Skip the auto shop - Our mechanics make house calls

Q: Car is not idling smoothly

asked by on

My car is not idling smoothly. While idling, it bounces between 700 and 900 RPM. I have replaced the wires, spark plug, and fuel filter. I think I checked the hoses. I also just changed the upper and lower manifold seals. I have noticed that there are small fluctuations when I am driving on the highway while using cruise control and on flat land. I want to solve this myself and not go to a mechanic. Any ideas?

A: Hello. This is typically caused by either a...

Hello. This is typically caused by either a dirty throttle body or a bad throttle position sensor. I typically start by cleaning out the throttle body. That will usually take care of the problem. If it persists, I will use a scan tool to monitor the throttle position sensor signal to see if it is failing. That should be the problem. It can also be the air flow meter, but that is not as common. If you want to have someone take a look at it, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your idling issue.

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 running rough

Quite a few things can account for an engine running rough. It could be just one cylinder misfiring, or multiple. If the Check Engine Light is on, the computer has detected a problem and the code(s) will help narrow it...

Q: The car cranks a lot, turns off while idling, gas smell in the car

You need to have the fuel injection checked to see if the system has a fuel injection leak or a pressure regulator leaking. The fuel system, including the filter and pump lines, needs checking to see why you are smelling...

Q: What could be the cause of my car not starting?

Hello there, thank you for asking about your 1999 Pontiac Grand Am. This car's engine is known to have a problem with engine speed sensors like the crankshaft and camshaft sensors. The fuel pump is also known to have issues...

Related articles

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...
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.