What's the matter that the idle speed can't come down?

It may be mainly caused by excessive carbon deposition in throttle, air intake, air intake valve and combustion chamber. Due to too much carbon and dirt in the air inlet, the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake air volume, resulting in too rich or too thin air mixture, abnormal combustion or engine jitter, and even unable to start after starting.

At the same time, it is also necessary to check the working state of the fuel injector to see if the pulse width of the fuel injection is up to standard. Also use an endoscope to check whether there is too much carbon deposition in the intake valve and combustion chamber. Check the throttle idle motor, check the spark plug, check the coil and cylinder line to see if there is a lack of cylinder.

Extended data:

The reasons for the high engine speed are as follows:

(1) Air leakage in the engine air intake system: it has been repaired through maintenance, and the cause of the problem has been eliminated;

(2) Engine exhaust pressure regulating valve is damaged: it has been repaired through maintenance, and the cause of the problem has been eliminated;

(3) Need to increase the speed: for example, heating the seat or turning on the air conditioner;

(4) Insufficient battery charging voltage: The battery manager can increase the power generation by increasing the engine speed.

References:

Idle speed _ Baidu Encyclopedia