So I just bought this 96 a4 quattro last week and I realized a couple days ago that it's running really rich. I can smell unburnt gas from the tailpipe pretty bad and the pipe is getting blacker everyday. I've tried to run a code reader on it and the EGR system check keeps coming up incomplete. Could it be that the car isn't hot enough when I test or what? Is there a sensor that I can check before replacing the EGR valve because it's like $300 at least for the EGR. I say EGR because when I bought the car the previous owner suggested that it might have problems. I replaced all the vacuum lines today to eliminate that issue. What's next? Does anyone have a diagram of the vacuum system? Thanks in advance.

 

teh 12v has a really comlicated vac line setup, best bet is get about 5 feet of silicone tubinga nd replace one line at a time, take some time but you know everything hooke dup right. i may have the same problem as you with the car running rich since my cars been backfiring when i engine break. but it may also be due to a bad ect i had a while back. if your sure its the EGR chances are its jsut clogged with carbon, take it out and spray the hell out it with WD-40 let it sit and put it back on, this is usally the first step before actually haveing the change the thing.

 

I did the vacuum lines today and everything came out fine. The thing that gets me is that the car runs beautifully, nothing lost in power and still very responsive, does that mean anything or is that normal? What is a "ect" Sorry I'm a noob with the Audi I've had Chevy trucks for 10 years.
[Quote "but it may also be due to a bad ect i had a while back."]

 

the ect controls the tempreture gauge but also tell the ecu how much fuel to put in if the car thinks its still cold its going to use more fuel and therefore run rich, if your temp gauge goes up to normal relavtivly quickly you should be ok. otherwise everything you said sound normal, but if the code for the egr come up again it means the butterfly flap in it has stopped working usually due to carbon build up and need to be replaced or wd-40ed. ive been driving with a an egr code for almost a year now, and nothing seems out of the normal.

 

Initiall I had ruled out the ECT because I kept checking my temp gauge and it would always warm up normally. But tonight as I was driving home I realized that the temp gauge I was looking at was the oil gauge and I saw another temp gauge up top by my fuel gauge. So then I realized that this gauge was reading cold, dead cold, even though I had been on the freeway for 20 minutes. So obviously this is the coolant temp gauge and it's not registering when the car is hot. 2 plus 2 equals ECT switch bad right? I'm gonna change it out in the next couple days and seeif that helps but it makes sense doesn't it?