High Idle (2k-4k rpms)

[dynimitejack]

I have a 86.5 mkIII N/A and when I was leaving for school today the Idle was at around 2k rpm with the engine cold. Being that the supra is my only car right now I had to drive it, it went there idling at 2k the whole time then on my way back it was idling between 3.5k-4k rpm. If I force the throttle closed it idles where it is supposed to. I have not messed with the idle set screws at all I don't think it is anything mechanically wrong with the throttle.

I popped the hood and traced what vacuum lines I could see and I didn't find anything wrong. Then I tried pinching the VTV valve running the the dashpot and nothing changed.

Have any of you guys experienced a high idle like this?

 

[rumptis]

What do you mean by forcing the throttle closed?

If its sticking open that's your problem.

I should completely close.

 

[86yota]

check your TPS ,mine was bad and i was getting alot of wacking idleing.

 

[dynimitejack]

Basically If a take a pair of pliers to the throttle linkage on the throttle body I can shut the butterfly, the butterfly hardly moves when I force it, I think that it is just the brackets flexing, because there is heavy resistance to close it. I havn't adjusted anything on the car, it was running great last night and today it idles at a steady 3.5k rpm.

When I look into the throttle body it looks right where it should be (very very close to closed). There are no check engine lights

 

[dynimitejack]

check your TPS ,mine was bad and i was getting alot of wacking idleing.

I unplugged the tps while it was idling at and nothing changed. How can I check it?

 

[dumbo]

there is adjustment nuts on your throttle cable, maybe one is backing off if you can pull it shut with plyers, maybe your cruise control is messin up(but i cant really see that)

 

[dynimitejack]

I noticed that the cable shielding where the cable comes out of the cruise control canister is broken and the cable is exposed... I looked at all the possible adjustments on the throttle linkage and nothing looked out of place or loose.

I don't think it is anything mechanical because it happened so suddenly. I think that it is either a sensor or a vacuum hose broken that I couldn't see. There are not any cels so i'm leaning towards a vacuum leak. Any ideas what in the vacuum system would cause such a high idle?

 

[dumbo]

well i was looking in my manual for yah, and it sais to check your codes, ISC valve and cold start injector, i think you can find it online so i'm not gonna go word for but its a start, and i'd start with codes.

 

[dynimitejack]

well i was looking in my manual for yah, and it sais to check your codes, ISC valve and cold start injector, i think you can find it online so i'm not gonna go word for but its a start, and i'd start with codes.

That makes sense, where can I find how to check for codes and a list of possible codes?

 

[suprarx7nut]

Why the TSRM is good for that!

Go to google, type in "TSRM"

Click on the very first listing and bookmark that page!!! (or go buy a TSRM from a toyota dealer for your supra.) Code reading (diagnostics) is in the section of EFI.

Basically, you jumper terminals e1 and te1 of the diagnostic box in the engine bay, by the fuses, and then turn the key to "on" but NOT start. Lights will flash and then you can read your codes.

 

[dynimitejack]

Why the TSRM is good for that!

Go to google, type in "TSRM"

Click on the very first listing and bookmark that page!!! (or go buy a TSRM from a toyota dealer for your supra.) Code reading (diagnostics) is in the section of EFI.

Basically, you jumper terminals e1 and te1 of the diagnostic box in the engine bay, by the fuses, and then turn the key to "on" but NOT start. Lights will flash and then you can read your codes.

Ahh thank you thats exactly what I need. I've read obd1 codes before but it was on a honda and the jumper was in the passenger kick panel.

 

[Nomad707]

umm.. if you have to force your throttle close isn't that a pretty good sign your throttle is sticking for some reason? take the intake pipe off and look at the butterfly..