* Low idle speed. If your Corsa's idle speed is too low, it may not have enough power to keep the car from rolling back on hills. You can try increasing the idle speed by turning the怠速调整螺钉clockwise.
* Worn transmission. If your Corsa's transmission is worn, it may not be able to transfer power from the engine to the wheels effectively. This can cause the car to roll back on hills even if the idle speed is high enough.
* Faulty brakes. If your Corsa's brakes are faulty, they may not be able to hold the car in place on hills. This can cause the car to roll back even if the transmission is in good condition.
If you are not sure what is causing your Corsa to roll back on hills, you should take it to a qualified mechanic for diagnosis and repair.
