Why is Liberty running at 4000 revolutions?

When the engine is idling, the speed is too high, which will increase fuel consumption and noise. Excessive idle speed is mainly caused by excessive air intake, excessive fuel injection or incorrect engine control signal. The inspection process is as follows:

1) Check the vacuum tube for air leakage. If there is a vacuum leak, the ECM may increase the fuel injection quantity, resulting in excessive idle speed.

2) Check whether the idle speed control valve works normally. Whether there is carbon deposit stuck and whether the valve body is in good condition.

3) Check whether the throttle valve is closed at idle speed. If it is not closed properly, check whether the throttle is stuck due to carbon deposition or the throttle is locked too tightly.

4) Check whether the signals of air temperature sensor and water temperature sensor and their circuits are normal. If the detected temperature is higher than the actual temperature of the engine, fuel injection will increase, resulting in high idle speed.

5) Check whether the signal of air flow meter (or intake manifold pressure sensor) and its circuit are normal.

6) Check whether there are signal output or wiring problems when the air conditioning system, power steering switch and shift switch are not working. If these systems still output signals when they are not working, the idle speed will be too high.

7) Check whether there is any problem with the engine control module or matching setting, and reset it if there is any problem.

8) Check whether the fuel pressure is too high. If the pressure is too high, the fuel injection quantity will increase, and the idle speed will be too high.

9) Check whether the fuel injector leaks. If the fuel injector leaks oil, it will increase the fuel injection quantity and make the idle speed too high.

10) Check whether the fuel injection quantity of the fuel injector is within the specified range.

It is recommended to go to 4S inspection.