When cng vehicle is driving, the idle speed is unstable and the engine is turned off at low speed.

Engine idling flameout can be analyzed in two situations.

1, the engine shuts down automatically at idle speed.

Idle automatic flameout is mostly caused by throttle and idle motor. Serious carbon deposition or parts damage of throttle/idle motor may lead to this fault, and insufficient air intake is the main reason.

At the same time, check the air cleaner element, intake air flow sensor, intake air pressure sensor and throttle position sensor.

2. The engine can keep idling, and when idling, step on the accelerator to turn off the engine.

First, check the air intake system components, such as throttle and idle motor.

In addition, the fuel system should be considered, including whether the fuel pump is damaged, whether the oil circuit is unblocked, whether the fuel nozzle is blocked, whether the fuel pressure is normal, and so on.

The cause of this failure may also be the problem of spark plug and ignition coil. The ignition quality of spark plug is poor and the ignition coil is damaged, which can be judged by flashover experiment, but it needs the operation of professional automobile maintenance personnel, so don't try to solve it by yourself.