Issues with ls1 motor in 1984 chevy
07-08-2014, 03:54 PM
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Issues with ls1 motor in 1984 chevy I've got 1984 chevy with ls1 motor and ls6 intake. Recently having problems with it idling right. Once it warms up it idles fine and goes good down the road. I just changed the IAC valve and when it starts the rpms goes up to 2500-2800 for about 2 seconds then it idles fine. Any suggestions what the problem could be?
07-08-2014, 08:09 PM
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If there are no codes being thrown on the ECM/PCM then as previously stated it could be a small vacuum leak; try taking a propane torch and turning the gas valve on without lighting it, and then work your way around the intake manifold/throttle body exterior/any vacuum lines, and see if the RPM's rise at all. If the RPM's rise in a given spot then that that location is likely where the cause of your problem is.
07-08-2014, 09:01 PM
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It may work its self out. If you disconnected the battery to change the IAC the computer may have dropped some of it's learned info. Also if the computer was compensating for a bad valve it may have the engine control out of whack now that the new IAC is working as it should. I would drive it for a bit to see if it just goes away.
07-09-2014, 02:26 PM
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I tried to drive it with the new IAC valve but the rpms got higher as soon as I put it in drive. The new IAC valve is a little different so but the old one back in. I will look for any vacuum leaks and I will try to do a idle relearn to see if that helps.
07-09-2014, 03:43 PM
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Are you tuning the engine? Have you messed with your Intake manifold volume because of a big cam or anything?
I was having problems with an idle that would hang way up there at like 2500RPM or so and slowly drop. Then if I just tapped the throttle it would rev way up again.
You can log your IAC position, it should hover below 100 I believe, mine would max out at like 230 or whatever and stay there while the idle was high.
I made some changes to manifold volume and tuned the VE tables and it fixed the issue.
I was having problems with an idle that would hang way up there at like 2500RPM or so and slowly drop. Then if I just tapped the throttle it would rev way up again.
You can log your IAC position, it should hover below 100 I believe, mine would max out at like 230 or whatever and stay there while the idle was high.
I made some changes to manifold volume and tuned the VE tables and it fixed the issue.
