It is difficult to start the old Jetta cold car, but what is the problem with the hot car?

It is because too much carbon deposit on the accelerator causes the engine to be unstable at idle speed, easy to stall and difficult to start, as well as too much carbon deposit and dirt in the surrounding intake port and the change of the cross-sectional area of the intake port, which makes the control unit unable to accurately control the idle intake air volume, resulting in the mixture being too rich or too lean, which leads to abnormal combustion or engine jitter or even failure to start after starting. At the same time, check the working state of the fuel injector, so it is recommended that you clean: 1 and excessive carbon deposit inside the engine. 2, check the gasoline pump oil pressure is too low. 3. Check whether there is leakage in the fuel injector. 4. Clean the throttle and idle motor. Check and repair according to the above five points. At the same time, it is best to check the carbon deposit with an endoscope at a conditional service station. According to the above investigation, this kind of fault is not an incurable disease in regular 4s shops.

I don't know the age of the old Jetta.

Since Jetta entered the China market, there are new varieties of carburetor and EFI besides electric pump.

Generally speaking, however, it is difficult to start a hot car because the mixture is too thick or ECU misjudges the mixture ratio.

Water temperature sensor, crankshaft sensor and oxygen sensor may all fail. The carburetor nozzle drips oil, and the activated carbon canister switch fails, which makes it difficult to start the hot car. The most wonderful thing is that the fuse is not fixed properly. When the car is hot, it gets stuck on the valve cover and short-circuits. When it is cold, it doesn't play anything.

So go to the repair shop and let the master check them one by one.