Chery cars vain Failure Analysis and Troubleshooting

         Symptom: Starter can work, but vain car. The car was in the car repair shop, Chery single point EFI.
         Check: First, starter able to work without a car, you can follow the car a prerequisite to maintenance. The car's gasoline prerequisite is that a cylinder pressure enough; two, ignition and ignition timing normal; three-cylinder mixture concentration standards. After investigation, the car enough cylinder pressure, fuel injectors in starting work and will fuel injection, while sub-cylinder line does not flash. The reason is not vain car flash. So check the cause can not flash. Car Boshi WU-2000B obtain obd2 code scanner fault codes. There are three historical fault codes, namely: the battery voltage is too low, the fuel injector is not working, speed sensor failure. But after clearing the fault code system normal, no fault, and car components Boshi WU-2000B for action test, sub-cylinder line can flash, action testing other components are normal; That electronic control unit and the system is normal . The car should be to regroup.
         The car vain because the sub-cylinder car line does not flash. The ignition control system for the electronic control unit (commonly known as the computer board), and then check the car Boshi WU-2000B no fault codes; component actuation test can flash over, it seems normal. Therefore can not blindly break a dead end. Technically trouble, leaving a shortfall of a link, that inquiry. Thus, the original repair shop maintenance personnel recruited, this car was originally entered the repair shop, and when changing the gearbox casing, the speed sensor wire dial off, get a new sensor. We also focus on checking the speed sensor. The sensor for electromagnetic induction sensors. When the search operation by the starter, there is an induced voltage. No fault code. When dialing this speed sensor, when the re-start, the fuel injection nozzle is not. Therefore, the speed sensor can determine the work. This also in trouble. Is the computer board is damaged. The car is moved Digimaster III into the factory to the computer board should not be damaged. So we carefully analyzed, Chery single point EFI works. The system is Marelli produced I, A, W, 6F single-point fuel injection system. The system has no camshaft sensor, only one speed sensor, the sensor is fixed to the front of the transmission housing. Provide speed signal for ECU, while providing sub-cylinder signal. Because of the hands-free oscilloscope, waveform failed to see the speed sensor. Thus, the replacement of a speed sensor, and sure enough, that is the car moving along. At this point the problem is solved.
          Analysis of reasons: a single point Marelli EFI system. Provided by the speed sensor and the speed signal while the signal point of the sub-cylinder top dead center, due to poor sensor performance, to provide a speed signal (the signal estimated to have bad), and therefore, fuel injectors to work, the system is no fault code. But it can not determine the dead, the ECU does not cause ignition, but not the car. A gotcha shoddy sensor.
http://www.obdnews.com/index.php/benz-diagnostic-tool/