Hello, I have an 1987 s4 Tii.

I just had a fresh rebuild on the car, it drives great, and runs really nice on startup. It will idles at 750-1100 (Cant remember right now) on start up, but once it is fully warm, it drops to around 500 and sounds like it is running on one rotor. Where should I start first. Fairly certain I am good on vacuum, as I capped what is necessary with silicon caps, and replaced the old vacuum lines, one at a time. I never adjusted the idle after rebuild, just timing.
What should I start by checking? Idle, Plugs, Thermowax system on throttle body??????

Mods are
Rtek 1.7
Racing beat rev TII exhaust
720 cc secondary injectors - New
550 cc primary injectors - New
- Also put in new fuel filter, pump, sock, and lines. Parallel fuel system with Aeromotive FPR at 40 psi
Stock airbox

any help is appreciated, I think I will check the TPS tomorrow.

 

always a good start, basics first and then go from there.
i'd check the timing, and then make sure the trailings are firing too.
then you can set the idle mixture and some BAC valves are adjustable and you can try that.

after that you're looking for vacuum leaks

 

Have you had any luck solving this issue yet?

 

haven't checked yet, been waiting for some exhaust parts to get in. Prolly get to it sometime next week, I'll keep the thread updated.

 

any luck in sorting out this issue yet? My car is behaving similarly and I am curious to see if you have had any luck. Thanks!

 

Yea! So I decided to check my spark plugs. It is about 60 miles after the rebuild and very light cruising. The spark plugs were black, and had assembly grease on them. Cleaned them off, and it worked like a charm

 

thanks! I have been planning to pull plugs for compression test anyway so I'll change them when I do that!