idle problems
 

My mustang has the following mods:
cobra intake
gt 40 heads
hypertech superchip
mac underdrive pullies
full 2 1/2" pipes
headers

Since I replaced the intake and heads (did bearings at the same time) The car does not want to idle at stop light, it runs great when in motion, no problems..... but when left to idle it does not want to... any sugestions

The car is still a speed density car and is not cammed.

you need to be more specific.

it doesn't idle in what way?

does it die? does it surge? does it idle rough? does it idle too low/high.

expand a little and the problem will be more easily resolved.

First things to do are to remove the Idle Air Control (IAC - on the side of the throttle body) and clean it out REALLY good. Make sure there is NO gunk left in it and the plunger is nice and free. Then reset/check your idle adjustment.

Then take apart the ten-pin connectors (black and white connectors hanging on the back of the upper intake) and clean the contact surfaces real good and spread the male connector a little for better contact.

Then remove your EGR valve and be sure the seat is clean enough for the valve to close. If not clean it up too.

Then check to be sure your Throttle Position Switch (TPS) is at or below .97vdc at idle.

Thanks I will give it a try.....

By not Idling I mean..... it will start up an run just fine, but it will stall out after it has been driving ie// at a stop light

In that case it is your IAC motor or EGR valve

I doubt it's your IAC because once the vehicle is warmed up, it has very little effect. It could be a sticking EGR valve. Try disconnecting and plugging the vacuum to the EGR when it's cold, and see if the problem goes away. If it does, replace the EGR. If it doesn't, try removing the ECM chip, and see if that makes a difference. My money is on the EGR.

Take care,
~Chris