Does Buick Hideo's cold start jitter and unstable idle speed have anything to do with the timing belt?

Buick Hideo's cold start jitter and unstable idle speed are all related to the timing belt. In general, if the cold car starts to tremble at idle speed and the hot car does not tremble, it is best to clean the throttle at this time. If both the cold car and the hot car are shaking, and the more severe the thermal shaking is, the acceleration is not smooth, so it is necessary to check the spark plug and ignition coil.

It's no big deal that the idle speed is slightly shaken, but if it is serious, it must be checked to make sure that the engine is faulty. Slight jitter, generally speaking, is that individual cylinders do not work very well. If multiple cylinders don't work well, they will definitely shake badly, even without idling.

Causes of unstable idle speed

When air, gasoline vapor and combustion waste gas that should not enter enter the intake manifold, the mixture is too rich or too thin, which makes the engine burn abnormally. When the air leakage position only affects individual cylinders, the engine will shake violently, which has a great influence on the idle speed of cold cars. Common causes are: loose clamp of intake manifold or broken hose.

Air leakage of intake manifold gasket; The intake manifold is damaged or other parts grind holes in the intake manifold; O-ring of fuel injector leaks; Vacuum tube plug falls off and breaks; The positive crankcase ventilation (PCV) valve has a large opening; The valve of activated carbon tank is normally open; Exhaust gas recirculation (EGR) valve is not closed correctly.

There is too much carbon and dirt in the throttle and the surrounding air intake, and the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake, resulting in the mixture being too rich or too thin, which makes the combustion abnormal. Common reasons are: the throttle has oil pollution or carbon deposition; There are oil stains and carbon deposits at the air inlet around the throttle; Idle stepper motor, duty solenoid valve and rotary solenoid valve are polluted by oil and carbon.