Mine is Tiguan 1.8t four-wheel drive, and the idle speed jitter is serious. The computer detects sensors g40 and g28 and 1.2.3.

The reason that can't be ignored is "carbon deposit", which will cause insufficient combustion of gasoline and make the engine shake. The influence of engine carbon deposition on automobiles is considerable. First, the engine power is reduced, that is, the power output is uneven and gradually decays, in other words, it is getting less and less powerful. The second is to increase fuel consumption and increase your economic burden. Third, it is difficult to start a cold start, that is, it is difficult to strike a fire and it is not easy to get a taxi. Finally, serious carbon deposition in the combustion chamber will also lead to cylinder knocking, and low-speed acceleration will make noise, which will damage the piston and crankshaft, lead to engine heating, and seriously affect automobile safety. Then the discharge exceeds the standard, which not only fails the annual inspection, but also directly aggravates the harm of environmental pollution.

Another reason is that the throttle valve is out of order. The above two problems will cause engine jitter and unstable speed.