Drezilad@gmail.com

So hello all, I just bought a 91 90 quattro and for whatever reason the check engine light will come on when accelerating in 3rd/4th/5th. Rarely will it ever be in 1st or 2nd. Even if I go wot. When I go wot in 3rd, it will usually send the check engine light on and retard the timing. When I shift however, It goes off until I accelerate past a varying rpm.

My guess is a knock sensor. I am running 91 octane in california. (****ty gas I know)

Just seafoamed the car and changed spark plugs.

I'll go ahead and mix 50/50 101 octane and 91 and see if that makes a difference, but I just want to see if anyone has an idea as to what it might be.
I searched all over and only found slightly similar problems but not exactly the same.

4AudiQ

I have had that in my 95 Quattro since I got the car in 2000.
It seems to be inherent in our 90's.
I have never seen a solution that anyone could give.

varia

91 90 quattro is most likely a 7A 5 cylinder engine while the 95 Quattro is a v6, totally different animal

you should pull the codes. most likely knock sensors. easy to upgrade to the newer(donuts) style, and the proper torquing is very important.