All of the coils and sparkplugs are new and I tested the injectors and swaped Cyl 4 injector with cyl 1. I cleaned all of the connections and greased them. The car is running smoother but I just got another CEL. It only hapens on start up once in a while. I tried monitoring it with the Vag-Com and I get nothing. Where to go from here?

 

I'm going to test the fuel system first. I think it's loosing pressure too fast so probably can't build pressure fast enough either. I pulled a P0300,P0304 before and Cyl 4 is last in line.

 

AMP ignition pack, it is located on the top of your airbox. How many miles are on the car? This commonly goes out and all it controls is your cylinders. Also, I would possible look under your car and find the fuel filter and find the date on it if you can. This can sometimes cause a misfire. Commonly these aren't replaced on some audi's ever, even in 100k miles + (over looked). I would honestly lean towards the amp ignition pack.

 

113K on it and new fuel filter. I'll look into the Amp Ignition Pack. Thanks

 

Down below - edit

 

3.0L engines don't have ICM (ignition control modules) seperate from the coil packs themselves, so that can't be the problem. When monitoring the vag com at idle you say that there are no misfires with the engine running?
You PM'ed me this fault code:
17924
P1516
Intake Manifold Changeover Valve circuit Open

Which i think is the cause of the random misfires. The 3.0L has a motor built into the intake that changes the intake runner lengthes (like a VR6)so if the engine management is requesting a certain length of intake runner and isn't getting the correct amount of O2 into the combustion chamber it will freak out the engine management for a second causing a misfire. Once the ECM adapts, it will cease misfiring. You should find out whats wrong with the manifold change over valve.
Best i can come up with, the fuel injectors wouldn't be the problem, the fuel pump is possible but a quick fuel pressure test can rule that out.

 

Thanks, I'll test the fuel pressure quick to get that out of the way and out of my mind. I'll get up to date on the changeover valve and see what I can find wrong with it.

 

So I originally though that the change over valve was unrelated because I had disconnected it and moved it around when I was pulling the fuel rails, checking the injectors. And I was almost right it was unplugged. I probably didn't get it to latch correctly (they are so brittle I’m afraid to push on them). But upon closer scrutiny I found it! The Vac line to the crossover valve had been replaced and someone used a T splice. and must have capped the unused section which later cracked off causing a Vac leak to the Changeover Valve. How "F"ing lucky am I to not have plugged that in right or forces from above unplugged it for me because that code was not coming up before. I cleared the codes and started the car none came back up. I’ll check them again this weekend. I'm going to R+R all the Vac lines this weekend they look tired.

By the way the Terminal connectors on the 2000 A8 with the push in metal clips are so much nicer. I was so happy to see those. I was even happier to remove them without breaking any.

 

Auditech79, Thanks, I'm going to buy you a cape!

 

I don't know if i need a cape, but thanks.