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Real high idle, dangerous to drive, help!


PCGUY112887

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Everything has been fine till this morning, I go out today and start the car and I notice it's idle is about 1300. We had a big temp change so I was like whatever it'll get used to the new temp.

 

I drive down the road and notice my idle is now about 1500. This is a rock solid idle, no jumping around, no SES light. I'm like humm...

 

I start to get close to school and now I am at about 2000-2500rpm idle. This is when it gets hairy, every time I stop it's a battle between the brakes and the engine. It's like I'm brake torquing at every stop, and constantly riding my brakes since the car will just go faster and faster and shift and everything.

 

Got into the parking lot, slam my car into the cement parking stop since it's basically uncontrollable now (I let off the brake a bit and I fly forwards).

 

I didn't look at it, I come out after school and start it, idles at about 1300, back it up, put it in drive, all is fine the whole way home.

 

Wtf happened? IAC gummed up? I thought maybe a vac leak but it's fine now, and the idle was steady, rock solid didn't jump around at all.

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I know this is from a TGP, but reading your post made me search to a time I read this.

 

now the update:

earlier i took everything back apart just for shits and giggles. either that or it would've just sit. well again everything was fine, o-rings, injectors seated properly. however the only thing i noticed was the pvc hose end where it actually connects to the pcv was connected, but slightly crooked. put everyting back together and walla.

 

NEW PROB:

now the car ran rough for a litttle while and eventually leveled off which is expected, but it' still is around 1500.

 

So check the PCV hose I guess. Vacuum leaks can do weird things

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My throttle cable is actually brand new, shop made the cable start to fray when they pulled stuff to do my LIM so I made them replace it.

 

TB shouldn't be sticking, cleaned it a few months ago but I can try again.

 

My PCV on the other hand has been cracked in half and is being held together with a rubber thing and some tape. Has been like that for a long time though.

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i am shocked today. my 94 cutty has done the same exact thing today. I came out this morning to it idleing at 2000 rpm and a ses light, (which has never come on) so i fought it all the way to work and back as it became almost uncontrollable. Update. i am now unable to drive the car because it will not go under 2500 rpm and i am very afraid to take it out of park. even if i push the brake pedal it revs even higher. :willynilly:

Recently i cleaned the TB changed the TPS and the IAC and the pcv valve. this came with absolutely no warning of anything. This is urgent now because i cannot drive it. I have no idea what it could be. I cant even find a vacumn leak :mad:

 

[attachment deleted by admin] Removed to free up storage space.

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FIxed lolit was the CTS (coolant temp sensor) went bad and told the engine it was like 40 below and full throttle to compensate. 12 dollars and it runs like brand new :mrgreen:

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Because a cold vs hot motor the timing is different thats why you where having a prob the same thing was happening to me because we broke it when i was changing my LIM

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not really sfe to drive. I had a friend with a 9 bonne and it had the same issue. it was quite dangerous actually. CHECK THE TPS (throttle positioning sensor :mrgreen:)

My high idle started again all of a sudden, so I got it home and put it on the scanner. Everything seems fine, aside from the fact that when I'm not touching it the computer shows the throttle pos at 1.57%.

 

I checked the TB and it's physically closed, but it thinks it's open. I know for a fact that it reads 0 at idle when it's working since I scanned before.

 

Did I find my problem? It seems to do this on and off...

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Hmmm,

 

 

1. Did you watch the scanner, while trying to physically close the throttle?

2. Did you disconnect all the cables from the linkage first?

3. Did you rev it while scanning, and if so, did it always return to 1.57%?

4. Did you check the TPS mounting screws for tightness?

5. Did you check and see if the linkage is resting on the "stop"?

 

 

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Hmmm,

 

 

1. Did you watch the scanner, while trying to physically close the throttle?

2. Did you disconnect all the cables from the linkage first?

3. Did you rev it while scanning, and if so, did it always return to 1.57%?

4. Did you check the TPS mounting screws for tightness?

5. Did you check and see if the linkage is resting on the "stop"?

 

 

 

1-2-4 no, 3-5 yes.

 

I'll try the others, if it seems to be the sensor it's self then i'll swap er out.

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How does this trouble end? Did you find the culprit? My cutty is idling high also. It does seem to be temperature sensitive, but, that doesn't leave out the air plenum and intake, as they could seal more as they expand with heat. Where is the coolant temp sensor, is it just behind the thermostat housing, a bad spot of course? This whole engine is nothing but bad spots for things to be worked on. I hope when Oldsmobile was shut down, the engineers on this engine didn't move to Buick. :evil:

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How does this trouble end? Did you find the culprit? My cutty is idling high also. It does seem to be temperature sensitive, but, that doesn't leave out the air plenum and intake, as they could seal more as they expand with heat. Where is the coolant temp sensor, is it just behind the thermostat housing, a bad spot of course? This whole engine is nothing but bad spots for things to be worked on. I hope when Oldsmobile was shut down, the engineers on this engine didn't move to Buick. :evil:

um the engines changed over the years what year is your cutlass even?

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I haven't been able to get it to idle high again to test the things I said I was going to test earlier.

 

I was waiting to see if it changed when it was wet out since it seemed to happen twice when it was raining. Nothin there, it was fine in the rain.

 

Can the TPS start to go bad but not be fully bad yet? I plan on replacing it but I was just tryin to be sure that was it before I went and spent the money to do it.

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Well just yesterday I had the problem again while going to school. I pulled over, turned the car off then back on, went away.

 

Later on I went to my friends house and started my car, got a SES. I scanned it, low voltage from the TPS.

 

Replaced the TPS. Now the car is happy :mrgreen:

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Well wtf now, noticed a high idle again today and it spit another code, once again low voltage on TPS circuit... even after I replaced the TPS.

 

wtf? wiring in the harness going bad?

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CTS?

 

It seems weird that I would get a bad TPS and it act the exact same way again.

I am not extremely up on the GM stuff, because I have spent years working on Fords, but none the less, I know that if you are working on a car of any kind, you have to bleed on it in order for it to work right. Did you cut yourself and give the car some blood? If not, you didn't fix it. :lol:

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I blame all of you becasue you are all talking about:

 

My 94 is doing it too.. I know when all warmed up, it runs at 500-800 RPM.. At a stop in gear, foot on brake, it idles at 1500, sometimes 2k.. I THINK I can hear a vacuum leak, but I cannot confirm this.. What are some areas to look for vacuum leaks? It sound prominent from the driver's side of the engine bay.. I can't pinpoint it though..

 

..I also know I need a new EGR, but I doubt that would be doing this.. I am leaning toward the TB being sticky because if I rev it with my hand at the TB, it seems to settle down..

 

What are you guys doing t clean the TB? I'm certain it could be the problem.. I am going to look into it mlore as soon as I can, because I need this fixed soon.. I'll probably run and grab a CTS as well since I will have it all apart to change the TStat.. How much is a set of UIM and LIM gaskets? I'll probably go get a set of 3400 intakes also.. I THINK I get holiday pay tomorrow so thats like 80 bucks.. Goin to the Junkyard on that next time it is warm enough to do so.. (OBD2 harnesses for the Lumina, taller shifter for the cutty, 3400 intakes..)

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An EGR may do it...

 

For a sticky TB, go to walmart or wherever and pickup some Throttle Body Cleaner, and just spray everything down (with engine off) on the inside of the plate, it will take a bit... wipe it up with a rag.

 

May have to crank a few times to start after that.

 

I went up to the mechanics where he was fairly confused at what is causing it. He got out a very nice snap-on scan tool to check things out. He could adjust the TPS and EGR by hand (via the machine) to change how it ran, however when he tried to control the IAC it did nothing, as if it was stuck.

 

I replaced the IAC, haven't had the problem since but that doesn't mean anything yet.

 

I'll update in a week or 2 if the issue comes back.

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