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Discussion Starter · #1 · (Edited)
Hey guys I just got up here to big bear, ca... Had an overheating issue when climbing the mountain. For your info the climb is 3000ft to 7000ft in about ten to fifteen mins.The temp climbed really high really fast. I pulled over three different times to let it cool down... At one point it got to 280. I couldn't stop because of grade I was on I had to wait for a turn out. Anyways I made it up with no failures i.e head gasket etc etc.

But now I have one issue... Towards the top of the climb I was having stalling issues whenever I would let my foot off the gas. Now no matter what I can't start the car unless given a tiny amount of throttle.. And it will also stall while driving when not given throttle every time. What do you guys think could have happened in-between the overheating and the climb up the mountain?

For you info:
Codes 14,23,36,43

Before this she was running like a champ.

1986 auto.
 

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Discussion Starter · #2 · (Edited)
Most of those codes were thrown because if the overheating issue and no vss when I would stall. The 36 Maf burn off I'm still looking into... Cleaned Maf with Maf cleaner and didn't see any changes. Could be idle be off somehow? I do not know of the mountain climb somehow threw it off? I've replaced pretty much every sensor since Ive bought the vette back in Jan.
 

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I don't know could have something to do with how thin the air is and opening the throttle blade helped get air into there. Are you still at that altitude?
 

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Discussion Starter · #4 ·
Ya I'll be here for 12 days... My hometown is around 2300ft. I also noticed the coolant temp varys from 218 to 245. I'm not used to 245... Normally the car starts to cool around 235... But now it goes to 245 before cooling.
 

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Discussion Starter · #6 ·
I hope so! I'm going to take some photos of it by the lake... Haven't showed it off yet.;)
 

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Discussion Starter · #7 ·
So can the thin air mess with the cooling system as well?
 

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Discussion Starter · #8 ·
Hey can a blown head gasket cause a no idle condition? I am starting to flip on the overheating I had going up the hill. Drove It around the village yesterday and the coolin system was working perfect... 198 to 220 range. It just won't hold the idle or completely dies while driving and I take foot off the pedal.

I have the iron heads f.y.i
I am not seeing oil in the coolant or coolant in the oil.
No white smoke or weird smells.
The only thing I am worried about is a possible compression issue at idle. But hopefully the higher altitude is just what's causing it...
 

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Sounds like the idle air controll (IAC) which opens when the car is at idle to let air in. They can get carbon buildup and not be opening properly.
 

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Discussion Starter · #10 ·
I replaced the iac about 3 months ago... I wonder if it got gummed up already.... I'll have to check.
 

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Just a chime in on the water in oil part, was wondering if you realized that normally you won't actually see the coolant in it, your oil level will "mysteriously" rise, such as above full mark. I'd guess that it is a gummed up or defective IAC though.

~wd-40:buhbye:
 

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Discussion Starter · #12 ·
Hmm didn't know that.. I thought it looked like chocolate milk shake when water is in oil? And hello again wd40 lol.

Come to the of it, I was having intermittent stalling and starting issues back at home before this trip to big bear... Sometimes the vette wouldn't start with out the pedal being pushed on... And sometimes the car would start up just fine without having use the pedal.

But never would the car cut out on me while in motion when foot taken off pedal.. Usually only at stop lights..

I must not have set the iac properly...
 

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I vote AC too, mine was acting up the other day and I took the old one out to clean.
The pintle was so stuck, I didn´t think it would loosen up again.
Well after a night in WD40 it loosened up, checked the resistance wich was ok, put it back in, started, died immediately.
Disconnected the connector, connected a new one to it, laid it on the engine to see if it got a signal from the ECM... yes it moved.
So I put the new one in, car has started ever since.
Another thing that could be going on is the CTS.
If you have an FSM, there should be a list where you can compare resistance values and temps, to see if it is still in spec.
 

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I must not have set the iac properly...
Do you have it chipped? If so, I would set the IAC by using IAC counts. All systems off and engine running. 20 counts. That gives the IAC room to move should it determine it needs to. That is also assuming your timing is spot on. Also assuming you have cleaned the TB and removed the IAC housing for cleaning.
 

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Discussion Starter · #15 ·
I'm not chipped, I also cleaned the tb and iac housing well when I replaced the iac. How do I do iac counts? Do you mean to unplug it or?

Also the timing is right on and all my ign is good.
 

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I'm not chipped, I also cleaned the tb and iac housing well when I replaced the iac. How do I do iac counts? Do you mean to unplug it or?

Also the timing is right on and all my ign is good.
Here is what I do. The stock way of doing it depends on stock everything. As such, you set the min idle speed and you can go from there. They way I set it, the idle speed that the ECM commands doesn't matter. Run the motor till it gets into closed loop and a stable temp. Shut everything but the motor off. No lights, AC, stereo, etc, etc. Hook up scanner and go to IAC counts. Your target is about 20 counts. If you have say more than 20 counts, it means the IAC is opening up more than your 20 count target. That means the TB needs to be opened up more. Give it a twist and then rev the motor and see it settle. If it is less than target, open it up more, rev and see where it settles. Get to about 20 counts, go for a short drive and come back and verify. When that is done, check the TPS. This is done with a scanner.

Assuming your timing is on and ign stuff is good (IOW no wire leaks, plugs are fresh, cap, rotor, etc, etc), you are good to go in that dept.
 

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Here is what I do. The stock way of doing it depends on stock everything. As such, you set the min idle speed and you can go from there. They way I set it, the idle speed that the ECM commands doesn't matter. Run the motor till it gets into closed loop and a stable temp. Shut everything but the motor off. No lights, AC, stereo, etc, etc. Hook up scanner and go to IAC counts. Your target is about 20 counts. If you have say more than 20 counts, it means the IAC is opening up more than your 20 count target. That means the TB needs to be opened up more. Give it a twist and then rev the motor and see it settle. If it is less than target, open it up more, rev and see where it settles. Get to about 20 counts, go for a short drive and come back and verify. When that is done, check the TPS. This is done with a scanner.

Assuming your timing is on and ign stuff is good (IOW no wire leaks, plugs are fresh, cap, rotor, etc, etc), you are good to go in that dept.
Forgive me my ignorance, but what do you mean when you say, give it a twist?
Do you mean turn the idle screw on the back of the throttle lever...?
I can´t think of any other adjusting method... just wondering...
 

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Forgive me my ignorance, but what do you mean when you say, give it a twist?
Do you mean turn the idle screw on the back of the throttle lever...?
I can´t think of any other adjusting method... just wondering...
My bad. IAC count high, screw it in. IAC count low, screw it out. Yes that is the screw
 

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OK, I still have the seal on that one, but I never checked it that way with the scanner.
When I start mine, it revs up to almost 2000 rpm for just a second and then goes down to 1300, stays there for say 10-20 seconds and finally will go down to 1000-900.
When I start driving and come to a stop after a mile or two, it will hang arround 1100.
Later on with the engine warmed up it might go down to say 700-800 and that´s it.
Seems a tad high everywhere, but could be wrong.
Can´t find any vac. leaks though.
And just replaced the IAC with a brand new one that works, the old one was stuck and wouldn´t let the car running when just started, had to slightly open the throttle to keep it going.

BTW, it´s a 91 AT.

How´s it going for the OP?
 

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OK, I still have the seal on that one, but I never checked it that way with the scanner.
When I start mine, it revs up to almost 2000 rpm for just a second and then goes down to 1300, stays there for say 10-20 seconds and finally will go down to 1000-900.
When I start driving and come to a stop after a mile or two, it will hang arround 1100.
Later on with the engine warmed up it might go down to say 700-800 and that´s it.
Seems a tad high everywhere, but could be wrong.
Can´t find any vac. leaks though.
And just replaced the IAC with a brand new one that works, the old one was stuck and wouldn´t let the car running when just started, had to slightly open the throttle to keep it going.

BTW, it´s a 91 AT.

How´s it going for the OP?
When you replaced the IAC with a new one, did you take the TB out, clean out the passages and remove the IAC housing and clean that too?

It does seem high even for my car which has a slightly different cam. You are SURE there are no vacuum leaks and your timing is on 6 deg?
 
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