Skip the auto shop - Our mechanics make house calls

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.

A: This may be a sign of a leaky injector or p...

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?

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: Loss of power like misfire under any load

Hello. To start, you mentioned that you had switched out the fuel injectors. Have you checked the fuel pump and filter? Being 16 years old, the vehicle may be struggling due to lack of fuel pressure. The Check Engine...

Q: Motor oil.

Hello. It is definitely a good idea to use synthetic oil in your engine. Synthetic oil will work better with the design of your engine and will keep the variable valve timing system working as good as possible. Using a...

Q: Starting issues. My car won't start right away after sitting over night or for a few hours.

When you say that it won't start, are you saying that the starter doesn't turn (aka it doesn't crank), or are you stating that the vehicle attempts to start (or turns over) but fails? These are two different issues. The...

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 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...