Why can't Audi 100 cold car start?

Fault phenomenon An Audi 1002.2E car needs to be started quickly when it is cold, but it cannot be started immediately after the hot car is turned off. Once started, the engine will run normally.

Inspection and elimination First, the ignition system was tested, and the results showed that all parts were normal.

Then the fuel system was tested, and the measured system pressure was 370kPa, and the control pressure was 4 10 kPa, indicating that the fuel pump was working normally.

. However, according to the empirical method, the engine was started three times with the throttle fully open, and finally it was successfully started. I tried it several times, and the situation was the same. It shows that the original fault is caused by too much mixed gas when the hot car is started. Through analysis, the factors of excessive oil supply are related to fuel injectors and cold start valves. If the fuel injection quantity of the fuel injector is too large, and the abnormal operation of the engine after starting is inconsistent with the fault phenomenon, it will not be checked. The cold start valve thinks that the hot car should not work unless the control element is damaged. Unplug the cold start circuit and test it immediately. In the hot car state, the throttle is not opened up, and the engine should be easy to start and run normally. After the flameout, when the engine is turned on again, it should be easy to start and run normally. After the flameout, when the plug is connected again, the engine cannot be started again. The situation is still the same, indicating that the hot car is started and the cold start valve is still supplying oil, which is an abnormal moment to control the work of the cold start valve. Furthermore, after replacing the thermal control switch, the hot and cold cars can be easily started, all working conditions are normal, and the original fault is eliminated.

Fault analysis: the hot car cannot be started immediately after flameout. The main reason is that the thermal control switch fails, and the contact is always closed to control the cold start valve to spray too much oil when the hot car starts, which leads to the hot car not being started immediately. In addition, in order to prevent the spark plug from drowning when the cold car is started, the engine may be started successfully by controlling the cold start valve to inject at most 10s every time it is started, and sometimes it does not inject oil when it is started repeatedly.