What is the reason for the unstable idle speed of Alto hot car?

The initial judgment should be that the throttle position sensor or related circuit is out of order, resulting in the ECU not knowing whether it is idling or not and not adjusting according to the target speed. There are many reasons for unstable idle speed, which are too high or too low, but they are basically caused by oxygen sensors, throttles and air flow meters. The failure of water temperature sensor sometimes leads to high idle speed. At the same time, check and adjust whether the ignition time is premature.

First of all, check the working performance of the spark plug. The initial judgment should be that the throttle position sensor is not working properly or the plug on the sensor line is dirty, resulting in signal distortion. Then, it is judged whether the idle motor is stuck due to excessive carbon deposition, and the intake pressure sensor and related lines are faulty, resulting in ECU not knowing whether it is in idle state and unable to adjust according to the target speed. Idle speed is unstable, too high or too low. At the same time, check whether the ignition time of air filter and valve is adjusted too early. At the same time, check whether the throttle is too dirty and the starting voltage of the battery.