How to eliminate the fault of Big Dipper idling at high and low speed

The troubleshooting methods of Pacific Auto Network generally include: cleaning the throttle and air inlet, cleaning and checking the fuel injector, replacing electrical components, checking the fault point of the wiring harness, cleaning the grounding point, and repairing the mechanical structure of the engine. Most of them are related to dirty throttle. For a car with a throttle, if there is carbon deposit or other dirt at the throttle, the air intake will be reduced, or the idle valve is damaged or the computer board fails, and the air intake pipe leaks, resulting in unstable idle speed.

The leakage of intake manifold or various valves directly affects the quality of fuel mixture and combustion effect. Parts that may leak, such as intake manifold, vacuum tube, activated carbon canister valve, exhaust gas recirculation (EGR) valve and positive crankcase ventilation (PCV) valve, need to be overhauled one by one.

The instability of automobile idle speed is mainly manifested in the fluctuation and unstable pointing of the tachometer pointer at idle speed, which is often accompanied by idle jitter. In general, the idle speed of the engine is determined, and the specific level depends on the specific vehicle type adjustment. Under normal circumstances, high idle speed will lead to relatively high fuel consumption, but low idle speed will lead to engine jitter or even flameout.