Skip the auto shop - Our mechanics make house calls

Q: van runs lean or low on first start of the day.

asked by on

the first time I start my van every day, I get a low rough idle for a few minutes. then it is totally fine all day. when I restart my van after having driven at regular distance at normal temp it revs high for a couple seconds and the temp gauge goes up to nearly 3/4's full and steadily lowers to normal temp. perhaps a coolest temperature sensor?

My car has 145000 miles.
My car has an automatic transmission.

A: This may be a sign of a failing idle air co...

This may be a sign of a failing idle air control valve. 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.

The overheating may be caused by many things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. 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

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: My car has idling problems that come and go

The biggest problem with inconsistent engine idle issues is trying to diagnose them. However, there are a few other components you haven't listed that might be faulty. The first is the throttle position sensor. It's likely your Mitsubishi has an...

Q: When I rev it it has a hard time.

This is tough to diagnose without more info, however it could be potentially some things like a faulty mass air flow sensor or throttle position sensor. Either of these two parts will have a negative impact on fuel/air flow which...

Q: My XC90 Volvo 2006 I thought was the PCV system so I had all the hoses there changed as well as the oil catch can but my engine li

There are more than ten principal causes of rough idle and that list doesn't include potential mechanical faults such as uneven cylinder compression. By far, the most efficient strategy to resolve this issue is to request a rough engine idle...

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...
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...
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...