rs695

I've got a 2006 A4, 89k miles, that's misfiring badly on the 4th cylinder, mostly at high speeds (60-70 mph). We've ascertained that it's not the spark plugs or the ignition coils -- both are fine, and we changed the plugs to be sure. Had the PCV and cam follower swapped out about two years ago. All that seems to be left is the low pressure and/or high pressure fuel pump. The high pressure has a TSB, so if that it's, Audi pays; however, the TSB calls for a check or replacement of the low pressure fuel pump, which ain't cheap. I'd like to avoid that.

Am I on the right track? Any other culprits you all can think of?

Prospeeder

Well i must ask have you compression tested #4? If its got low compression than it will misfire under a heavy load. Injectors are known failure items on these direct injected engines also.