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Q: When the rover is cold, the idle is steady, but when it gets cold, the idle changes. I have to keep my foot on the gas and brake

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When the rover is cold, the idle is steady, but when it gets cold, the idle changes. I have to keep my foot on the gas and brake or else the Rover will die

My car has 135000 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. I'd be happy...

Hi, thanks for writing in. I'd be happy to help.

This is a case of an idle air control valve not working properly. An idle air control valve literally bypasses air around a closed throttle plate so the engine can get air at idle. Because it bypasses air, it’s also called an air bypass valve. On start-up, the engine control module (ECM) or powertrain control module (PCM) checks engine coolant temperature, ambient air temperature, barometric pressure (on some engines) and then determines how much air and gas is required to start the engine. The idle air control valve works at idle and during deceleration-- in other words, any time you take your foot off the pedal. During deceleration, the computers on most fuel injected vehicles perform a “fuel cut” procedure where the the fuel injectors are forced to cut fuel to the engine resulting in RPM drop. However, since the pistons are still moving up and down, the engine still needs an air supply. The idle air control valve opens during deceleration to provide that air. This appears to be the problem you are experiencing.

If you would like help resolving this idling issue, consider having an expert automotive technician from YourMechanic come to your home or office to inspect your vehicle for you, and make any repairs as needed.

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