3.1L LHO V6 Setting Idle
03-21-2016, 07:12 PM
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Car: '91 Chevy Camaro RS
Engine: 3.1L LHO V6
Transmission: Borg Warner T5
Axle/Gears: GU6 3.42 Open Diff
3.1L LHO V6 Setting Idle
So, the car used to idle like ****. Fixed a rough idle. Now the lowest I could get the idle was to 900rpms (This is a reading from a aftermarket Equus tach since the stock dash tach has bad readings since it's a 91). Manual says it's supposed to idle at about 675-700rpms. What are things I can get it that low if it really is supposed to idle that low when warm?
Replaced IAC, PCV Valve, Most vac lines since they were quite old cracking everywhere, Cleaned throttle body, replaced FPR Diaphragm since it used to dump fuel into the vac lines, new spark plug wire set, ran Seafoam through the engine via Brake Booster vac line.
(May have missed a few there. Memory a little horrible atm.)
Replaced IAC, PCV Valve, Most vac lines since they were quite old cracking everywhere, Cleaned throttle body, replaced FPR Diaphragm since it used to dump fuel into the vac lines, new spark plug wire set, ran Seafoam through the engine via Brake Booster vac line.
(May have missed a few there. Memory a little horrible atm.)
03-22-2016, 11:37 AM
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Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: 3.1L LHO V6 Setting Idle
You haven't mentioned the injectors. If they are original they almost certainly need to be replaced. Then if it's still bad.....
03-22-2016, 12:05 PM
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Car: '91 Chevy Camaro RS
Engine: 3.1L LHO V6
Transmission: Borg Warner T5
Axle/Gears: GU6 3.42 Open Diff
Re: 3.1L LHO V6 Setting Idle
According to the previous owner, he replaced them with the cheapest available option from a local parts store quite some time ago. About 2-4 years ago. (Autozone or O'Reilly's)
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I just did a Minimum Air/Idle Speed set according to the tech article here of 450-500rpms with the set-timing disconnected as well as the IAC then went through the Idle Relearn process. Hovers a smooth 900-1000rpms while its warm in neutral.
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I just did a Minimum Air/Idle Speed set according to the tech article here of 450-500rpms with the set-timing disconnected as well as the IAC then went through the Idle Relearn process. Hovers a smooth 900-1000rpms while its warm in neutral.
Last edited by inkscape; 03-22-2016 at 12:11 PM.
03-23-2016, 11:04 AM
#5
Re: 3.1L LHO V6 Setting Idle
When we install IAC valves, we do not "set pintle length" the IACV is a stepper motor. The ECM sets pintle length on its own. I would never try adjusting the IAC pintle length. Just install the new valve and preform the idle learn procedure. If you don't perform the procedure, the car will just tend to idle high until the ECM learns idle on its own. I also do not activate the IAC with it on the bench. I've seen others do it and Ive seen the pintle shoot across the shop, destroying the IACV. You can test the valve installed. The best tests are done using a voltmeter or test light and a scan tool.
So, the car used to idle like ****. Fixed a rough idle. Now the lowest I could get the idle was to 900rpms (This is a reading from a aftermarket Equus tach since the stock dash tach has bad readings since it's a 91). Manual says it's supposed to idle at about 675-700rpms. What are things I can get it that low if it really is supposed to idle that low when warm?
Replaced IAC, PCV Valve, Most vac lines since they were quite old cracking everywhere, Cleaned throttle body, replaced FPR Diaphragm since it used to dump fuel into the vac lines, new spark plug wire set, ran Seafoam through the engine via Brake Booster vac line.
(May have missed a few there. Memory a little horrible atm.)
Replaced IAC, PCV Valve, Most vac lines since they were quite old cracking everywhere, Cleaned throttle body, replaced FPR Diaphragm since it used to dump fuel into the vac lines, new spark plug wire set, ran Seafoam through the engine via Brake Booster vac line.
(May have missed a few there. Memory a little horrible atm.)
Hi Inkscape , I have enclosed a quote from a guy who I believe may have an answer to your high idle . In my reading it appears that the 2.8 does not have an idle learn procedure , but that the 3.1 does need the idle learn procedure whenever the IAC has been removed .
03-23-2016, 04:00 PM
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Car: '91 Chevy Camaro RS
Engine: 3.1L LHO V6
Transmission: Borg Warner T5
Axle/Gears: GU6 3.42 Open Diff
Re: 3.1L LHO V6 Setting Idle
But the gasket between the lower plenum and block for the intake, I am unsure of.
The tach, I'm sure is probably reading much better than my stock dash tach, but again I'm still unsure if it's 100% correct or close to.
I'm not sure if it really needs to be driven for a few mins at freeway speeds though. Some things I read said it does and some said it doesn't.
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