Can a bad IAC cause a misfire while driving and at idle?
06-16-2010, 09:53 PM
#11
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I cleared the codes and ran some injector cleaner through it. Since clearing the codes I have put around 200 miles on it, and same deal. I took it to a local shop today and the mechanic said he tested the coils and injectors and cannot find the issue. I am beginning to lean toward cracked/leaking manifold or 02 sensors at this point. Gonna look into it further tomorrow and post back. Thanks again!
06-18-2010, 06:48 AM
#12
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Okay, so I stumbled across something interesting. The car only misses when its in closed loop. When its cold, it runs fine. I am gonna try unplugging the 02 sensors and see if it runs smoothly. Can I swap the rear 02's to the front to test as well?
06-22-2010, 11:25 AM
#13
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And now I take that back. For the last 2 days when I start the car in the morning and put it in reverse, it is surging BAD. It stops after a few seconds. I am seriously thinking of trading it in now, which is unfortunate. No one can figure this out including Ford.
06-22-2010, 12:30 PM
#14
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Location: Saint Augustine, FL
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Ford can figure out the problem--you just need to find a dealer with a good diagnostician who knows his way around the Integrated Diagnostic System (IDS).
Have you replaced the IAC yet? Cleaning is at best a temporary fix, and one that is not possible according to Ford...
Have you replaced the IAC yet? Cleaning is at best a temporary fix, and one that is not possible according to Ford...
Originally Posted by Ford shop manual
Note: The IAC Valve Assembly is NOT ADJUSTABLE and CANNOT BE CLEANED.
06-22-2010, 12:36 PM
#15
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I cleaned the IAC, but I have not replaced it. The only thing that cleaning the IAC seemed to do was cause a high pitched howl in the intake for about 10 minutes at idle. I am going to look around for other Ford shops and see what they might say about it. This is just so frustrating!
06-22-2010, 01:08 PM
#16
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hello friend, I see you have just about replaced everything but the plug boots, I had a problem with my car jerking while speeding up in 4th or 5th gear, replacing the boots can get expensive but auto zone has them for about $7 ea. lifetime warranty, if it don't work just return your old ones and get your money back. good luck, hope you keep your car.
06-22-2010, 01:31 PM
#18
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Once again from the shop manual--the surging in reverse reported by the OP could very well be a sticking/sluggish IAC.
OP--if the IAC is honking/howling at idle then it is almost certain that it is worn, which can create all sorts of issues.
Here's what I found when I bisected mine--I replaced it because of surging and a honking noise when cold.
IMHO cleaning one is a stone-cold waste of time, energy, and solvent...
The PCM uses the IAC valve assembly to control:
- No touch start
- Cold engine fast idle for rapid warm-up
- Idle (corrects for engine load)
- Stumble or stalling on deceleration (provides a dashpot function)
- Over-temperature idle boost.
Here's what I found when I bisected mine--I replaced it because of surging and a honking noise when cold.
IMHO cleaning one is a stone-cold waste of time, energy, and solvent...
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