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92 s10-high idle and low idle


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jayschevy
User

Nov 27, 2009, 3:41 PM

Post #1 of 13 (9472 views)
92 s10-high idle and low idle Sign In

i have a 1992 chevy s10 \2.8l w\256,000 mi. with a standard tranny.it idles up to 3k on my tach or down to maybe 450.sometimes it runs good.i rebuilt the tb 3.5 yrs. ago.i took it off yesterday the top part was loose.i fixed that.i cleaned the ports,and the iac.looked at the tps. checked all the vac. was fine.
i vac. tested the egr valve,put new gasket on.and it ran fine sitting there.kind of slow by tach.adjusted the idle speed and it sounded good.went to the store,hit a red light running good.took off to cross the road and it was running at 3k by tach.i have disconnected the air cleaner temp sender,not much help.pulled the hose off the map sensor and truck nearly dies.the only thing i didnt replace was the iac when i rebuilt it.i am at a loss on how to fix it.i doubt the timing chain has ever been replaced.i changed the original water pump 4 yrs. ago.i dont know where any vacuum leaks could be.maybe the iac is bad?if anyone can give me some ideas i will really appreciate it.tried to be as specific as i can w\description of problem.any questions you have i will answer. thank you.


Sidom
Veteran / Moderator
Sidom profile image

Nov 27, 2009, 7:22 PM

Post #2 of 13 (9466 views)
Re: 92 s10-high idle and low idle Sign In

I believe that is a TBI system. One check you can do that will tell you if the problem is with the IAC system or somewhere else would be to block off the air bypass port that goes to IAC. When its idling high and you block the port, if the idle drops down to base idle, somewhere around 400 rpm, then the problem is in that system. If it still idles high then the problem is somewhere else.

The port is on top the TBI unit. Whatever you use to block it off make sure it's big enough that it doesn't get sucked down the port. Personally I wouldn't use my thumb or finger but that's just me.....Wink


(This post was edited by Sidom on Nov 27, 2009, 7:23 PM)


Loren Champlain Sr
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Nov 27, 2009, 7:33 PM

Post #3 of 13 (9463 views)
Re: 92 s10-high idle and low idle Sign In

JAY; Sidom is probaby right. Sure sounds like an IAC issue. If that isn't it, make sure that the engine is reaching operating temp. 195F. (thermostat stuck open?) Also, CTS. Is it reading correctly?
Loren
SW Washington


jayschevy
User

Nov 27, 2009, 10:42 PM

Post #4 of 13 (9458 views)
Re: 92 s10-high idle and low idle Sign In

i dont know what cts is?truck was at normal operating temp. 195 deg.i will look for the port to block off in the morning.yes it is a model 220 chevy throttle body.do you mean the air cleaner temp. sensor?it could be defective. thank you for the info.


Hammer Time
Ultimate Carjunky / Moderator
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Nov 28, 2009, 6:00 AM

Post #5 of 13 (9453 views)
Re: 92 s10-high idle and low idle Sign In

"CTS" is coolant temp sensor for computer.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jayschevy
User

Nov 29, 2009, 5:17 PM

Post #6 of 13 (9438 views)
Re: 92 s10-high idle and low idle Sign In

sidom you were correct.i blocked off the iac port and drove it enough for the engine to get hot.it ran like a charm.i crammed a thick peice of rag in the port to block it.glad i can fix this problem since the tranny is about gone on my monte carlo.when it rains it pours.
thanks for all the help,this is info to keep stored for later use.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 29, 2009, 6:10 PM

Post #7 of 13 (9435 views)
Re: 92 s10-high idle and low idle Sign In

You can't leave that plugged. that was just a test. You do have to change the IAC now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Loren Champlain Sr
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Nov 29, 2009, 7:30 PM

Post #8 of 13 (9427 views)
Re: 92 s10-high idle and low idle Sign In

Jay; Sidom may be napping after his turkey dinner..LOL.
90 percent of the time, the IAC can be removed and cleaned. Very rarely does one have to be replaced. It is an electrical solenoid that opens and closes very quickly. Over time, it will get gummy and sticky and not want to close. If you can imagine, there is a pintle and seat that must be clean.
Loren
SW Washington


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 29, 2009, 7:39 PM

Post #9 of 13 (9425 views)
Re: 92 s10-high idle and low idle Sign In

I've found that the Fords clean up and improve usually but the GMs usually aren't as successful with simply cleaning them. You can't really access the part that does the binding.

Cleaning the pintle area will make it seal better but usually won't improve the binding.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 29, 2009, 7:41 PM)


Sidom
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Sidom profile image

Nov 29, 2009, 11:23 PM

Post #10 of 13 (9415 views)
Re: 92 s10-high idle and low idle Sign In

Glad to hear you got a handle on it jay. thx for posting your results.....

Loren hit the nail on the again.....Man that stuff knocks you out...
Turkey that is....


jayschevy
User

Nov 30, 2009, 4:29 PM

Post #11 of 13 (9408 views)
Re: 92 s10-high idle and low idle Sign In

i will change it friday,not driving it now.i have been dealing with this iac for 4 yrs.it used to go down when i pushed it,now it wont.every thing inside the throttle body is spic and span,just waiting for friday.thanks to all of you for the help.


jayschevy
User

Dec 6, 2009, 7:01 PM

Post #12 of 13 (9388 views)
Re: 92 s10-high idle and low idle Sign In

got the iac replaced and idle speed turned down.it runs good now.that iac was shot,couldnt get the pintle to go down at all.glad i got it fixed.because the tranny just went out on my (good eng. and tranny!) 86 monte carlo.lol.bought that car in case my truck broke down.what a joke. thanks again everyone for the help.you guys are great!!


Loren Champlain Sr
Veteran / Moderator
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Dec 6, 2009, 7:06 PM

Post #13 of 13 (9387 views)
Re: 92 s10-high idle and low idle Sign In

jay; Thanks for taking the time to let us know. Really glad that you got it fixed. Now, on to the next one. LOL. If we can be of any help, don't hesitate. Have a great week.Smile
Loren
SW Washington






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