BMW mini B38 engine, the reverse gear of cold car has serious jitter.

1, the oil circuit is not smooth, and the engine oil can't keep up with the low throttle, resulting in uneven operation and jitter of each cylinder of the engine.

2. The throttle valve is too dirty, and uneven intake leads to jitter.

3. The high-voltage line is broken and burned out, or the spark plug is broken, the cylinder does not work, and the engine is unstable and wobbly.