grand am stumbling and dieing

[skipice]

Hey there, I am new to this forum so I hope I do everything right. I have a 93 grand am 2.3L Quad 4. When your driving along the road you couldn't ask for a better ride, then you hit a stop light. The check engine light comes on (everytime the engine idles), you start to go from the stop light and she will stuter and sometimes die. While she is stutering you can pop in neutral shut the engine off turn it back on and it goes fine, until you idle again. Trouble code says I.A.C. so I have changed the IAC valve three times (gets expensive), I have also changed the O2 sensor, The TPS sensor, the main computer, the spark control plate (not sure what it is called, the plate at the top of the engine that connects to the spark plugs), taken the throttle body out and cleaned it, changed spark plugs, changed the air filter. I have spent alot of money and the problem is getting worse. The only thing I can think is fuel pump, or filter, also I was told possibly fuel rail, or MAF sensor, where is the MAF sensor? Please help before I spend more money and have to go to a padded room with a nice white jacket.

[FormulaLT1]

It sounds very much to me like you have a short in the IAC wiring. Have you had the IAC counts scanned?. or measure the voltage across the terminals with the ignition on? to check that they are steady with no drops in voltage. If its setting a code for IAC and its affecting idle the problem with IAC circuit still remains. If all checks out with wiring then it could be a bad PCM although just setting that one code is almost unheard of. Good Luck. Also welcome to AF.

John

[skipice]

What should the voltage be? and do you unplug the IAC and measure across those terminals? I already changed the PCM if that is the main computer under the dash .

[FormulaLT1]

OK you should have 4 wires, 2 high coil voltage and 2 low coil voltage or grounds. The low current or ground will be identified by a black stripe or being completely black. You can take a voltmeter and check the voltage to the other wires and use either the block or battery terminal as your ground. with the ignition in th on position you should check the voltage of both using the terminal with the black stripe as the ground as well as the battery black terminal. I believe the voltage should be either 12 volts or 5 volts can't remember which for sure but I think its 12. If you see a jump in voltage or difference from the battery and terminal voltage when used as a ground. You probably have a break in the circuit somewhere. Good Luck.

John

[skipice]

Thanks I will give a try tomarrow

[skipice]

I measured the voltage between the hi an lo on both sides one said around 11 and the other said negative 11. there was a slight difference if I used the battery as a ground as apposed to the lo side terminal but not much. Help!!!

[frpthlgy]

I had the same problem with my 91 Pontiac grand am 2.3L quad 4 DOHC and it was my torque converter clutch solenoid. which is on the side of the tranny. After i replaced it the car stopped stalling out.

[skipice]

Thanks I will give it a try.