 11:06 pm

I take it you fitted new spark plugs after replacing the gaskets

Newbie Joined: Sep 22, 2011 Posts: 13

Thanks for replying Mike.

Errrr, No they weren't changed, but the more I drive it the less 'lumpy' it seems to get (fingers crossed)

Going to see how it goes for now. Rolling Eyes

Newbie Joined: Sep 22, 2011 Posts: 13

Well despite a few miles the juddering hasn't got any better, So got a chance to change the plugs today. The old ones were reasonable clean, but were sooty (soft, black carbon) with white/light grey deposits on the arms.Which from any online chart I've determined that it's potentially a weak spark.

So - Changed plugs andt all though the pick-up is improved the misfire is still there and if anything is more pronounced, So before I lash out the £70+ for the leads I'd like to be able to rule out some of the sensors that can just be unplugged to check.

I'm thinking that I can't cause any damage by unplugging the MAF and MAS sensors?

There is a sensor on the link pipe that leads from the air filter box and then goes down behind the engine - am I right in thinging that this is the MAF?