The idling speed of the Jinbei engine with single-point EFI is unstable, and the exhaust pipe emits black smoke accompanied by rhythmic popping sound. What caused the instability? ! ! thank you

Fault symptoms: the engine surges rapidly, the exhaust smells of sulfur, and when it is serious, it emits thick black smoke, and the three-way catalyst produces high temperature or even redness!

Fault analysis: It is obvious that the engine mixture is too rich and a large amount of fuel is burned in the three-way catalyst! The most common reason for this failure is that the vacuum interface of map is blocked by carbon deposits. Map can't sense the vacuum degree of intake pipe in time and send the wrong intake pressure signal to the engine control unit.

Troubleshooting: Just pass! One more point: Finally, remove the battery head for more than 30 seconds to clear the wrong learning value of the engine control unit. It's done.