2010-2014 Mustang Information on The S197 {GenII}

cold idle fluctuating

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Old Jun 6, 2014 | 06:47 PM
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cold idle fluctuating

happens on cold start just jumps up and down for a couple of secs the second i drive the car it goes away. Smooth as butter and no codes and I did an idle relearn a couple of hundreds miles ago but forgot to drive the car. Its kinda odd and if i dont touch the throttle on a cold start up and let it sit its fine. Its just when i start its and pull it out right away she doesnt like it any ideas. Bama hmmmmmmmmmmmmmmmm
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Old Jun 6, 2014 | 08:00 PM
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Normal normal normal !!!!!!!!!!!!!
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Old Jun 7, 2014 | 02:09 AM
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Originally Posted by TheReaper
Normal normal normal !!!!!!!!!!!!!
I figured so
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Old Jun 7, 2014 | 05:26 AM
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Sometime I can feel the car 'surging' in 1st or 2nd gear when the car is cold and just warming up. Get the car warmed up and you should be fine.
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Old Jun 7, 2014 | 07:15 AM
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Originally Posted by ace72ace
Sometime I can feel the car 'surging' in 1st or 2nd gear when the car is cold and just warming up. Get the car warmed up and you should be fine.
Hmmmmmmmmm
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Old Jun 7, 2014 | 10:57 AM
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Same here, I assume it's normal.
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Old Jun 7, 2014 | 11:33 AM
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Originally Posted by ace72ace
Sometime I can feel the car 'surging' in 1st or 2nd gear when the car is cold and just warming up. Get the car warmed up and you should be fine.
My car does this too.

Just took my car to the dealer to fix a rattle, fix the drivers window (rolls itself back down as it's going up sometimes), and asked them to look into fixing the warm up surge. The only thing they said they could duplicate and fix was the rattle and that took them 3 days. The window makes a tick sound while going up every time. I am assuming that is related to the times it catches and rolls itself back down but they didn't pull the panel to investigate. On the surge they said no codes, no problem.

They said the rattle was a loose RF brake backing plate. That seems to be gone.
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Old Jun 7, 2014 | 08:54 PM
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From: Southern Al
The TIVCT needs to get it's **** together, that's why it sounds so bad.

Last edited by TheReaper; Jun 8, 2014 at 10:17 AM.
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Old Jun 8, 2014 | 04:28 PM
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I was wondering about this behavior, as my car has it too. I thought it's something with electronic throttle control, but glad to hear it's pretty common. I just let it warm up a few more minutes on a cold day, and make sure to give it 1 or 2 gentle revs up to ~1500 rpm in neutral before I get going. This seems to make the driveoff more smooth.
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Old Jun 8, 2014 | 11:30 PM
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It's just the ECU learning. Every time you start the car after sitting, the weather is different and the ECU needs to set the parameters that make the car run most efficiently. You'll see it after loading a new tune as well. The first time you start the car, it may stall or run super rough for a few seconds until the ECU gets everything in order. It's nothing to worry about.
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Old Jun 8, 2014 | 11:36 PM
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MAF dirty? How many miles?
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Old Jun 9, 2014 | 08:48 AM
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Probably just due to the car being in open loop mode. It doesn't calculate the air/fuel mixture as accurately while the car is warming up and should run a bit on the rich side. http://www.thirdgen.org/open-loop-closed-loop
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Old Jun 9, 2014 | 11:44 AM
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Originally Posted by cdynaco
MAF dirty? How many miles?
It's not the MAF had two get dirty and go out on my ranger and the cel would be going off
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Old Jun 9, 2014 | 11:45 AM
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Originally Posted by spqr
Probably just due to the car being in open loop mode. It doesn't calculate the air/fuel mixture as accurately while the car is warming up and should run a bit on the rich side. http://www.thirdgen.org/open-loop-closed-loop
Sounds about right and because I'm running an off road H pipe it's very audible when the revs drop and go back up even though it's a couple hundred rpm
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