Idling weird

[Euphman06]

Quick question... When I start my car up in the morning, or if it has been sitting for awhile, it revs at about 1500 rpm, when it should be down around 850. It doesn't go down until i tap the gas, and then it will settle. Maybe I need a tune up? Sometimes, when it starts when it's warm, it will dip up and down a little before settling. Any help?

[Manarius]

My car does the same. I just tap the gas every time I get in....it's a habit - I do it on every car.

[realfinn]

You are probably just seeing a cold idle response. Most cars have the ecu programed to adjust the idle up when the block is cold and then taper it off as you reach a higher block temperature. If you start the car up and let it run for 2 minutes or so at idle without tapping the gas it should drop down lower and lower until it reaches 850 rpm or so. Some people feel that letting the engine hit the low idle before driving is better for the engine. It allows oil pressure to rise and for the coolant to start flowing the full loop. Other people just jump in and take off down the road.

[Radial GT1]

It should stay at 1500 for a couple minutes. Like mentioned already it get the block warmed up, but "most importantly," it gets the cat warmed up to be more effective when the pollution levels of the exhaust are the worst. Unfortunantly at the sacrafice of the engine. -20 below zero and revving to 1500 right off the key makes me and my valves angry!!