Pontiac Repair: Car dies, spark plug wires, 3800 engine

Question
QUESTION: I have a 2007 GXP and it seems like when it is 90 degrees or above outside the car will suddenly die or cut out at idle. I have noticed that it will drop down to almost 500 rpm before this happens.  When the car dies the radio will make a loud noise like there is some type of interference.  It hasn't done it on myself but it was 115 degrees heat index the other day and my wife said it would barely take off but once you got up to speed it seemed to run fine. It is not throwing any codes.

ANSWER: Hey Josh:

That is odd these newer ones don't usually have stalling issues. If it just stalls ata stop like a stop light. I would first and foremost try leaning the throttle body and throttle bore. if it's gummed up with carbon it can cause a stall condition especially from the increased load on the engine from the a/c compressor working hard due to the incleased heat load. try that first and see what happens.

Good luck :)


---------- FOLLOW-UP ----------

QUESTION: I don't think it is the throttle body because now when it acts up the speedometer will jump up to about 80 and come back down and the car will die.  Every time it does this the radio will also turn up for about half a second.  I've checked all the wires I can get to and they all seem fine.

Answer
hear are a few more thoughts. we had issues with this power prain in pervious year where the spark plug wires were routed to close to the harness that runs down to the transmission speed sensor the spark plug wires would leak voltage into the engine harness for the transmission and would spike the engine computer. Is this a 3800 engine in this or is it the samll block V8 option?  If it's the 3800 then make sure if the wires have been replaced on this car they are no where near the engine harness it runs down the back side of the engine under/behind the alternator. If it's the small block then forget that part of this.  As for the radio hummmm have you had the scanned for codes are thare any codes in any modules that would leave some kind of a thumb print as to what is going on here. You could have a voltage spike going on here. Did you check the cables on the battery are they clean and tight. How about the voltage sensing module it's on the battery cable and lloks like a power probe clamp. are the 2 battery cables close to each other where it clamps on the cable? if they are try to seperate the cables apart with the little bit of leads they give you to work with. Check the battery ground cable on the body by where the battery sits on the fram rail. make sure it's clean and tight.  Those are a few other ideas. to tel you the truth these newer "W" body cars have been pretty darn goood and pretty much trouble free and stalling is for sure an odity on these.