What is the reason for the unstable idle speed of BMW 3 Series?

The reasons for the unstable idle speed of BMW 3 Series are: serious carbon deposition in the engine; Dirty throttle or carbon deposit in injector; Failure of spark plug, high-voltage lead and ignition coil leads to poor operation of ignition system; The oil pressure is unstable, the oil supply pressure of the oil pump is insufficient or the value of the intake pressure sensor is incorrect; Oil blockage causes insufficient oil supply; Engine parts are aging. Take the modified 320i sports suit of BMW 3 Series 202 1 as an example. The length, width and height of the car are 47 19mm, 1827mm and 1459mm respectively, and the wheelbase is 2851mm. The BMW 3 Series 202 1 modified 320i sports suit is equipped with a 2.0t turbocharged engine, with the maximum power 1 15kw and the maximum torque of 250nm, matching the 8-speed automatic manual transmission. The front suspension type is the front axle with double ball joints and spring strut, and the rear suspension type is multi-link independent suspension, load-bearing body structure and front drive mode. Million car purchase subsidy