Idle RPM fluctuations

[Jpye11]

So I just picked up my 2007 GT500 w/1300 miles on it. It currently has ~2600 miles on it. After I have shifted through some gears, when I started coming to a stop and put my clutch in the RPMs fluctuate anywhere from 500 - 1000 repeatedly for about 15-20 seconds before they settle down. The previous owner had this same problem, sometimes it would shut his car off also. He took it into his Ford dealership to check it out and they said it was just loose screws on the CAI. I have checked all those screws with nothing loose on the CAI. Any suggestions or is this not something to worry about?

Thanks

 

[NightRide]

That's not too much movement, mine will idle high when cold above 1k then settle down to 800. What are your mods? If you have an aftermarket throttle body I would get a new tune.

 

[bull3441]

do a check of the intake from the TB down.

 

[Bulldogger]

I went through a similar problem. First start off by checking the voltage at the TPS sensor. Normal range should be 1.19v - 1.31v. If the voltage is at either end you may start having some high or low idle searches. I would set the TPS at 1.26v.
My VMP throttle body had the set screw loosen on top releasing tension on the throttle stop. The car had hanging idle when ever slowing then drop and come back up to about 800rpm. After sitting for two days it refused to start and threw codes 2104 and 2112. After fixing and setting the voltage, the car drops idle to 800 once the pedal is released no more high idle hanging and no more idle hunting.
If this doesn't help next check would be the MAF calibration in the tune, may need to be adjusted depending on which CAI you have.

 

[Pure_Evil_GT500]

^^^^ that's what fixed my problem too...!

 

[Jpye11]

Thanks, I'll try this when I get home.

 

[09Troublemaker]

congrats and welcome
perhaps some pics;-)

 

[Jpye11]

Thanks Trouble, here she is. Sorry for the size...

 

[Blacksmoke]

With the GT's a dirty throttle body could cause this as well.
If they looked the least bit dirty on the inside odds are they were dirty enough to
cause this problem.
Might check that out with your GT500 as well

 

[tommy s]

I went through a similar problem. First start off by checking the voltage at the TPS sensor. Normal range should be 1.19v - 1.31v. If the voltage is at either end you may start having some high or low idle searches. I would set the TPS at 1.26v.
My VMP throttle body had the set screw loosen on top releasing tension on the throttle stop. The car had hanging idle when ever slowing then drop and come back up to about 800rpm. After sitting for two days it refused to start and threw codes 2104 and 2112. After fixing and setting the voltage, the car drops idle to 800 once the pedal is released no more high idle hanging and no more idle hunting.
If this doesn't help next check would be the MAF calibration in the tune, may need to be adjusted depending on which CAI you have.

Do you remember what color wires to look for when checking the voltage at the TPS sensor ?? I think there's like 4 coming out ? wondering wich 2 to put volt meter on ??