49 1qe idling fluctuation.

The reason for this is the following：

1. Air, gasoline vapor and combustion waste gas that should not enter the intake manifold or various valves leak into the intake manifold, causing the mixture to be too rich or too thin and making the engine burn abnormally;

2. Too much dirt is deposited on the throttle valve and the air inlet, too much carbon dirt is deposited around the throttle valve and the air inlet, and the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle air intake, resulting in too rich or too thin mixed gas and abnormal combustion;

3. Failure of idle air actuator leads to inaccurate idle air control;

4. The air intake misalignment control unit receives an error signal and sends an error command, which leads to the engine idling air intake misalignment control. In this way, when the above situation occurs in the automobile, the cause can be found out by self-exhaust, and professionals can be invited to repair it if necessary.