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Q: My car will start, but will not run

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driving home on the freeway in stop and go traffic jam, car ran out of power. was able to pull over before car died. waited a couple of minutes and car started up. Made it home, but now car won't run. It starts when the key turns, but won't idle and immediately dies. it dies before I am able to press the gas to see if i can rev it. could it be the IAC, or is it a more complicated fuel issue? any way to tell at home?

My car has 190000 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 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 indicators such as engine temperature, intake air temperature and electrical system load or voltage.

As you accelerate and engine RPM increases, and then let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve. However, 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 cases where this valve is clogged or failing, your vehicle will stall instead of slowing to an idle after the release of the throttle as you have described.

I would recommend having an expert from YourMechanic come to your location to diagnose the starting issue and repair your idle air control valve as necessary.

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