When my engine is dead cold, the idle becomes quite high (2000 - 2500 rpm) after I initially pull away and but only for 1 to 2 minutes.
It happens 1) while approaching a stop sign with the clutch in (should I stay at that stop sign for a few seconds the idle drops back to the normal range)
and 2) between gears (should I pause for a second or two while shifting).
The symptoms are like there of a sticky accelerator pedal or throttle cable although I don't believe that is the problem.
I have scanned the codes, nothing. I have cleaned the throttle body and replaced the IAC valve with a brand new GM unit. I have a new fuel filter, air filter and new AC Platinum spark plugs. Any suggestions as to where I should look next?

Andrew

99 Cavalier Z-24
2.4 L 5 speed
295, 000 KM

Vacuum leak. One of the vacuum hose is cracked or unplug.



Gilles
2.3 Ho

tps?maybe


15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"

I am not sure if this is related or not but it seems that my fan motor is coming on alot lately and the motor is not running hot.

I will check the vacuum hoses and tps tomorrow when it is light. Thanks.

The way i know something is about to go wrong, is that my cooling fans will turn on, and my Traction will be turned off as soon as i turn on my car, even if its not in hot soak. But yah, it could be your vacume,

From what I was explained if the TPS sensor was bad then the car would ide up and down so i don't think it is that



96 CAVALIER Z24 UNDER CONSTRUCTION

I checked for a vacuum leak, all lines appeared to be in good shape and there is nothing unplugged.

Does this only happen when you have it on full defrost? I ask because that turns on the AC compressor, which forces the fan on. My car does this once in a while after flashing a new tune with HPtuners, idles funny with the AC on for a while till it relearns.


15.3 @ 89.97mph, 14's on the way?

I can sit in the driveway and rev the car (cold) and the idle returns to the normal range every time and right away. However, when I put the car into motion, the idle acts up (as described at the beginning of this post).

It appears that the defroster is not contributing to the problem because it is not on when the problem is happening.

It must have been a cold weather related thing. My car worked normal today. Go figure.

I am having a similar problem. I definitely think that it is electrical. When my car goes into motion the idle goes to about 2000rpm and returns to approximately normal after sitting for a minute. Then it starts back up once the car starts rolling wether in gear or not. It is not the tps, IAC, MAP, or coolant temp sensor. I have replaced all of these and the problem does not go away. The problem presented before I installed my SC and is still there. Could it be a bad alternator. I am almost positive that the problem is electrical.

It's a software problem. Try resetting the computer, or fix it one and for all by unplugging your IAC valve once the RPM has stabilized (~900).

2002 Cavalier 2200 5spd

For all of the part changers here is a little tip to save a lot of cash buy a book and test the sensors and see if there bad before getting another one trust me it's worth it!


My car--->http://www.cardomain.com/ride/2569452

Quote:

It's a software problem. Try resetting the computer

How does one reset the computer on a 99 Z24?

You should be able to reset it by unplugging the battery for a while.

I have your exact same issues on my 2200, supposedly it's GM's idea of an anti-stall feature. I simply unplugged my IAC and haven't had a problem since. It doesn't wear the clutch as badly and mileage is a little better too.

2002 Cavalier 2200 5spd

I unplugged the battery for two hours today. There is no difference.

Reseting the computer does not help. Here's what's going on with mine lately. My fairly new battery died yesterday after sitting for just 2 days. And my car shocks the piss out of me every time I get out, meaning that there is a short somewhere in the car. Also, I noticed that my throttle position sensor has no output signal when I release the E-brake and my DRLs turn on. Any suggestions as to where the short may be? I believe my problem is due to my car not getting a tps signal. My buddy seems to think my ecu is bad because he has an earlier generation cavalier that did the same thing. I think its a short somewhere causing all of this mayhem.


That which does not kill you makes you stronger!

I found a frail vacuum line at the front of the throttle body. I will know tomorrow upon cold startup as to whether or not that solved the problem. I will keep you posted.

I replaced the frail vaccuum line, cleaned the negative battery cable at the battery and at the block, and reset the computer. The car still idles higher than normal, however not as high as it did last winter. I think I will have to live with it for now.