Idle Problems on '86
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Idle Problems on '86
A friend of mine was having problems with his idle. The car will start, but then intermittantly stall, if you don't feather the gas pedal.
His Snap-On scanner showed no trouble codes, neither did my diacom. All sensors checked out okay, TPS, EGR, MAF, etc. I even went as far as connecting the '86 ECM that I'm putting into my '85 racecar that I'm building to see if it made any difference, bit it didn't. The fuel pressure is fine, the air filter is clean and the timing is okay. The car is stock with an auto trans.
I suggested we should now call a priest. Any other ideas?
His Snap-On scanner showed no trouble codes, neither did my diacom. All sensors checked out okay, TPS, EGR, MAF, etc. I even went as far as connecting the '86 ECM that I'm putting into my '85 racecar that I'm building to see if it made any difference, bit it didn't. The fuel pressure is fine, the air filter is clean and the timing is okay. The car is stock with an auto trans.
I suggested we should now call a priest. Any other ideas?
Le Mans Master
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From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Idle Problems on '86 (stuntman)
What was the IAC doing? How many counts? What was desired idle vs. actual idle? Could be a million things!
I would pull the TB and clean it. Make sure you remove the covers and clean the IAC passages. IAC may need replacement, there are mixed results on this board from just cleaning.
If you think you should do the TB cleaning, then make sure you go to the tech tips section on this forum and do the minimum idle air and TPS adjustment!
Good Luck,
Pete
I would pull the TB and clean it. Make sure you remove the covers and clean the IAC passages. IAC may need replacement, there are mixed results on this board from just cleaning.
If you think you should do the TB cleaning, then make sure you go to the tech tips section on this forum and do the minimum idle air and TPS adjustment!
Good Luck,
Pete
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Re: Idle Problems on '86 (PeteL)
you must do everything Pete said, are you not getting any codes from the computer?
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Re: Idle Problems on '86 (PeteL)
Hi Pete,
I left my laptop and software over at his place, and I don't recall any specific readings off the top of my head, including the Idle Air Control. I do know however, that tere were no vacuum problems present (that we could find).
As far as the "desired vs. actual idle"...We desired idle, but actual idle didn't happen!! (Yes, that was intended humor)
This IS one of those "could be a million things", but I was trying to start by hitting the most logical ones first. Didn't try cleaning the TB, but maybe that'll be next. I'll be back over Monday, and let you know if it works. If it does, then give yourself $20 dollars.
Thanks a lot,
Joe
I left my laptop and software over at his place, and I don't recall any specific readings off the top of my head, including the Idle Air Control. I do know however, that tere were no vacuum problems present (that we could find).
As far as the "desired vs. actual idle"...We desired idle, but actual idle didn't happen!! (Yes, that was intended humor)
This IS one of those "could be a million things", but I was trying to start by hitting the most logical ones first. Didn't try cleaning the TB, but maybe that'll be next. I'll be back over Monday, and let you know if it works. If it does, then give yourself $20 dollars.
Thanks a lot,
Joe
Burning Brakes
Joined: Dec 1999
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Re: Idle Problems on '86 (stuntman)
Lets start from the begining: What was he doing to the car when this started. Was he working on the car? if so, what exactly was he doing? Or did this start out of the blue?
Instructor
Joined: Nov 2001
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From: Olympia Wa
Re: Idle Problems on '86 (stuntman)
I started having intermittet problems with cold start hard start. when cold it would start and imedatly stall.... the problem turned out to be the EGR valve stuck open....... pulled the EGR valve and cleaned and tested it reinstalled it and no more cold start problems.........
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Re: Idle Problems on '86 (Cruzin I-5)
The problem started slowly. Apparently, it would doit, then correct itself. It's still intermittant, but more often it won't idle, than the times it will.
As far as the EGR goes, we tested it AND replaced it with one that we knew worked fine. The computer (diacom and Snap-On scanner) show NO trouble codes. Again, I don't recall the EGR duty cycle (30%?), but everything seemed fine when scanned.
Anyway, thanks for all the input guys,
Joe
As far as the EGR goes, we tested it AND replaced it with one that we knew worked fine. The computer (diacom and Snap-On scanner) show NO trouble codes. Again, I don't recall the EGR duty cycle (30%?), but everything seemed fine when scanned.
Anyway, thanks for all the input guys,
Joe
Burning Brakes
Joined: Feb 2001
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From: Wichita, Ks, USA
Re: Idle Problems on '86 (stuntman)
Mins did this from time to time-- then very often and now is running strong again. The 1st time i installed the plenum gaskets on the wrong sides making the idle air circut be blocked 
. Fixed that. did it some more-- changed fuel filter-- fixed. started doing it again so i replaced the filter thinking maybe when i ran it down low it sucked up some garbage-- filter clean-- still did it. It fixed itself again the day i went to check the fuel pressure which was fine. We were thinking it may be the EGR valve. :confused:
. Fixed that. did it some more-- changed fuel filter-- fixed. started doing it again so i replaced the filter thinking maybe when i ran it down low it sucked up some garbage-- filter clean-- still did it. It fixed itself again the day i went to check the fuel pressure which was fine. We were thinking it may be the EGR valve. :confused:
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From: Guyton GA
Re: Idle Problems on '86 (stuntman)
If it won't even throttle around 800-1000 rpm and stalls abruptly then it is probably the MAF. Then unplug the elec connector to the MAF and see if that is better(limp home mode). Otherwise I would say it is the IAC valve.
