EFI engine can not start the cause analysis and maintenance

1. Fault Cause 1) The sensor section, air flow sensor, throttle position sensor, coolant temperature sensor, speed or crankshaft position sensor are faulty. 2) Actuator part: ignition controller, electric gasoline pump or cold start injector do not work, the injector has a serious oil leakage. 3) Other parts: no oil in oil tank, low pressure in oil circuit, faulty power supply or ignition system, blockage of air filter or serious air leakage in intake pipe, low engine cylinder pressure or lockup of anti-theft system, neutral start switch output Bad signal, damaged computer. 4) limousine automatic transmission neutral start switch signal output error or engine alarm system, locked. 2. Troubleshooting 1) Check the battery connection, voltage and electrolyte density and so on. 2) Check the oil section. The hydraulic gauge connected to the pipeline between the gasoline filter and the hydraulic regulator, turn on the ignition switch to observe the pump is working; if not working, should check the fuse, pump, pump relay work is good or bad; if the work , And then observe the hydraulic conditions, if there is no hydraulic or hydraulic pressure is insufficient, it shows that there is no oil tank or oil blocked, should check the fuel, gas filters, hydraulic regulators and other working parts technical conditions. 3) Check the ignition part: Unplug the high-voltage line from the distributor cap (unplug the distributor, then directly disconnect the spark plug of the cylinder connector), so that the high-pressure line from the end of the cylinder body iron at 5 ~ 6mm, set ignition About the starting position and cranking the crankshaft, observe whether there is a strong blue spark on the high voltage terminal. If not or very weak, should check the high voltage line, ignition controller, high voltage coil, distributor, crankshaft position sensor and other components is good or bad; if there is high pressure fire, then use the same "fire" method to check each cylinder line work good Bad, check ignition timing, start injector timing switch and so on. 4) Check the car sensor: Connect the special socket hole of automobile fault diagnosis with the wire or connect it with the automobile diagnosis socket with the car special diagnostic instrument; Turn the ignition switch to "ON" position to observe the flashing law of the fault indicator lamp Manufacturers self-diagnostic test fault method is not exactly the same) to read the fault code. According to the displayed fault code, refer to the fault manual, you can detect for the corresponding components, diagnostics, find and troubleshoot (troubleshooting should eliminate code). 5) Check the actuator: check spark plug, injector is working well. The overhaul method is: Remove the flooded spark plugs for cleaning or burning on the fire (flooded spark plugs and more due to start the engine repeatedly before turning on the ignition switch or the throttle pedal in the end in order to increase fuel supply and cold start Injector caused;) If the spark plug is good, and then check the injector two terminals, turn on the ignition switch, start the engine, look at the diode stroboscopic phenomenon, if there is no strobe, check the injector and power supply, the computer Between the wiring is good, injector resistance is in line with the standard value. In addition, the fuel pipeline should also check for leaks and deformation, fuses, fuel pumps, fuel filters, fuel pressure regulators and open relay work. 6) Check the auxiliary air valve: If the auxiliary air valve is not good, check the coolant hose, air hose and cylinder compression pressure. If the cylinder compression pressure is lower than the specified value. Indicate the engine has a leak, should be dismantled engine exclusion. Check the fuses, fuses and main relays with the multimeter; check the vacuum sensor, the coolant temperature sensor, the air flow sensor, the injection signal circuit (check ECU and injector wiring). 8) Check the intake pipe for vacuum leaks, check the filter cover, oil level, hose connection, PCV hose, EGR valve continues to open.