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Old 09-10-2018, 07:41 PM
xeris xeris is offline
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Default More High Idle

Unexpected fix for a high idle with A/C on. Discovered that the ECU will raise the idle when the A/C is turned on if the alternator output voltage is low.
Checked battery voltage at rest and got 11.? volts. When running there was 13 volts. Installed a new alt and the A/C on high idle is gone.
The engine now is slow to return to proper idle speed. When shifting the RPM hangs up around 2000 or so and if I rev it when it's at proper idle the RPM jumps up. If i'm not touching the as peddle for a short time the idle slowly settles down to 1000 RPM. Funny thing if the A/C is turned on the idle drops to where it should be quickly.
I'm baffled.
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Old 09-15-2018, 02:34 PM
xeris xeris is offline
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Default Re: More High Idle

Swapped out what was a very new IAC valve with the one that was on the replacement engine (original engine had cam sync failure) that I installed a few years ago. Cured the somewhat high/hanging idle. Idles perfectly now.
The only conclusion I can come to is the cheap after market IAC valves are junk, even when compared to a IAC that has 72K miles on it.
Maybe it's just bad luck with aftermarket parts, but this is the second "new" one that has failed.
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Old 09-15-2018, 02:41 PM
Dirtman Dirtman is offline
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Default Re: More High Idle

It's not at all uncommon for aftermarket electronic parts to be D.O.A even in multiples. Always use ford or oem stuff whenever possible when dealing with electronic valves, sensors, etc. Or at least try to stick with name brands and not parts store branded crap.
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