What should I do if Mazda 3 cool car starts noisily?

As for the problem of unstable idle speed of cold car, it may be caused by excessive carbon deposition in intake, intake valve and combustion chamber. You should not only check and clean the throttle, idle motor and fuel injector; Also check the air inlet, because there is too much carbon and dirt accumulated in the air inlet and the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake air volume, which leads to the mixture being too rich or too thin, and the low temperature in recent morning leads to poor atomization of the mixture, which leads to abnormal combustion or engine jitter after starting. At the same time, check whether the spark plug has too much carbon deposit. What's more, the noise problem of the cold car you mentioned should be caused by the poor lubrication of the engine due to the high viscosity of the engine at low temperature. I hope my answer is helpful to you.

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