[truspeedinc]

I know there is a thread for iac valves but mine is kinda unique I think while driving the car I will push the clutch to change gears and the car will idle at the Rpm reached and will not die down how ever on start up it will idle up and Cole down and stay there. The car has pi heads and all with comp cams 286's, when checking it with a scanner I get the p0171 and 0174 codes the rear o2 is off.

 

[Dubwhat]

http://www.allfordmustangs.com/forums/4-6l-tech/361566-98-gt-weird-idle-stuff.html

Read that thread and watch/listen to the videos. Does it sound similar?

 

[CaseyT]

Read that thread and watch/listen to the videos. Does it sound similar?

Dubwhat, I watched the video and wondering if you figured out what was causing it? Because I'm having the same issue, but I've changed IAC three times, changed TPS, and changed PCV valve and its Still doing it

 

[Dubwhat]

Nope. Not a clue yet. Working on trying to figure it out.

I wonder if the plenum needs to be pulled and cleaned. From what I have read, they get pretty carbon'd up.

It has something to do with the way the car is interpreting the idle. I would figure TPS but that's just how far your foot is into the peddle. It might be a MAF issue...have you tried cleaning yours yet?

 

[CaseyT]

Yes I have a brand new MAF. And I took the plenum off and cleaned it with both seafoam and throttle body cleaner, I haven't tried a new egr yet but I wouldn't think that would affect idle? I'm gonna try pulling it off and seeing if there's any cracks on the manifold even tho the manifold is aftermarket.

 

[Dubwhat]

I just applied a Bama tuner for performence to my car, and the idle very SLOWLY comes down. But mine RARELY does it. It only happens from time to time and I notice like a burp in the way the car runes before it does it.

 

[truspeedinc]

Found out what was causing it an exhaust leak between the egr pickup and the delivery piping.