What's the matter that Volkswagen Polo can't get off at idle speed after running at high speed?

The engine has serious carbon deposition, poor ignition system and unstable oil pressure.

1, serious carbon deposit in the engine: too much carbon deposit in the engine will make it difficult to start cold, the gasoline sprayed from the nozzle will be absorbed by the carbon deposit, and the mixture will be too thin, which will make it impossible to idle. Cleaning the carbon deposit at the throttle and nozzle can solve this problem.

2. The ignition system is not working well: the poor ignition conditions of the spark plug will lead to engine idling jitter, which will affect the idling decline. Check whether there is a fault in the ignition system and whether there is too much carbon deposit in the spark plug, and the problem can be solved.

3. Unstable oil pressure: the engine carbon deposit has been cleaned, the throttle has been cleaned or the spark plug has been replaced, and there is still the problem of idle jitter. Check whether the oil supply pressure and intake pressure sensors are normal.