Q: Car is randomly misfiring

asked by on

i have random misfire only happens occationally for a split second accompanied with a ignition light flash momentarily otherwise the car runs perfect

My car has 106000 miles.
My car has a manual transmission.

There are a number of things that may cause this such as a faulty or dirty mass air flow sensor, a potentially a bad idle air control valve, or dirty fuel injectors. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor. When this fails, this can cause an imbalanced air/fuel load to be supplied to the motor which often times results in the engine starving for air or fuel. This is what causes the hesitation or loss of power you describe. This can also cause the engine to struggle to idle for the same reason.

The idle air control valve is located on or near your intake manifold that monitors the air intake as it is mixed with fuel prior to being injected into the engine. This valve is controlled by the vehicle’s computer which 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. However, when the engine RPM drops below the normal range of 800 RPM (for most cars), it is more than likely that you are dealing with an IAC valve problem. In cases where this valve is clogged or is failing, your vehicle will stall instead of slowing to an idle after the release of the throttle.

If you need some assistance, I would recommend having an expert from YourMechanic come to your home to properly diagnose the misfire you have described for an accurate repair.

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 is randomly misfiring

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: Q: Engine won't start

A number of things can cause a crank / no start condition. First, you must check for the basics. Is the engine getting fuel? If not, the problem could be a bad fuel pump and/or bad fuel pressure regulator. ...

Q: Misfire, mechanic wants to replace whole cylinder

I suggest getting a second opinion. I would get a quote to replace the entire engine with a remanufactured one. You will pay less in labor but more in parts. This way you will have a new motor, not a...

Q: Sulphur blocking the catalytic converter

Hello. If you had an injector coil issue, then that will usually cause the converter to become clogged and fail. If it is clogged, then it needs to be replaced as driving it will not clear it up. You will...

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...
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...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...