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Down but not out

1038 Views 4 Replies 4 Participants Last post by  namooz
My build works consistently except for idle after running 70MPH for a while. Not 65, but 70MPH. She doesn't want to idle afterward for 15 seconds or so and then she's back. Engine temps are under 220 degrees @ 95 degrees F ambient or less (two up) for extended runs (oil cooler), and there's power to spare under all conditions. Even in the mountains she runs good. Even on Ethonol she runs good. Even on 87 octane she doesn't fart, and, runs good. I'm wondering.............I've tried bumping the PC idle fuel/[email protected] zeroTP-experimented a lot. Not much if any difference. Anybody want a shot at why she lowers idle after roaming @ 70MPH for a while? :coffee: Chuck
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Mine used to do the same thing. I found the IAC stepper was sticking. I sprayed some sea foam into the hole that is in the throat of the throttle body and flushed it out. Has worked great ever since. Do a search and you should find more on the sublect. BTW IAC stands for Intake Air Control.
Always first plan is to spray the intake flanges with brake cleaner and look for intake seal leaks.
Or hold your finger over the IAC feed hole and it should kill the motor. If it does not the seals are leaking!
i wouldn't hold the finger over the iac hole. i had a high idle problem while running the t-max and the pdf said to do this and did kill the motor. no intake leaks load new revised map and it won't idle, reload old map and it still won't idle, change iac unit back to racing idle. what it did was kill the iac solenoid.

Thanks all! Will try cleaning and report back.

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