Hey everybody, newbie to the board. I've had my 2001 TT Quattro for about 10 months now, and I do everything possible to keep it as beautiful inside and out as the day i bought it. I bought it in Colorado, and when I brought it down to sea level, everything went to hell. I get a "check engine" light if I drive over 100 miles or so. I've noticed a dramatic decrease in HP, as well as my engine making louder noise. I've brought it to 2 Audi dealerships, 3 speed shops, and a Jag shop, and none of them can figure out what is going on. The computer reads misfires on all 4 cylindars. If any of you have had similar experiences, or have any idea what is going on or know how to fix this problem, I beg you to let me know. Thanks alot everybody.

A few other folks with that era car have had the spark plug wiring harness replaced due to improper construction causing misfires. The wires short occassionally to the block. Why would this happen at sea level and not altitude? Dry thin air has more electrical resistance than heavy wet air, i.e. it is easier for a bare wire to spark to the block in heavy wet air.

By wiring harness, do you mean the sppark plug wires themselves?

I have the same car and just took it in for the 80K service to my independent guy. The computer was full of miss fire codes on all cylindars. It seems that the plugs go faster than what Audi recommends in terms of when to replace.

I would give this a try.

I plan to take my car back in in a few weeks to see if we get any new codes stored in the computer. I will post if I ger anything.

Bottom line, welcome to the strange world of the TT -- it has a life and mind all to it's own. You will find that membership in this club will more than pay for itself in one simple posting or just reading every week or so.

Thanks, bmax. I appreciate the info and look forward to hearing what you found out.