Contour Enthusiasts Group Archives Forums General Troubleshooting possible idle solution

I know as of late there seems to be countless members with idle problems. Well I'm not sure on this one, but I might have found a solution.


My brothers subi has been running kinda crappy lately and there wasn't an identifiable source. He took it too a garage this morning and this is what they did. The TPS on a subi is adjustable. So they adjusted it until the car was running properly. It was nothing complicated, and just a basic recalibration.


Well I put 2 and 3 together and got 4. Its not quite the same, but close to what they did with my brothers subi.

I looked my my TB and I'm pretty sure our TPS is non-adjustable. BUT guess what is! The little screw in the TB! The the throttle mechanism is attached to throttle cable. So if you adjust this screw to leave the throttle slight more open/closed would this not adjust the idle for the car?

The only problems I'm wondering about is:
1) The screw is double thread? how can you adjust it?
-Double nuts tightened into each other might work.
2) Will this completely mess with the TPS?
3) ECU must have to be reset because the car will have to relearn the idle.


Let me know what you guys think! Cause I have never seen anyone mention adjusting the screw for the idle.

Back when I was in college for automotive repair ( not to long ago). I cant remember the number of teachers and the number of times they said do not mess with that screw.

There is many reasons not to mess with it.

The computer when relearning or learning idle will see your lowest point say 700RPM, and say okay 700RPM, TPS 0.7V this is idle, then XRPMs and X TPS V this is X amount of speed.

Now if you change the screw and say bump the idle to 900RPM, the computer will be saying okay 900RPM, not quite idle, just gliding along, okay 900RPMs, still not on idle.

The computer will say, well okay I havent seen idle ( 700), but I have seen 900, so okay now 900 is the new idle. Okay now what have you done, now the TPS V for what should be 700, is now 900, this will mess with a lot of things.

This can mess with your TPS sensor and your computer. Driveability problems can and most likely will result.

Another thing the idle was preset from the factory, if it isnt idling correctly the proper way to fix it, is by fixing the problem, not some back alley repair.

The screw keeps the throttle plate from wedging itself in the bore. Open it too much and the IAC will get confused. It needs to control all the air with the throttle shut. In an emergency like the IAC breaks I would open it up so the car will idle. Mark the position with a scribe mark first. I had mechanical idle controls on my old VW suddenly break and I had to do this to drive the car home.
I've seen some TPS sensors with with a little play in them so you could tweek them a little.