rpm's rising

[afwildcat]

Sometimes when I start the car, it idols normally (around 700RPM). After I drive for a while the idol speed will be around 1200-1500 RPM. The engine sounds like I still have my foot on the gas. If I turn off the car and restart it, it goes back to 700RPM. Any help would be much appreciated. THanks

[gapboi210]

what temp is it at when it idles high?

[afwildcat]

normal temp - temp does not seem to matter

[Kblairplus5]

Originally Posted by afwildcat

Sometimes when I start the car, it idols normally (around 700RPM). After I drive for a while the idol speed will be around 1200-1500 RPM. The engine sounds like I still have my foot on the gas. If I turn off the car and restart it, it goes back to 700RPM. Any help would be much appreciated. THanks

My 97 Malibu has started doing the same, but now it's idling up higher and when I turn the car off and then start, it doesn't go away. It takes awhile for it to idle back down. Did you find any help for your problem, mine has just started..........please let me know?

[burly]

This can be anything from stuck throttle position, dirty air filter , clogged fuel filter to fouled plugs, hot engine (fan on which runs alternator faster which idles faster) or bad O2 sensor. I would start with a basic tune up if you have not done so within the last 30k -> fresh oil change, new air filter, replace the fuel filter if you haven't within the last 30k, check the plugs and wires, check the serpentine belt, run some fuel injector cleaner through on your next tank w/ some good 87 octane gas. If none of this fixes it (but no worries, it still is good maintainence) and the engine isn't hot and the A/C isn't running, then it may be time to have it checked further. Engine management systems now-a-days are very accurate as long as their readings from sensors are accurate, so they don't tend to just overrun by a several hundred RPMs.

Have you noticed any other issues - poor MPG, less acceleration, studdering ... ?

[bearcatdon]

Good advise Burly. I would add a good visual check of all vacuum lines and the pvc shaker test to that list.