Q: Q: My car idles rough when stopped

asked by on

My truck is idleing really rough only when stopped. It wants to die if stopped to long I changed the idle control valve and all 6 coils but it didn't help

My car has 187000 miles.
My car has an automatic transmission.

This may be a sign of a leaky injector or potentially an incorrect idle air adjustment. A leaky injector can cause a rich fuel condition as it may leak too much fuel into a cylinder not allowing the combustion cycle to burn the fuel evenly resulting in excess unburnt fuel being unused and momentarily flooding the motor causing this kind of rough idle. When this happens, you may notice a bit of black smoke coming from the exhaust as well as a slight fuel smell.

This may also be a slightly misadjusted throttle plate. The throttle plate is adjusted at a specific angle to allow just the right amount of air into the throttle body at idle speeds. This is done by the work of an actuator motor that electronically adjusts this. When this is not working properly, this may cause a rough idle due to an unbalanced load of air and fuel to be supplied to the motor.

To avoid any unnecessary repairs, I would recommend having an expert from YourMechanic come to your location to diagnose your rough idle firsthand.

Was this answer helpful?
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. Q: My car idles rough when stopped

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: Truck cranks but won't start. Has good fuel pressure and spark. Engine will crank and run if you pour gas in the throttle body.

Hi there. Check the injectors harness with the key on and the engine off without trying to crank. There should be a voltage on one side of the harness supplying fuel to the injectors. Then crank the engine and back...

Q: My car steering wheel locked up then all my dash board lights came on. The low coolant came on the it died out

The sequence of events that you are describing can be due to an electrical failure, overheating, or mechanical issues. To obtain a pinpoint diagnostic, the recommended service is an engine stalling diagnostic. If you request that service, the responding certified...

Q: My car needs new engine, should I make the repair or sell it?

Hi there, thanks for writing in. This is one of those questions that's honestly very difficult to answer. If you're really fond of your truck, then making the investment to replace the engine might be a good decision. However, if...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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 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...