C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Idle Problem

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Old May 6, 2025 | 03:44 PM
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Default Idle Problem

Have a 1992 and it has an idle problem. Idled at 2k rpm. Changed IAC and it settles in at 1100 rpm after reset done, but climbs back to 1500 rpm after warmup. No vacuum leaks. I do need to replace brake booster, but I don't think that would cause the idle problem. Any help or advice is greatly appreciated.
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Old May 6, 2025 | 04:45 PM
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I do need to replace brake booster, but I don't think that would cause the idle problem?
Yes it can Big Vacuum leak, so you might want to pull and plug line for testing.

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Old May 6, 2025 | 04:51 PM
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Thanks for the info. I will pull thre lines and plug to see what it does.

Thanks again.
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Old May 6, 2025 | 06:41 PM
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Originally Posted by s carter
I do need to replace brake booster, but I don't think that would cause the idle problem?
Yes it can Big Vacuum leak, so you might want to pull and plug line for testing.
I pulled the line and boom! That is the problem. These cars are crazy, but I love them.

Thank you!!!!
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Old May 6, 2025 | 10:47 PM
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I had a similar idle situation. After many months of fretting over it, replacing the ECM fixed it.

Never mind. That's what I get for reading threads too soon after waking up. Glad you found your issue.

Last edited by 2011KLR; May 7, 2025 at 10:09 AM.
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