2005-2014 Mustangs Discussions on the latest S197 model Mustangs from Ford.

GT irregular idle

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Old Mar 2, 2010 | 09:35 AM
  #1  
ym42's Avatar
ym42
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Default GT irregular idle

I have not driven the car for about month, waiting for the snow to clear. I also took the battery out to keep it charged and ready. Last week, when I started the car I noticed that it idles unusually low, about 500RPM when the car is moving in Neutral and between 600 and 700 when standing at the traffic light. The needle also seems to move around a little randomly... Whats up with this?
Old Mar 2, 2010 | 10:14 AM
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The car needs to relearn its idle. There is a section in the owners manual regarding this and the recommended procedure to relearn.
Old Mar 2, 2010 | 10:23 AM
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THANKS!!!
Old Mar 2, 2010 | 10:34 AM
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Also, try cleaning the throttle body. My car was doing the same thing, I just got some TB cleaner from Advance, cleaned it out really well, no more idle issues. Do that in conjunction with the throttle recalibration, you'll be golden.

Eric
Old Mar 2, 2010 | 10:42 AM
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You gotta drive it more
Old Mar 2, 2010 | 06:14 PM
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+1 on both recommendations. With the battery disconnected for more than 20-30 minutes, the adaptive learning parameters are erased (which is often a GOOD thing). It takes some miles for the feature to relearn. Until then, there often is a little instability.

A dirty TB can also cause some idle problems and it's a good routine maintenance item to do on your own every so often.
Old Mar 4, 2010 | 10:01 PM
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Cant find any info on this in the owners manual... After driving for about 300 miles its still doing it: after I rev it up, the RPMs drop to <500 and then slowly go up to 800 and down to 750... Its annoying since the the power-steering does not work correctly at 450RPM and the lights go dim... BTW - how do you clean the throttle?
Old Mar 5, 2010 | 10:20 PM
  #8  
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Just to wrap this up. Took the TB off the car, cleaned, re-calibrated the throttle and the car is as good as new. Seriously it drives completely different and the problem is completely gone.
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