I opened the screw on the top to increases the idle to keep it from dying when put into neutral.

 

Check for vacuum leaks, and calibrate your tps

 

Also to adjust that screw properly, you need to jump a connector near the airbox, otherwise you're essentially doing nothing.

 

Even if its the non turbo? I swear the manual says you only have to use the jumper wire for turbo'ed models.

 

Shoot, I don't even think the TIIs have that screw... I've only adjusted it on NAs.

 

Are you referring to the screen that's close to the map sensor?

 

Green one.

 

 

Try turning up your idle.

 

I did, i'm wondering if this issue is a symptom of a bad BAC?. The idle will only start to hunt when the engine is under load. Like when pressing on the brakes or rolling the window down.

 

Let the engine idle. Spray carb cleaner around the intake manifolds. If the idle changes you have a vacuum leak.

 

We tried that. Nothing changed until we actually created a vacuum leak. Then the idle became smooth

 

 

I mean if you have no vacuum leaks, id double check the tps when your having the condition. Also look at the throttle linkage while the engine is running, make sure it's not partially open. See if you can close it more.

 

 

Still confused as to why having a vacuum leak makes my idle stable and not hunt..

 

 

If your car is a s4: To set the tps, bring the car to operating temperature. Unplug the tps. Using a multimeter measure resistance between the black and green wires. Turn the adjustment screw until you reach 1k ohm. While you're at it slowly run the throttle to 100%, it should gradually reach between 4-6k and ohm.

if you're concerned about the BAC being bad, unplug it, the car will idle fine without it, that should answer that quickly.

 

 

Idle is steady at 1300 when warm. When the car is warming up the idle surges up and down. Any ideas?

 

Thermowax fast idle cam.