Skip the auto shop - Our mechanics make house calls

Q: Idle and acceleration problem

asked by on

When the truck idles the rpms fluctuate up and down occasionally. When I give it a little gas it sometimes stops. And when I'm taking off from a stop and not giving it a lot of gas the Rpms go up and then back down and then up again and then the truck goes
My car has an automatic transmission.

What you are describing sounds like 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 and 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 with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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
  1. Home
  2. Questions
  3. Idle and acceleration problem

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: My truck is getting no spark

Hi there. If you are not getting ignition spark at all, the problem is typically going to be caused by a malfunctioning ignition coil or distributor. Depending on how severe the backfire might have been, it is possible that it...

Q: Car won't start - 2013 Dodge Charger

Hi there. Fuel pressure would be a good thing to check out as lack of fuel pressure would indicate a failed fuel pump. Other things that may cause the vehicle to stall are a camshaft or crankshaft position sensor and...

Q: how to clear diesel fuel out the motor

Running the vehicle with part diesel can damage the engine so remove as much of the fuel as possible. That means that the fuel tank has to be drained as completely as possible. Obviously, when draining the fuel tank exercise...

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...