Skip the auto shop - Our mechanics make house calls

Q: Erratic engine idle - 2005 Dodge Dakota

asked by on

When my ac is off my engine idle is just fine. But when the ac is on the idle is very erratic. I have a feeling it's the iac valve because when I pulled it out it had a bunch of carbon on it. I cleaned it best I could and it's still the same.

My car has 129000 miles.
My car has an automatic transmission.

As you have said, this may be related to a dirty or failing idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. 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. This is all controlled by the idle air control valve. When the engine RPM drops below the normal range of 750-800 RPM (for most cars), this may indicate a dirty or faulty idle air control valve.

In your case, this may be related to the valve not maintaining the proper voltage or connection in which case it may need to be replaced. I would recommend having an expert, such as one from YourMechanic, come to your location to determine whether the idle air control valve is faulty replace it if so.

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: Where is the canister purge selinoid located at?

The EVAP system is located in the rear of the vehicle near the fuel tank, which may be part of your problem in the event there is a leak in the EVAP system. Your car has a small purge valve...

Q: My radio and a/c turn off randomly. When I hit the steering wheel really hard, they come back on. What is my issue?

There is an electrical malfunction in the circuit(s) and a possibility is a loose or high resistance connection. A bad ground connection is a possibility, too. Whatever the cause, a Mechanic would simply trace the circuit, using the wiring diagram...

Q: Cyl 4 misfire 07 dakota 3.7l v6, did plugs, coil, injector, inspected lifters no kicked rocker arms, wondering best route of next

I can think of a couple of things that could potentially be causing this issue. If you have an intake manifold gasket leak near the number four cylinder, this can cause the cylinder to misfire. If the number four cylinder's...

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...
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...
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.