So when i start the car, the rpm reaches close to 3000 on startup, and then after about 3 seconds will slowly fall back down to just under 1k like its supposed to. But the real problem comes when i put the car into drive, it accelerates and decelerates normally, maintains speed perfect, but when i hit just under 10 miles an hour, the engine starts to rev and the car seems like it doesnt want to stop. when i am completely stopped, the car vibrates a lot more than usual and when i go again it jumps forward, when i put it into park the idle hits close to 3000 again and then 2 3 seconds later slowly goes back down to regular idle. i usually drive freeway speeds, and it seems like that is what triggers it. It wasnt to bad, but i just cleaned the throttle body using 3m intake cleaner, and now, when stopping, at about 3 mph, the car kicks really hard. almost like its forcing down a gear. now when i put it in park it stays at 3000 untill i restart the car. then the idle is ok
My car has 134000 miles.
My car has an automatic transmission.
Hi There, It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate. The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor. This is controlled by the car’s ECM which uses this information to make adjustments to the air/fuel ratio depending on various inputs such as outside air temperature, intake air temperature, load and various other things. As you accelerate, your car’s engine is receiving a much higher dose of fuel than when at idle and conversely, when you let off the gas pedal, there is a sudden change in this fuel supply as a result of your foot letting off the pedal. When this happens, the job of the idle air control valve is to bring this deceleration down to a slow and smooth idle rather than suddenly cutting off the fuel supply causing the motor to die. When the idle air control valve is not working properly, this cause a disruption in this process resulting in the engine not being able to idle properly. I would recommend having a professional come to your location to diagnose and inspect your vehicle.
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