Skip the auto shop - Our mechanics make house calls

Q: Idles high without accelerating

asked by on

My engine was replaced in my 2002 Safari, but I don't know if the mechanic used a 2002 used engine or newer one. When I accelerated from a stop I felt the idle gradually increase speed until it reached about 50 mph. And I didn’t even press on the gas pedal! When I stopped the car it idled down to normal until I took my foot off the brake. When it got to around 3 mph the idle started to increase again. I replaced the oxygen sensor on the passenger side and the idle air control valve. I was going to clean the EGR valve but couldn't find it. That’s why I think it might be a newer than 2002 engine. I’ve read in that 2003 and newer Safaris don't have an EGR valve. Can you help me with this problem? What should I do?

A: Hello. Thanks for writing in about your 200...

Hello. Thanks for writing in about your 2002 GMC Safari. There are several components that may be causing this problem. There could be a bad throttle position sensor, a throttle cable that is sticking, or a vacuum leak. All of these things may cause the idle to increase on its own. My suggestion would be to have a certified technician, like one from YourMechanic, complete an inspection of your rough idling issue in order to pinpoint the problem.

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・Save up to 30%

Get a quote

What others are asking

Q: Engine puffs blue smoke; thumping noise at highway speeds

Hi there, thanks for asking about your 2004 Infiniti FX45. The blue smoke you notice on initial start-up is likely caused by worn exhaust valve stem seals. They allow a tiny amount of oil to get into the combustion chamber...

Q: Truck idles poorly, starts jumping

There are numerous potential causes for the symptoms you are having. The first thing that comes to mind is a vacuum leak (unmetered air allowing the engine). Vacuum leaks are noticeable at idle and not under load while accelerating. There...

Q: Car overheating/fluctuating on temperature.

Hello, thank you for writing in. There are several other components that can cause a malfunction with the cooling system. You are in the right realm of thinking however, and there is likely a bad circulation of coolant or air...

Related articles

P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.