My car was parked for more than three weeks.

Once I started the car, it never idle by itself. I had to give it some gas to keep it running. Once I let off the gas it will stall.

I used my scan tool and no codes.

I am suspecting the IAC. Doesn't it throw a code if the IAC is defective.

I will have to measure the resistance of the A B, C D terminals (must be 40-80Ohms).

Is it possible that the IAC could caught some dirt and just needs cleaning or replaceing it is a must.

 

Just an idea, but you prolly already thought of this. Did you try putting some new gas in and maybe some octaine boost ? This helped my car once when it sat for awile and wouldn't idle very well on it's own.

 

Measured the resistance across terminals A and B then C and D of the IAC and found them much below the lower limit of 40 Ohms.

Removed the Throttle body and then removed the IAC valve and found the valve pintle jammed ( not moving in or out).

Cleanned the Throttle body and IAC valve housing with gasolen and carb cleaner. Installed a new IAC valve and started the car and it ran perfect.

Conclusion, it was the IAC.


Note: here is another way to check the IAC using the scan tool, found it in the HAYNES manual, although I didn't try it:

"Connect the scan tool and switch to Idle Air motor position mode and monitor the steps.

Scan tool should indicate between 10 and 200 steps depending on RPM range. Let it idle , observe the scan tool steps and snap the throttle to 3500RPM. Repeat several times and observe the steps when the engine goes back to idle. The readings should be withing 5 to 10 steps each time. If the readings fluctuate greatly, replace the IAC".

 

mine jumps up and stays at 2k sometimes but other times it idles fine..