Hi, my car has n very rough idle and lack of power, but only on warm days. Why is this not happening on cold days?
My car has 90000 miles.
My car has an automatic transmission.
This problem may be caused by a coolant temperature sensor, idle air control valve, throttle position sensor, or O2 sensor that may be failing. Use a digital volt ohm meter (DVOM) to check resistance on all of the sensors. If a sensor has no resistance, it is a sign that it has failed. Check the harness plugs for any debris, moisture, oil, bent pins, or broken wires.
If you need further assistance, then seek out a certified technician, such as one from Your Mechanic, to check and replace the coolant temperature sensor, idle air control valve, throttle position sensor, or O2 sensor that is faulty.