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Q: Real rough idle?

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It started doing this a couple of weeks ago, it seems to be getting worse as it's going along. Doesn't seem as bad when cold and will also hesitate if going down the road and push throttle down to engage passing gear.

My car has 90000 miles.

Hi There, This may be related to a dirty or faulty idle air control valve, which is an opening in the intake that reads the air intake and relays information to the ECM which uses this information to make adjustments to the air/fuel ratio at low speeds and at idle. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your idle air control valve.

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