Skip the auto shop - Our mechanics make house calls

Q: Very rough idle goes away at speed. Can it be the cam solenoid?

asked by on

I have a 2002 trailblazer with 115k miles.one day the car started running really rough at low idle and shakes bad,seems to run smoothly at higher revs...wondering what it could be

Hey there. This may be related to a dirty or failing idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. This is all controlled by the idle air control valve. This can also be caused by other things as well such as low fuel pressure or dirty or leaking fuel injectors causing an over fueling situation. I would recommend having an expert from YourMechanic come to your location to verify the cause of the rough idle and replace the idle control valve if faulty.

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

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: Engine is running horrible with stalling and noises under load.

Hi and thanks for contacting Your Mechanic. As for the engine misfiring and having an issue with the rough idle, there could be a vacuum leak on the engine. Check all of the vacuum hoses and the intake to see...

Q: VVT (variable valve timing) Solenoid and Check Engine Light codes P0300 and P0011

Hi there. Through your research you probably discovered that there are multiple causes of a rough idle and the Check Engine Light beyond the VVT solenoid. If you replace the second bank solenoid, it may improve your issue, but...

Q: the car revs high and at stop signs while slowing down then idles down suddenly and sometimes stalls, whats the cause?

The engine intake manifold seals or the intake tubes between the mass air flow sensor and the throttle body may have a leak that you cannot hear, but could be found using a smoke machine designed to find the leaks....

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...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...