Skip the auto shop - Our mechanics make house calls

Q: idle is high after driving

asked by on

i am stumped as to why my 92 ford explorer idles very high after driving it. upon startup, it will idle around 500-700 rpm. after i drive it for any fair amount of time (5 miles or more), i will shift into park and the idle goes up to around 1000-1200 rpm. just did an oil change recently, brand new spark plugs, checked pcv valve (still good). no vacuum leaks. what could be the issue?

My car has 243000 miles.
My car has an automatic transmission.

A: Hey there. Normally a vacuum leak is the mo...

Hey there. Normally a vacuum leak is the most common cause of a high idle but many issues may cause this. Other possible causes of a high idle are improper sensor inputs, an idle air control valve, a faulty engine coolant temperature sensor, a stuck throttle body, a throttle body cable stuck, a bad power steering pressure sensor, AC high pressure sensor or a problem with the ECT (electric control transmission).

As you can see, many different systems cause a high idle condition. With the high idle not occurring until after the vehicle has been heated up, it appears there may be a heat related fault such a sensor reading improperly once it gets hot, or an intermittent issue with the IAC sticking sometimes. A complete inspection will be the easiest way to diagnose your high engine idle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: When looking at the Truck Engine my fan spins to the left which way would I turn the bolt to loosen it on a fan clutch

Always loosen the fan in the same direction it turns. You may need to have the holder and large wrench. You may need to shock the fan to the left while holding the fan pulley. I usually leave the belt...

Q: How do I adjust the collision warning chimes?

The collision warning system is a very important safety feature that alerts you when your vehicle is in danger of a collision. The system alerts you with both a warning light and a chime, but you can turn the chime...

Q: My car is losing all engine power off and on when driving

Hey there. With a problem like this, it is a great idea to start with the fuel system. The fuel pump and filter should be checked. These need to be replaced together anyway. Depending on how many miles are on...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...