Q: Car vibrates/shakes when sitting still in idle (in gear or in neutral).

asked by on

After having my car serviced for oil change, tire rotation and air filter replacement, as I was leaving the service center my car had a new engine vibration/shake while in park or neutral in idle. If I rev the motor to 1000 rpm the problem seems to go away. I am not getting any engine codes. I have since replaced all motor and transmission mounts (3 were broken anyway) but this did not make any difference. I have taken the car to Roger Beasley dealership who had it all day and could not discover the issue. It drives fine. Any electrical load while sitting still seems to make the vibration worse. Lights, fan, AC, power windows, windshield wipers, even pressing the brake pedal. This is driving me crazy not to mention making me concerned that something serious is about to happen. Any ideas?

My car has 94000 miles.
My car has an automatic transmission.

This sounds as if you have a low idle condition. I can say your car isn’t likely to suffer a catastrophic failure because of this. With a condition such as this, it is normal for it to run rougher when electrical components are tuned on and it is normal for a car to run rough when the idle is to low.

My first instinct here is to clean the throttle body, fully warm the car, connect a scanner, and command the IAC (Idle Air Control) valve to move the idle high and low to see how it responds. 9 times out of ten, I have found this to fix this symptom.

Other things to consider:

Some more advanced possibilities include the MAF (Mass Air Flow) sensor, which is the primary sensor the PCM (Powertrain Control Module) uses to calculate air-fuel ratio. Although, I wouldn’t go replacing the MAF without a thorough diagnosis from a certified technician.

I’d consider allowing a certified mechanic to diagnose your rough idle if you decide to get this fixed. You’ll have a clear idea of what will need to be fixed after doing so.

Good luck!

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. Car vibrates/shakes when sitting still in idle (in gear or in neutral).

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: When first starting the car for the day, it wants to bog down intermittently only at idol. it never dies but

It may be time for a tune-up and cleaning of the induction system. Carbon build up around the throttle plate or worn spark plugs may cause the engine to run a little rough, especially on a cold start. Consider hiring...

Q: Lost power while driving. Wont crank. Check engine light is on.

Hello, thank you for writing in. There are several systems that may be malfunctioning. You should narrow in on the charging system first. Have your battery and your alternator checked. This can be done at home or at your local...

Q: Oil leak above driver side exhuast manifold

The most common oil leak on these engines is the valve cover gaskets. The gaskets are a mix of rubber and metal or plastic and the rubber will get hard and will not seal very well when the engine is...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.