94 LT1 erratic idle
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From: Sitting in his Nowhere land Hanover Pa
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94 LT1 erratic idle
what can cause this. when I put it in neutral the engine will run smooth but while in gear it will not run smooth. I replace the MAF 2 months ago and it went away but now its back. is there anther sensor to look at.
Instructor
Joined: Sep 2009
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From: Northwest Indiana
Erratic idle can be any number of things, especially on an LT1. The most common cause though, is usually a dirty idle air controller valve. The IAC is installed on the lower, passenger side of the throttle body below the TB blades. Just carefully remove the 4-wire electrical connector that plugs into it, remove the rubber air coupler that connects the air filter box to the face of the TB, and unscrew the IAC from its housing. Clean the tip of it with a clean cloth that is sprayed with a bit of throttle body cleaner. You can also shoot a bit of TB cleaner into the IAC opening and wipe that out with a rag. Put everything back and see how she runs.
Is your problem only with idle? How does the car run under acceleration?
Is your problem only with idle? How does the car run under acceleration?
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From: Sitting in his Nowhere land Hanover Pa
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Instructor
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From: Northwest Indiana
If you're having some issues under acceleration, it might not be the IAC but I'd still go ahead and clean it. I'd also check fuel pressure and also pull a couple of plugs and see how they're looking.
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From: Sitting in his Nowhere land Hanover Pa
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I went ahead and replaced the IAC sensor it was only 15 bucks. that seemed to help the idle so now it idle smooths but it still has a stumble on acceleration. I can rev it up fine when not in gear. its when its under load it stumbles. so I am going to see if I can barrow a fuel pressure gauge and see what it reads.
Le Mans Master
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Check the ohms of the injectors with a digital volt-meter. If on or more are off compared to the others, that may be the culprit. 
Burning Brakes
Joined: Oct 2009
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From: Minneapolis MN
Heres a test to see if engine is misfiring.Have someone get in car,start it,& put it in drive.While engine is running(but running poorly like you previously stated) dissconnect each injector,one at a time until no change in idle speed or change in stumble is felt.The engine may die even with 1 injector disconnected.Restart & try again.Once you found the affected cylinder(no change in the way engine runs or any change in idle speed is felt/noticed),you can check that cylinders injector,spark plug,spark plug wire,& compression.The above test only works with engine in drive-with someone helping you.Let me/us know after you do above test
Drifting
Joined: Feb 2008
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From: Coatesville PA
Very interested in your outcome. I have the EXACT same problem. If its acting up, put it in neutral it revs a second then idles fine. But under certain levels of acceleration and if its lugging low rpms it misses. Sure hope you find your solution.
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Melting Slicks
Joined: Aug 2008
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From: Palmdale CA
I think I over greased it when I replaced the plug wires two years ago.
now there are many things that can cause a miss or hesitation, this turned out to be my problem.
Alcohol wipe and new silicone grease (lightly) cured the problem.
Last edited by desertmike1; Nov 13, 2010 at 04:49 PM.
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I talked to a friend that wrenches on cars and told me to replace the MAF. I did that a few months ago and it ran fine then it started to act up again. so I went back to were I got it and got me another one. so it now runs fine. so I am hoping this last longer then the last time
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From: Sitting in his Nowhere land Hanover Pa
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put the new rebuilt maf on the car. the car ran great for a while then right back to were it was. would the ECM be on its way out?
Racer
Joined: Nov 2002
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From: palm harbor fl
When my lt1 was not idleing good I was told to clean the iac motor,which didn't help and the problem turned out to be the tps,replaced it and all was good.Check your sensor for the 5 volts and see if its good.Good luck
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Melting Slicks
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From: Palmdale CA
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Last edited by Nowhere Man; Nov 14, 2010 at 07:43 PM.
Melting Slicks
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From: Palmdale CA
no that I have not. but like I said it seems to idle smooth now. its just now when the motor is under load while driving it wants to break up or stumble around 1200 rpm. a new rebuilt MAF fixed the problem for about 10 miles then all of a sudden it went back to they way it ran before. that part I do not understand
How many Miles on the ignition system since it was last serviced?
Re-check the connector for the MAF, there might be some corrosion, at the connectors, you really need to use a magnifire glass to get an up close look.
I actually put up with my problem for quite some time before I got it fixed. I understand the frustration!!
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From: Sitting in his Nowhere land Hanover Pa
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I replaced the opti, wires, and plugs around 20K miles ago. I have been chasing this problem for a while too. its seems every time I work at it the problem just to come back and I just have to walk away from it before I kill it
