Idle issues
 

Finally got my car back together after replacing a few solenoids and polishing my UIM, y-pipe and TB....Damn does it look sweet... And the solenoids have seemed to fix my boost issues. I get a little bit of cut out in first gear at high rpm but second and especially third are just so damn strong.

Anyway, my issues now are directed at the idle. When the car got warmed up it never dropped below 1400 rpm. It used to stay at or around 700 rpm. Could the polisher have turned the idle screw?...That is not a pain to change is it? The other thing that happened was when i pulled into the garage after the run I let it sit for a sec (still idling high)...I went to turn the lights off and the idle started sort of surging the engine. The A:F gauge was going very lean than not then very lean and off and on. When i would turn the lights back on it would go away. I tried it about three or four times and each time was the same. It was very strange...

Any comments/help would be greatly appreciated. I am attending a mountain drive this weekend and would really like to have the car 100% if at all possible.

Thanks,,
Jon

Does the high idle fluctuate when you are not in gear and without electrical load on the car?

If so, I would suspect that there is a UIM gasket leak. The engine idle fluctuates in a rhythem that goes vrooom, vroom, vrooom right? If so, that's probably why.

Before pulling the UIM to replace the gasket, try loosen/tighten the bolts holding the UIM to the engine a little to see if that helps. Try the same for the bolt holding the throttle cable to the UIM also. Sometimes less serious leak are due to this.

Also check as much of the vac hoses under the UIM to ensure they're all connected properly. If the high idle is stable, your idle probably just needs to be adjusted.

When it first starting and was sitting idling I didn't have a problem. Yes the engine rhythem was similar to that.

We then went for a drive but I had the lights on the whole time and when coming to a stop it didn't have any crazy idle problems except for the fact that it was high. After the run, I shut the lights off and left the car idling and that is when it started doing what your describing.

What effect would shutting the lights off have to do with the UIM being too loose/tight. BTW, we torqued the bolts to what the manual specified. Also the UIM gasket was new.

The light or any other load such as AC will force the idle to be higher, thus prevents the idle from fluctuating most of the time.

It sounds like an intake leak. I am just not sure WHERE since you said that you tightened the bolts to spec and the gasket is new. All I can say is try loosen some bolts and see what happends. If you are sure the gasket is seated correctly and debris free when you installed it, I would look at possibly some of the hoses and solenoids under the UIM.

Also, are you absolutely sure the idle wasn't messed up before your UIM polish? The LIM is also prone to intake leak as the stock paper gasket leaks. I had mine UIM gasket replaced and the idle is fine now. That's lots of labor though as the turbos have to come off to get to the LIM.

I concur, gasket leak.

It might be the UIM. Should I loosen it and see if it gets worse?

The idle, before taking the thing apart was fine. We took it apart to change some solenoids to fix a boost issue. During that time I had the parts polished. I think we got all the parts on the way they came off but I would have to recheck to make absolutely sure. I really don't want to take the manifold off again to get to the stuff underneath if I can help it.

I really don't think the polisher would have messed with my idle screws settings but you never know...if that was the problem, which screw would need to be adjusted? I know there are many in terms of idle related.

Would it only be the UIM gasket or could it be the TB and/or elbow gasket too. The UIM gasket is brand new with this install. The TB gasket is not that old either. They are both metal gaskets. I have the o-ring new for the elbow but it is not on the car right now.

Thanks

help

No, try turning the bolts 1/8 of a turn to see if the idle smoothes out, especially make sure the throttle cable bolt isn't too tight and the cable isn't too tight.

Try spraying some carb cleaner on the gaskets to see if the RPM picks up a little. Sometimes it's hard to tell though bc your engine is already high and therfore loud.