Hafei Zhong Yi van is wheezing at idle speed, with no fault code. What's the problem?

Idle breathing, unstable. Usually it is because there is a problem with the combustion ratio in the cylinder. The common reason is that intake deviation leads to a large number of corrective measures in a short time, which will cause engine jitter, wheezing and other problems. Because the building owner's driving computer has no fault code, the intake deviation caused by the rupture of intake pipe or vacuum pipe is ruled out. The air intake system of van is usually poor in filterability. It is suggested that the landlord go to a nearby repair shop to check whether the throttle opening is too large. If it exceeds 5%, it needs to be cleaned. Then Lala's high-speed carbon emissions can basically be solved. I hope to adopt.