baron340

I have a 2.7 a6 with 175k that I've completely rebuilt. The cliffs notes are that it had a timing issue, torched the block; new block, new valves, rebuilt turbos, new water pump and timing components etc. It's now all back together, starts and runs for about 30 seconds. Then it starts to stumble and catch. It isn't throwing any codes or other error lights, and I don't have vag com to look at the data. I've looked for obvious vacuum leaks and haven't found anything, but haven't pressure tested it yet. Is there any other testing I can do before I'm forced to throw parts at it? My hunch says its either MAF related or something with the fuel system. I'm hoping some of you guys night have some good ideas.

Kris Hansen

When it's running for those 30 seconds, is it running smoothly? also, if it stumbles, can you shut it off, and start it up again?

baron340

It seems to run smoothly, but I'm hesitant to drive it very far. I got it around the block succesfully. It has started right back every time but once. I did find a vacuum leak at the throttle body to manifold junction and fixed that. After that, it runs better before crapping out on me. Once it starts to stumble, it acts almost like it has a miss, but I'm assuming if that were actually true, it would throw a code. It doesn't seem to get any worse once it starts though.

CRuby

Related to your MAF sensor hunch & since we both have the same year car (2000); take a look at the inside of your MAF wiring connector and make sure all the electrical clips are aligned. Mine had cracked plastic within the connector which allowed the 4 internal clips to be misaligned, such that some had poor contact with the mating pins on the MAF.
See pic in thread #54: Lexus SC400 Down, Audi A6 Up - Page 6 - AudiForums.com

Considering you rebuilt the engine, I expect you're confident you have the cam chain timing & timing belt timing all set up correctly?