Help, high idle!

[tsi1991awd]

Its me again...I just bought a 1991 Talon TSI AWD on Friday night. Everything was good with it. The idle was fine after driving and everything. It was around 800 or so. We'll yesterday it had a high idle even after it warmed up. And today after letting it fully warm up and driving and whatnot, the idle will still be high. At about 1200rpm. I swear when it was at idle on Friday night, the boost gauge was at the bottom. This is the stock boost gauge.

But now, when its at idle, it has about half of the vacuum portion...there is a mark for -7 and the needle is between the bottom and -7...when I turn the car off, the gauge is still at that point. If I only turn the key to accessory, the gauge will be at the bottom of the boost portion...like 0psi. Then I turn the ignition off and it goes back to that one spot I mentioned in the vacuum. So I am not sure that it was at the bottom on friday night, since it seems its normal to be at that point now.

Also, my gas pedal feels like it is "stuck" when I first try to get going from a stop. Kind of sticks and then I push it a bit hard and it "breaks free"...and once I'm driving in a gear, it'll push like normal. Say 2nd or 3rd gear. Etc. And I think it seems like it sticks a bit when I shift into another gear.

Any idea what would cause the high idle and the gas pedal to do that? As I said, it was fine friday night and these things started happening yesterday. Any help would be much appreciated. Thanks.

 

[eeeewidner]

Check your high idle switch. Loosen the jam nut under it and back out the switch a few turns.. Or even turn it in and reset your base idle...

As of your boost gauge. Buy a gauge. They aren't that expensive and good insurance.. My stock gauge does the same thing. Yet my Autometer gauge reads completely different... Check your throttle cable for kinks and what not starting with the hold down clamp on the intake manifold. If ok, check your throttle. Again back to the fast idle switch....

 

[tsi1991awd]

Where is the high idle switch? Sorry, haven't gotten a manual yet since I just got the car.

 

[Jeff99GS]

Turn down the BISS air screw on the throttle body. Its a philips head screw. You will need to turn it clockwise while the car is running.

It is normal for the car to idle up to 1200-1500 rpm when it is cold. when the car warms up it should idle aroung 700-800 rpm. and 900-1000 rpm with the A/C on.

 

[tsi1991awd]

Would it just come out of spec like that on its own? Should I let the car warm up then do the screw? Because it idles higher when cold, maybe 1800 to 2000 then goes down to about 1200 when warm. So....could be that screw, but it just did it on its own??

 

[eeeewidner]

Turn down the BISS air screw on the throttle body. Its a philips head screw. You will need to turn it clockwise while the car is running.

It is normal for the car to idle up to 1200-1500 rpm when it is cold. when the car warms up it should idle aroung 700-800 rpm. and 900-1000 rpm with the A/C on.

Very true....My car does the same thing, i.e. erratic idle, it only does it if I run the car hard, but it always goes back to normal idle after a few minutes...

 

[PIMking]

Heck my car idles at 2k for 10 seconds or so then drops down to 800 or so. but it idles while cold at 3k.

 

[tsi1991awd]

Well, when I turn the A/C on and the fan kicks on, it drops the idle down to a bit below 1,000. Then when I turn everything off it'll go up to 1,500 for a couple seconds then sit around 1,200. I'll try that screw and see what happens...

 

[ClipseAPG]

I have an erratic idle and from the looks of it my culprit is the TPS (throttle position sensor) so try comparing your exact symptoms to those of faulty TPS'. Anyone else think that could be his problem?

 

[tsi1991awd]

Thanks for all of your help guys, I went out and started the car, it was still warm from driving today but I let it warm up about 5 minutes, and I turned the idle screw on the throttle body...the phillips screw. Got the idle down to 800...revved it, came down to 1,000 for a couple seconds then went down to 800. Went out for a short drive, pulled it in 2nd and 3rd gear for a few seconds. Then came back and parked....still idled normal. I'm not sure how that got out of adjustment, but it is working just fine now. Hopefully it stays that way!

 

[SnowBird]

Thanks for all of your help guys, I went out and started the car, it was still warm from driving today but I let it warm up about 5 minutes, and I turned the idle screw on the throttle body...the phillips screw. Got the idle down to 800...revved it, came down to 1,000 for a couple seconds then went down to 800. Went out for a short drive, pulled it in 2nd and 3rd gear for a few seconds. Then came back and parked....still idled normal. I'm not sure how that got out of adjustment, but it is working just fine now. Hopefully it stays that way!

Buy a manual and look at how to set the idle. You have to ground the timing adjustment connector on the firewall, and ground a pin in a connector down by the fuse box in the car; and then adjust the phillips BISS screw. Just turning the screw will work, but this way will be more insurance.

 

[tsi1991awd]

Buy a manual and look at how to set the idle. You have to ground the timing adjustment connector on the firewall, and ground a pin in a connector down by the fuse box in the car; and then adjust the phillips BISS screw. Just turning the screw will work, but this way will be more insurance.

I did buy the Haynes manual earlier and that's what I looked up on how to adjust the idle and it didn't say anything about grounding any connectors....maybe I'm missing something?? What section/page?

 

[Laysher91]

It should be under the "curb idle speed" section.

 

[tsi1991awd]

Still didn't see it...only thing I find is in chapter 4 about the idle speed screw. Went to TPS sensor in chapter 6 and it just says refer back to chapter 4 and whatnot. Maybe I'm looking in the wrong place...glossary didn't have anything about curb idle speed

 

[steve]

1G BISS Adjustment

At the bottom of the VFAQ they talk about an o-ring. Go get one. It's likely yours is hard and dried out, due for replacement.

Also check the ISC. If the coils short it will damage your ECU. The ISC is a key part of the idle circuit.

DmTaLoN's Idle Speed Control Test/Fix Page!

 

[tsi1991awd]

I checked out the biss adjustment...looks good. I only have one question...before I do anything, do I remove that adjustment screw, put the new o ring in, and then put the adjustment screw back in, THEN start the car and do the adjustment?

Also, I do not have that cap to go over the screw. Do I need one or is it OK to do without?

One more thing...it says to use a #5 O-Ring, and lists the dimensions as 3/8 x 1/4 x 1/16. I looked at the Schucks website, and #5 http://www.partsamerica.com/ProductDetail.aspx?MfrCode=DOR&MfrPartNumber=64005&CategoryCode=3127 is listed as 3/32" I.D., 7/32" O.D., 1/16 Thick....but a #10 is listed as 1/4" I.D., 3/8" O.D., 1/16" Thick....so which is it??

 

[Jeff99GS]

The O-ring is ON the biss screw itself. Turn the Biss counter clockwise till the head is sticking up a lil, then you can use a needle or pick to pull the biss out of the throttle body. Once it is out you can just pull the O-ring off and take it to Napa...they can match it up for you.

I wouldn't worry about a cap for the biss.

 

[DroopYeyeS]

Your throttle "sticking" feeling problem is more than likely the throttle plate in the throttle body. Try cleaning the TB out and adjust your throttle plate so that it doesn't close 100%.

 

[tsi1991awd]

Thanks, ill take it out and see what Napa says. As for the sticking pedal feeling, ill clean it out and see what it does. Thanks!