I have a misfire on my 2002 Audi A4 3.0 quattro. It only happens around 3000 rpm, cel blinks, then rides back to normal. I have replaced all ignition coils. Do I have a vacuum leak? I also have a coolant leak in the rear of my engine passenger side. I recently replaced my timing belt. Does that have anything to do with it? I have brought this vehicle to two seperate mechanics. One blamed the timing belt. The other one seems like he has no idea. Im lost, I love my Audi but im thinking I shouldnt get another one ever, with all these problems. Any help will be greatly appreciated.

 

best bet is to fix what is wrong first. But easiest way is to check the check valves in the vac li nes. audi has a reputation of them corriding away causing vac leaks.

 

Has it done it consistently since you did the timing belt or it just started at random?

 

Thank you guys for your responses. Its just random. Im going to replace my spark plugs this weekend and check my vacuum line valves as Paul suggested. Hopefully I can find the solution to my problem.

 

There was a TSB for the coil packs on both my Audis (A6 and 2003 A4 3.0). Call your dealer -- you may be eligible for a refund of the costs. I suggest you hit an Autozone and have them pull the CEL codes for you. That might help diagnose.

 

I have the codes show p0300,p0301 and p0303.

 

Once again, if you do the coilpacks and still have the same recurring problem check the ground on the wiring harness, common thing on 3.0s after taken to the dealer.

 

where is the ground located at?

 

Follow the harness, is a finicky job, I believe is on the firewall by the passenger side, I might be wrong though. Just follow the wires patiently and look for any peeled wires along the harness.

 

thanks yall for yall help. I found the problem. My spark plugs were soaked in oil. So Ima replace my valve cover gaskets and plugs. Now the coolant leak, Ive been reading that these 3.0 tend to leak coolant on the rear of the engine at a nipple of some sort. How do I gain access to this "nipple"?