Skip the auto shop - Our mechanics make house calls

Q: Violent jerking at stop lights

asked by on

Long story short my daily beater has been acting up. Have had the car over 5 years always tried to keep up with maintenance and repairs if needed. Starting December I noticed my car sputtering in and out. I drive a lot so I need to properly address the issue before throwing money at it or clunking it . Anyway started small and barely noticeable but now I don't even wanna drive it since it does it a lot at stop lights when I press the brakes and am waiting for the light to turn green feels like she wants to die on me. After doing online research and having some what of mechanic experience I did the following. Battery was 4 years old so got a new one didn't fix the issue. Checked the alternator by turning car on and removing battery to see if car maintained charge and it did. So I opened the car up cleaned the MAF, throttle body , checked the intake systems for leaks (couple hoses needed to be replaced) replaced air filter, checked all sensors and relays and nothing. So here I am:(

My car has 178000 miles.
My car has an automatic transmission.

Hello There, It sounds like you may have a dirty or faulty idle air control valve. The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor. This is controlled by the car’s ECM which uses this information to make adjustments to the air/fuel ratio depending on various inputs such as outside air temperature, intake air temperature, load and various other things. As you accelerate, your car’s engine is receiving a much higher dose of fuel than when at idle and conversely, when you let off the gas pedal, there is a sudden change in this fuel supply as a result of your foot letting off the pedal. When this happens, the job of the idle air control valve is to bring this deceleration down to a slow and smooth idle rather than suddenly cutting off the fuel supply causing the motor to die. When the idle air control valve is not working properly, this cause a disruption in this process resulting in the engine not being able to idle properly. I would recommend having a professional 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

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・Fair and transparent pricing

Get a quote

What others are asking

Q: Tacometer source for aftermarker tacometer.

Hi there. Since we don't know the brand and type of tachometer you've purchased, its not possible to give you exact instructions. You might want to read this article we've written on how to install a tachometer. It might give...

Q: Green key light flashing, car wont start.

Hello, from what you describe it would appear to me that you may be having an issue with your vehicle's transponder and key. The green key light that is flashing is actually not related to AC at all, it is...

Q: What viscosity oil should I use?

If you have the 1.8-liter engine, then you should use SAE 0W-20 oil. If that is not available, you can use SAE 5W-20, but you should not use this viscosity level in consecutive oil replacements. If you have the 2.4-litre...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...
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.