1. The car anti-theft system is triggered, locking the engine, so that the engine can start but cannot run. Release the key and it will turn off after one or two clicks, and the anti-theft light will turn on.
This situation usually occurs in Volkswagen Audi cars. Most of the time, it is because the owner privately matches the key without a chip to prevent the key from being lost, or the key is knocked and the signal is weakened, so the system cannot recognize it. Another reason is that the engine computer or anti-theft system components are not matched after replacement, and the circuit is damaged.
2. Ignition switch failure. There is electricity in the ignition wire when starting, but the power is cut off when the key is released, and the engine suddenly shuts down.
This situation is generally caused by poor contact of the internal contacts of the ignition switch, and is mostly accompanied by the fact that the dashboard battery light, oil light, and engine fault light are not on. Some have intermittent faults such as no air conditioning and heating, no headlights, and malfunction of electric doors and windows for a period of time before the failure.
3. The ignition module is damaged or the ignition reference signal line from the ignition module to the engine computer is damaged.
This situation is common in American cars, especially Buick cars (the few cases I repaired are Buick cars, including the old Regal and the New Century). It is incomprehensible - the ignition module is broken, why can the car start when it is started? This is related to the control method of the Buick ignition system. If you understand its special features, it is easy to understand. Simply put, when the engine speed is lower than 500r/min at the beginning of the start, the ignition module controls the ignition according to the crankshaft and camshaft position sensor signals and its internal inherent data. When the engine speed is higher than 500r/min after starting, the ignition control and injection control are transferred to the engine computer, and the engine computer performs comprehensive control according to various sensor signals and the ignition reference signal sent by the ignition module.
4. The fuel system pressure is too low, such as low fuel pump pressure, pipeline leakage, low power supply current, damaged fuel pressure regulator, etc.
.When the fuel system pressure is too low, the gasoline sprayed during the normal injection time is too little, and the mixed gas formed cannot be compressed and ignited. However, during the start, the injection time corrected by the start program is greatly extended. Although the fuel system pressure is too low, the injected gasoline can be compressed and ignited, and the engine can be started. Once the normal injection is transferred after starting, the flameout occurs. In addition, the fuel pump does not pump oil. In the first dozen or so starts, this phenomenon also occurs - it can be started, but it immediately stalls after starting.
