Has been an off and on problem for years. As I slow down with my foot off the gas, my RPM's drop super low, sometimes the car dies, sometimes the RPM goes back up to a steady idle. Just cleaned the battery posts and cables. Didn't fix the problem this time, but that seems to have worked a few years ago. Checked the connections to my alternator and they seem solid.
My car has 130000 miles.
My car has an automatic transmission.
Idle Control Valve Replacement | $162.54 - $1028.01 | Get a Quote |
What you are describing sounds like 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 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 inspect your vehicle.
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