Reasons for unstable engine idle speed
In the idle performance of diesel engine, the stability performance is a relatively important indicator. The reasons for the instability of the idle speed of the diesel engine are as follows:
(1) When the idling speed is large, the air leakage of the cylinder is large, and the energy loss in the cylinder is high, so that the compression temperature and pressure are low, the fuel atomization is not good, and the combustion fluctuation is large;
(2) When the oil supply is small at the time of idling, a small change in the oil supply amount of each cylinder will result in a different working state of each cylinder. The uneven oil supply of each cylinder during this idling will lead to the idle speed of the diesel engine;
(3) The direct injection of diesel engine makes the injection pressure develop to high pressure, especially the use of porous injector, which makes the nozzle less accurate and less volatile when providing small oil quantity. The instability of diesel engine oil supply leads to idle speed. An important reason for stability;
(4) The use time of the fuel injection system increases and the aging of the fuel injection system causes differences in the fuel injectors and the oil discharge valve of each cylinder, resulting in further unevenness of the oil quantity, which increases the fluctuation of the idle speed.