Q: Q: Why is my car idling high

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My car was running hot so I got a street mechanic to change the radiator when I came back my car was idling high and he said he didn't know why so I took my car home I change the mass air flow sensor checked for a vacuum leak and also change my throttle position sensor yesterday and clean everything and it's still doing the same thing also I noticed my car is leaking coolant it wasn't doing that when I took it to the mechanic I was thinking maybe he didn't hook up all the wires but idk I have had a handful of mechanics look at it and tell me different problems but I fixed it all and it's still has a high idle of 3

My car has 186000 miles.
My car has an automatic transmission.

This may be related to a faulty idle air control valve or possibly a throttle stop that may need to be adjusted. 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 and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. 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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