My g/f has a 98 TA A4 that i just installed headers on. After the install we were having trouble with the o2's and got those squared away. It ran fine for about a month and all of a sudden it started running like crap. When the problem came back she gave it gas and it went no where but got loud like it wanted to. This went away after that one time but it has been running weird since. Tonight she was sitting at a light and the idle dropped down and it almost died. There is no ses light and i have gone back over all the wiring o2's and plugs and wires and every thing seems ok? Any thoughts on why the weird idle or running like a 6cyl?

Thanks for your Help Chris

 

did the bolts back out? could be a nasty exhaust leak.

 

burned one or more plug wires on the headers, you really have to be careful with the routing and may need to add some heat shielding.

Probably runs ok at idle when cold, but quickly gets worse as the motor heats up or when you put a load on it.

 

I put a new o2 in it today it was reading a little out of range. It was raining here today so i couldnt steal her car and see if it made and difference. I think the coating on the lt headers might have killed it.
Ill keep you up to date.

Chris

 

maybe a problem with your fuel system that just went bad at remarkably the same time your headers were put in! But thats just a far off guess..

 

i also have pacesetter headers. Those bitches will not stop leaking. A nasty exhaust leak can cause the o2s to read wrong.

 

For some reason(this is a longshot), I think it might be tranny related, you said she gave it gas and it just revved up like it was in neutral? But take that as a last resort, see if theres any exhaust leaks and slap a fuel pressure guage on that bitch and clean the injectors. Might have to find someone with a real good scanner too, check the TPS(throttle position sensor) that can make things screwy also.

 

o2 replaced its better but not perfect. it kicks down when it wants too, but not when u want it too exhaust doesnt seem to be leaking going to check tps soon.

 

yea check the trans... mine did the same thing and I ended up with a burned 3-4 clutch band and a $1500 bill.