Model: BMW 318iE-D318. Engine Model: 1.18L, Jl. Transmission: FR4AT. Year of production: 1987. Driving distance: 195000km.
    Symptom: The engine can not heat up.
    Troubleshooting: The vehicle's fuel injection system is the only fuel-injected L-shaped Terra-Ronique system, which is the early product of BMW. BMW's new system, in addition to fuel injection control, but also for ignition and idling speed control, and by a computer centralized control, known as DME. It should be said that the car's control system is a rare system.
    (2) check the fuel pressure, do not start the engine when the 280KPa, the normal idle when the reference value of 220KPa, it should be said is good; ④ temperature is not good; There is no problem with the cold start ejector control when the switch is controlled. As for the compression pressure of the engine, the cold start is good, there is no problem after the start of the operation, the mechanical stability, in any case can not say hot start is not good, so also as a good look, no measurement compression pressure.
    From the above inspection results, the normal operation of the engine three elements are no problem, according to the engine should be able to start. However, the engine can not start is the fact that the three elements must have which one element is not good. There is no room for doubt; only the fuel injector only hear the sound of action, and did not see the injection of fuel, the possibility of a short injection time is very large, but the fuel is not the same, There is a need for further investigation.
    If it is fuel injection time is short, it must be warm up incremental compensation jet fuel problem, the reason is cold start no problem, and after the start of the heating machine is also no problem, the difference is only hot start compensation problem. Therefore, it is decided to start the survey with the warmer start incremental injection compensation.
    The maintenance of the reference to the BMW L-type Trinitron system wiring, the control unit has 25 terminals. Control relay terminal configuration. A oscilloscope is provided on the terminal 12 of the fuel injector to observe the fuel injection signal voltage waveform. In the warm-up can not start when the state hit the motive, the measured fuel injection time is only 2.2ms.
    Fuel injection time of 2.2ms, which is the engine after the idle operation of the fuel injection, warm up after the start of the engine, so the fuel supply is too little friends. Check the starting signal of terminal 4 at start-up, and the start signal is indeed entered into the computer.
    In the water temperature sensor signal input terminal that is, on the 10th terminal to detect the signal voltage, measured at 1.2V, although the voltage is slightly higher, but not shorten the fuel injection time factor. The water temperature sensor connector unplugged, so that the water temperature sensing floor open circuit, starting starter test, the fuel injection time extended to 5ms, the engine also started up. Although the engine started up, but the operation is very unstable, it is clear that the combustible mixture is too thick. At this time is the water temperature sensor off state, the engine idling fuel injection time could not have been so long. And then plug the water temperature connector back, the fuel injection time and shortened to 2.2ms, the engine running state recovery is good. The accelerator pedal is manipulated, and as the engine accelerates or decelerates, the fuel injection time becomes longer or shorter, and there is no problem.
    From the above inspection process and the results, consider the computer itself is bad. But for the sake of prudence, but also view the other data, the results are within the normal range. After replacing the computer, everything is back to normal.