Skip the auto shop - Our mechanics make house calls

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.

A: If the symptom seems to clear up at higher ...

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?

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: misfire cylinder 1 and 2

Hello. A misfire can be caused by a variety of components. Due to the oil smell we can focus in on a few potential issues. If you are noticing any kind of smoke during acceleration or deceleration, then you may...

Q: Power steering

Hello. This can be caused by a few different parts in the steering system. Most of the time it is caused by either a failing rack and pinion or a bad ball joint, tie rod, or a bad strut mount....

Q: Turn off theft lock Ford Escape 2001

If you still have one of the old programed keys from the other steering column all you have to do is hold it near the ignition when you turn on the key to see if it starts this way. If...

Related articles

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...
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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.