Chang 'an Suzuki Tianyu sx4 cold car rattled and tempered at idle speed, and the exhaust pipe made a slight noise. It is possible that the air flowmeter was replaced and the VVT valve was cleaned.

The causes of idling jitter of cold car are: 1 engine mechanical failure, such as uneven pressure in each cylinder; 2 air intake system failure, such as air leakage in the air intake pipe; Excessive carbon deposition in the intake valve and intake pipe, excessive dirt on the inner wall of throttle valve and intake pipe, etc. 3 engine management system failure, such as incorrect water temperature and intake temperature signals, line failure, etc. ; There is something wrong with the ignition system, such as excessive carbon deposition on the spark plug or incorrect gap, leakage of high-voltage line and distributor cover, and damage to the ignition coil. ⑤ The oil supply system is faulty, such as the nozzle is not closed properly or blocked due to excessive colloidal carbon deposition in the nozzle.