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Irregular idle on Deceleration

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Old 03-24-2010, 01:53 PM
  #21  
simplexdesign
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Originally Posted by harraid5711
how about changing the throttle position sensor on the throttle body? I fixed an idle issue on another car by doing this. It was a pretty easy/cheap swap.


I guess I could try it. At this point I hate throwing money at stuff that I am not sure is causing the problem. I am pretty sure if it was bad the throttle body would be putting off a code

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Old 03-25-2010, 05:59 PM
  #22  
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Bump.
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Old 03-28-2010, 09:19 PM
  #23  
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You aren't the only one. Sometimes, usually when both the engine and the weather are cold, coasting clutch-in to a stop sign rpm drops to 500 or less and stalls. I don't see rpm jumping around through.

I've tried all sorts of stuff.

Car is currently getting a dyno tune for other reasons. Hope it helps. I kinda doubt it.
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Old 03-28-2010, 09:46 PM
  #24  
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Is that awesome looking hood of yours functional? The reason I asked is that back when I had my 08 V6 pony car, I installed a CDC Shaker and plumbed it in to my cold air intake. I had the same issues as you describe. I had just loaded a custom tune by Doug at Bama so I called him to discuss it. We ecided it sounded like it might be that the airflow turbulence from the air coming in from the shaker might be honking up the MAF. I fabricated an air deflector so that the air coming in did not blow directly on my filter and it cured the problem immediately. I only had the problem with it irradic idle and dieing while moving down the road, stopped I had no issues. Just an idea.
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Old 04-20-2010, 02:19 PM
  #25  
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Originally Posted by jwharton
Is that awesome looking hood of yours functional? The reason I asked is that back when I had my 08 V6 pony car, I installed a CDC Shaker and plumbed it in to my cold air intake. I had the same issues as you describe. I had just loaded a custom tune by Doug at Bama so I called him to discuss it. We ecided it sounded like it might be that the airflow turbulence from the air coming in from the shaker might be honking up the MAF. I fabricated an air deflector so that the air coming in did not blow directly on my filter and it cured the problem immediately. I only had the problem with it irradic idle and dieing while moving down the road, stopped I had no issues. Just an idea.


The Hood has been on for a few years so I doubt it would start the problem out of nowhere
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Old 04-20-2010, 02:24 PM
  #26  
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After trying everything that I mentioned above I gave in and took it to the dealership to let them figure it out. They came back with a low voltage on the TB so they recommended to replace it. Obviously I wasnt going to pay their $500+ to install one so I ordered a new take off TB from Brenspeed installed it and I am still having the problem. Any help at this point would be greatly appreciated because I am really at a loss with what is causing the problem. My next idea was the O2 Sensors but apparently ford checked them out and they were fine

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Old 04-20-2010, 02:56 PM
  #27  
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Exactly where was this strange voltage on the throttle body? I'd like to know exactly what they were measuring - a pin wire coming from the TPS? A wire going to the t-body motor or something else?
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Old 04-20-2010, 03:37 PM
  #28  
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Originally Posted by shanec
Exactly where was this strange voltage on the throttle body? I'd like to know exactly what they were measuring - a pin wire coming from the TPS? A wire going to the t-body motor or something else?


I honestly dont remember how they said they found it since while it was there they re flashed my computer after they were told not to so I had to get new tunes made and then they ran my front bumper into a curb and are repainting it next week. So at the time I took their word that it was a TB
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Old 04-20-2010, 03:56 PM
  #29  
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Originally Posted by Black_Steed
This happens to me also. When i am slowing down for a red light and i put it in nutural the RPMs will jump around with out me applying any gas.
That shouldn't be happening. A scan tool that can read fuel trims or aeroforce gauge would come in handy for diagnosis.

Even with a slight vacuum leak or intake leak, the IAC and fuel trims should keep the idle steady.

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Old 04-20-2010, 04:06 PM
  #30  
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Originally Posted by moosestang
That shouldn't be happening. A scan tool that can read fuel trims or aeroforce gauge would come in handing for diagnosis.

Even with a slight vacuum leak or intake leak, the IAC and fuel trims should keep the idle steady.



My Fuel Trims have been looked at with Dave from Brenspeed on the phone and they are fine. The few Vacuum lines have been checked.


I dont think 05+ Mustangs have a IAC

Last edited by simplexdesign; 04-20-2010 at 04:10 PM.
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