2001 Z24 idle high

09-12-2011, 07:26 PM
My son just bought a Cavalier Z24 manual transmission and the idle is at 1,100, if you kick the gas and release it goes up normal and down to 1,400 and after a couple of seconds start going back to 1,100. Sometimes while driving the idle stays up at 2,500 rpm and won't go down, the only way to bring it back to 1,100 is to turn off the engine and started again.
Can somebody please help me with this issue, by the way I changed the map sensor and the hose and no change.

Thank you

Tech II
09-12-2011, 09:46 PM
Check for codes?

Check for vac leaks?

Check for sticking Throttle plate?

Bad Iac?

09-13-2011, 08:29 PM
Thre is a MAP sensor code but I replaced the MAP sensor and the code came back. There are not vacum leaks. I will check the throttle plate.
Can a bad IAC can make the idle go so high? I thought a bad IAC give low idle and makes the engine stall.

Tech II
09-13-2011, 10:12 PM
IAC's can fail many ways....not work at all...increase, but no decrease.....decrease but no increase....An IAC tester would verify this....

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