I’m driving a seven-year-old Japanese car. Every time I start the engine, the engine speed goes up to 2000rpm. When I stop at a traffic light, the speed stays at 1500rpm for about three seconds before lowering to about 950rpm.
I tried switching the air-conditioning on and off, but it makes no difference. Why is this so and should I worry?
Idling engine speed is electronically controlled. It does not require any adjustment unless there is some modification, such as the installation of a special air filter.
Check the throttle cable to see if there is any obstruction. If there is none, the fault may be related to the throttle body.
It would be best to send your car to a workshop for a proper diagnosis.