High idle. Driving me crazy.

magnux · Post by **magnux** » Wed Oct 11, 2006 7:18 pm

Ok, first the symptoms:

When the car is started in the mornings, it will immediately rise to about 2k. Then slowly start to fall until it stalls. I need to bump the accelerator a few times to bounce it back up until it sticks around 2k. Then it will slowly hunt down to around 1.2k and hold.

Driving around, the idle is always high. In drive, it's about 1k. After driving around, if I put it in park or neutral it goes to 1.5k or so and holds.

Not sure if it's related (although it probably is), but sometimes when slightly backing off on a spirited acceleration, the car will hesitate almost as if it's cutting fuel for a split second, but then resume with no problem.

What I've done so far:

Replaced IAC.
Reset ECU in hopes of 'relearning'.
Had PCV system checked and repaired. Few cracks here and there.
Timing belt replaced.
Replaced MAF.
Replaced air filter.

The only thing that seemed to make any remote difference was replacing the MAF. Before that, it used to go as high as 3k during the 'high' idle. A small victory.

This has been happening for a few months now, and I'm stumped. Any ideas?

* Edit: During all this time, the MBC has been removed and the car has been running at stock boost. The only actual 'modification' as of current, is a Saab 900 IC. I'd love to remove it and replace it with the stock piping once again, but unfortunately I no longer have the stock pieces at my disposal as they were all cracked and battered (hence the replacement).

magnux · Post by **magnux** » Fri Oct 13, 2006 11:23 pm

Oh, and I forgot to mention. All of those RPM's listed are with the A/C on. They're even higher with it off.

Post by **Legacy777** » Mon Oct 16, 2006 6:17 pm

Does your throttle body have an adjustment screw on the top of it?

Here's some pics
http://www.main.experiencetherave.com:8 ... images/tb/

magnux · Post by **magnux** » Wed Oct 18, 2006 12:24 pm

Legacy777 wrote:Does your throttle body have an adjustment screw on the top of it?

Here's some pics
http://www.main.experiencetherave.com:8 ... images/tb/

Yes, and I've never so much as sneezed at it. :p

Post by **Legacy777** » Wed Oct 18, 2006 5:49 pm

Have you done anything to the throttle body?

Try turning the screw clockwise and see if that changes anything.

magnux · Post by **magnux** » Wed Oct 18, 2006 6:48 pm

Legacy777 wrote:Have you done anything to the throttle body?

Try turning the screw clockwise and see if that changes anything.

No, I haven't done anything to the throttle body. I thought I've read that touching the idle screw was a no-no?

IronMonkeyL255 · Post by **IronMonkeyL255** » Thu Oct 19, 2006 1:27 am

Sometimes it can work its way out over time.

Happened to me. I just turned it in until it idled where I wanted it, then Loc-tited the bastard.

Post by **Legacy777** » Thu Oct 19, 2006 8:43 pm

magnux wrote:
Legacy777 wrote:Have you done anything to the throttle body?

Try turning the screw clockwise and see if that changes anything.
No, I haven't done anything to the throttle body. I thought I've read that touching the idle screw was a no-no?

The idle stop screw and the needle valve screw on the top of the throttle body are two different things. You should not touch the idle stop screw. In your situation, adjusting the needle valve screw shouldn't hurt anything.

Bimota_sb6r · Post by **Bimota_sb6r** » Sun Dec 24, 2006 6:10 am

i have a 91 ss auto trans. and i have the exact same symptoms. i cleaned the idle air vavle(its was sticking a little so i used seafoam)then i replaced the pvc vavle from the DEALER!(recommended) then i replaced every vaccum hose i could reach..... and still nothing!!!! finaly i broke down and replaced the throttle body gasket and intake manifold gasket(while i had it off i painted it red:P) this helped dramatically it no longer died and had near perfect -vaccum pressure(-20psi)but it still idles high sometimes and when it idles down it only drops to 500rpm and purrs. its alot of work but the car is much less annoying and looks awsome with the painted intake. also every time i changed something i unhooked the battery for 15 mins and pressed on the brakes. i hope this helps

NuwanD · Post by **NuwanD** » Sun Dec 24, 2006 6:17 pm

Seems as though the engine is behaving as if it were cold... possibly the coolant temp sensor?

Bimota_sb6r · Post by **Bimota_sb6r** » Thu Dec 28, 2006 4:18 am

would that effect the high idle or the stalling?

Post by **Legacy777** » Thu Dec 28, 2006 5:17 pm

Yes it could.

redlineracer · Post by **redlineracer** » Thu Jan 04, 2007 10:57 pm

I would check the condition of your TPS pigtail connector where it clips into the TPS and also while your at it I would look t the entire wiring to see if it has any sspots where metal wire is exposed. If there is, then tape it up cause it might be grounding the signal to another metal part of the car. Re-check the connection of TPS pigtail connector see if it cracked, broken or something is out of place. If its all there then I would have the TPS itself checked out. When I had a high idle problem I changed out my TPS pigtail cause it was broken at the clip and one of the wires wasnt sitting right so I finally changed it out and now when I start the car, it will idle for 1-2 minutes before then drop to normal operating RPMs of 750-850 rpms. It made a huge difference. While ur fiddling with the throttle body I'd clean out ur TB out with air intake cleaner, and you should notice a difference. Dont try to attempt to move the TPS itself unless u know what ur doing!

onur · Post by **onur** » Sun Aug 05, 2007 4:11 am

it may be the neutral switch. My car did it when i did AT to MT swap.

ThreeEyedBandit · Post by **ThreeEyedBandit** » Mon Aug 06, 2007 7:27 pm

I had the same problem when I made my turbo harness, and it ended up being a broken idle switch wire between the ECU and TPS. I believe it is a solid brown wire.

Matt

Ej22TIM · Post by **Ej22TIM** » Mon Oct 22, 2007 5:13 pm

i had this same problem for as long as i had my car. at some points i would be idling at 3100rpm especially after hard acceleration.

i put a wrx intercooler on my car with a jimmy rigged piece if rubber for a seal between the cooler and the throttle body, this instantly ripped when i put it on, which i didnt know. another thing that was causing my idle to be high was my bov was literally sitting on my throttle body pushing my idle to "making me angry" heights.
so if you are running a top mount check your seals, it could be a post maf air leak (i was still running -20psi with the leak) or it may be something as simple as your throttle body is being blocked from closing properly.

BB · Post by BB » Sat Nov 17, 2007 9:34 am

Try reseting the TPS according to a haynes, or fsm. You should never change the throttle set screw unless somthing is wrong.

I cant remember the process but it involves some feeler gauges and a voltmeter.

BB

subytech · Post by **subytech** » Thu Nov 22, 2007 4:35 am

Bump on all the TPS hints, adjusting the TPS i think would be hard unless you have a scanner than can show you the TPS value but if theres a procedure without the scanner go for it, also spray some brake clean or carb clean or anything presurised and cumbustable around all the gaskets and vacuum lines, if the engine speed changes you have a vacuum leak you need to track down. good luck

BB · Post by BB » Thu Nov 22, 2007 7:23 am

'cmon who's gonna post up a scan of the haynes manual tps setup? I remember doing it on my NA motor to change RPM restore thresholds... you know when the revs "hang" inbetween gears? you can change that according to the tps setup.

Feeler gauges and a volt meter... I remember that much

BB

tahiti350 · Post by **tahiti350** » Fri Nov 23, 2007 12:30 am

My Wagon just saarted doing this, was parked for a couple of months due to "severe cosmetic damage" (now repaired), and not it's idling around 1000-1100 in gear, and 1500 in neutral, A/C off.

It's also been hard to start (always). Have to hold the throttle up a bit when cranking or it will start and die. Would be nice to be able to just trun the key and have it run....

BB · Post by BB » Fri Nov 23, 2007 8:40 am

EJ22's should NEVER be hard to start. down to minus 40c... they should fire right up.

tahiti350 you may have other problems like a boost leak (aka vac leak) .

Generally non savvy mechanics screw with the TPS and eff it up.

If your car sat, and you changed nothing its unlikely that your TPS need calibration. Look for a boost leak.

BB

tahiti350 · Post by **tahiti350** » Sat Nov 24, 2007 1:41 am

cool, thanks, will check it out this weekend. I know the mileage is down a smidge too.

hardcore1 · Post by **hardcore1** » Sun Nov 25, 2007 8:53 pm

I have a 91 L sw no turbo awd MT. I have had the car for some time and know it pretty well. Spanked some corvettes at an autox once, that was fun.

Anyway, got an issue of high idle.

car is warm, decent temp outside.

Car idles at 1750+- with "THE CLUTCH OUT, NOT PRESSED whether at a stop in neutral or driving in gear"
Push the clutch in and idle goes down to 750 or so. Had the standard codes is the past 22, 35, 12-fixed the temp sensor.
Now I am getting an occasional 42. Just did a vaccuum test with carb cleaner and found the only place idle changed with spray was next to the throttle body passenger side directly below the pcv valve. I assume this is the air idle control. I believe this is the code "42" also.

Anybody have some input?

Post by **Legacy777** » Wed Nov 28, 2007 6:40 pm

Here's the scan for adjusting the TPS

http://www.main.experiencetherave.com:8 ... sting3.jpg

hard core, the idle switch, code 42 is located in the TPS. Use the instructions in the scan I just posted to adjust the Idle switch. If it can not be adjusted properly, replace the TPS.

hardcore1 · Post by **hardcore1** » Wed Nov 28, 2007 7:01 pm

Thanks I wil give that a shot. Which side of the plug does the pin count start at, or is it labeled?

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High idle. Driving me crazy.

High idle. Driving me crazy.

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