Q: it has a misfire when at slow speed

asked by on

it has a missing to it at a slow speed when u get to 35 or 40mph it is gone

My car has 182000 miles.
My car has an automatic transmission.

If the symptom seems to clear up at higher speeds, this may be related to the idle air control valve which monitors air/fuel ratios at idle an lower speeds. This is a unit that 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 nearing its replacement age, your vehicle will stall instead of idling after the release of the throttle. I would recommend having an expert from YourMechanic come to your home to replace your idle air control valve.

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. it has a misfire when at slow speed

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: Intermittent cylinder misfiring on a '98 Grand Marquis

What you should do, if you don't have the equipment and you don't understand it is to call a professional to take a look into your misfiring problem for you. Mechanics, like those from YourMechanic and myself, we've been doing...

Q: How do i test the speed sensor for my car?

Hi there. I wouldn't doubt that the issues you are having are electrical. However, there isn't a general "test" for voltage on a dash cluster that is completed. Typically a professional mechanic would download stored error codes to determine if...

Q: Do I need to keep refrigerant in my A/C compressor during winter months

The refrigerant inside the compressor has nothing to do with the compressor pulley turning freely when the compressor is not engaged. If the pulley is not turning free then the bearing inside the pulley will need to be replaced. If...

Related articles

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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...