2006 GT wrench light and floating revs issues

[rangler]

Hello,

This problem has been going on for some time now with several unsuccessful attempts at repair. I would be grateful if anyone has some new suggestions. So far the dealership has updated the PCM tune, replaced the throttle body (TPS included), checked the connections over and over etc. When I get to the dealership the trouble light is not on and there are no codes to read. I have listed the details below.

Background:
2006 Mustang GT manual with FRPP non-intercooled S/C installed by a ford dealership, Roush Stage 1 suspension upgrade, P.I.E. auxillary input module added to Mach 1000 sound system

Problems:
#1 -intermittent wrench light on dash, when this happens the car is driveable but performance is severely reduced, most times the issue will clear when the ignition is turned off and back on.

#2 -the engine rpms do not respond correctly to the postion of the accelerator or will stall at idle. Sometimes while driving the car it will not slow down when I take my foot off the gas pedal. When I put the car in neutral either while moving or stopped the revs may remain at 2-3k or even rise up to @4K or so. While stopped sometimes they will drop to 400 or so and then stall.

These problems are not repeatable or predictable so I can't isolate it down to any specific event. The dealership now wants me to take it in the next time I have an error code so hopefully they can read it at that time. Thanks in advance for any advice you can through my way.

[Hotshot]

So its not the throttle body, the tune or a vac leak huh? Now that's quite the brainteaser....

I had an idle issue, turned out to be a tune issue. Are you sure your dealer gave you the correct tune for your setup?

[GT800]

hmmm this is an interesting one... lets see well it could be the gas pedal assembly but judging by your issue not likely due to the design but possible. i assume your setup has some form of wastegate for the boost. correct me if im wrong im not 100 percent familiar with the whipple setup but if the wastegate is getting stuck open or malfuntioning in some way could cause something like this because it wouldnt be able to build boost causing your loss of power and would cause a rich air fuel ratio possibly throwing your wrench... justa thought

[rangler]

Originally Posted by Hotshot

So its not the throttle body, the tune or a vac leak huh? Now that's quite the brainteaser....

I had an idle issue, turned out to be a tune issue. Are you sure your dealer gave you the correct tune for your setup?

How could I tell if the tune was correct?

[GT800]

did the seyup come with a tuner?

[rangler]

Originally Posted by gt/cs07

did the seyup come with a tuner?

it came with a small black box that had one wire harness coming out of it. there was no lcd screen or buttons on this box.

[05bluestang]

Tip from past expierience, as soon as the light pops, shut the engine off and pull over. The light should stay on when you restart (it did for me) and you should be able to pull the code

HTH

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[rangler]

Originally Posted by 05bluestang

Tip from past expierience, as soon as the light pops, shut the engine off and pull over. The light should stay on when you restart (it did for me) and you should be able to pull the code

HTH

Sent from my EVO 4G using Tapatalk

that's the thing. the light and trouble code resets at that point.

[05bluestang]

Well sounds like a vaccuum or intake manifold leak to me, check any of that? You may have a manifold gasket that either got pinched or ripped and opens a gap when the engine gets warm.

My 0.02c

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[GT800]

might wanna get yourself a scanner and just just keep it in the car for the next time it does it.