Taurus Car Club of America : Ford Taurus Forum - View Single Post - only runs in acceleration mode
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post #9 of (permalink) Old 01-05-2019, 05:37 PM
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Join Date: Jan 2010
Location: North Canton, Ohio
Chapter: Midwest
Year: 2006
Model: Ford Taurus
Engine: 3.0L 12v Vulcan V6
Posts: 6,536
Rep Power: 65
Originally Posted by ddan View Post
Sorry, I also have an O2 sensor. (unheated, 2-wire). I believe low or no volts from the O2 make it run rich. I'm lean.

I can make it "run" (by pumping) with the IAC valve either electrically disconnected or removed and holes blocked off.

While pumping the gas it is not in idle mode so the valve can't help.

I cleaned and tested the valve anyway.

The IAC valve bypasses air around the throttle body butterfly valve to regulate idle speed. An old boss had a 1989 or close Taurus that he drove for a week with using the method you are using. We replaced the IAC valve and it fixed the issue. You can ohm out the coil/linear motor in the IAC that will tell you if it has a blown coil but that is all and won't really tell you if it is not responding right. On older Taurus it seems like the IAV is a total shut off where the newer ones seem to set a fixed idle. I have also seen this happen on a Subaru. This is my experience but maybe it's a MAP but how good is a $10 MAP.

See attached pic.

If it were a MAP why does opening up the throttle plate enables you to run the engine? Is the fixed high pressure keeping the IAC valve shut and it doesn't use engine RPMs feedback to maintain idle. I know it is used to calculate mass air flow using temps and pressure were as a MAF is a calibrated heated wire and the temp change is related to air flow.
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Last edited by Automender12345; 01-05-2019 at 06:25 PM.
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