【Fault description】
    Engine work is unstable, rapid increase, slow plus are not on the oil, and refueling when the fire back to the exhaust pipe black smoke. Adjust the ignition timing, cleaning the nozzle and gasoline filter, the fault remains the same.
    【Inspection process】
    The engine is unstable and the exhaust pipe is black smoke, indicating that the mixture is not fully combusted in the cylinder, so that the exhaust gas contains a lot of carbon monoxide, hydrocarbon and various particles, and black, rapid acceleration is more obvious. This phenomenon is caused by many reasons.
    90 Mercedes-Benz 560 car engine is used in the KE-Jetronic mechanical electronic fuel injection system, the electronic control system rarely fails, the engine failure, should first do routine inspection. First of all, should check the cylinder spark plugs are excessive carbon deposition, electrode ablation and other anomalies. If not, and then check the cylinder of the working pressure, generally should be greater than 1.2 × 1O6Pa. If the cylinder pressure is too low, the mixture will not be adequately compressed and can cause poor combustion. At this time, should check the cylinder pad, valve, piston ring, etc., to determine the reasons for leakage. If the above checks are not unusual, check the engine control system.
    The theoretical air-fuel ratio of the engine is 14.7, in the cold start, rapid acceleration or the need for high-power output, the need to enrich the mixture, the other conditions, the air-fuel ratio should maintain the theoretical value. (TPS), atmospheric pressure sensor (MAP), air flow sensor (PM), air pressure sensor (MAP), air flow sensor (MAP), air flow sensor (MAP), air flow sensor (MAP), air flow sensor (MAF), water temperature sensor (ECT), oxygen sensor and so on.
    In addition, the EGR valve (exhaust gas recirculation temperature sensor), which inhibits the NOx in the exhaust gas, is not working properly, or the three-way catalyst is also accelerated due to the long-term use of leaded gasoline.
    Check the engine electronic control system, the scanner can be inserted in the engine diagnostic socket, read the operating parameters of the various components and ECM self-diagnosis fault code. In addition, the more simple method is from the ECM connector, with an oscilloscope or high input impedance meter directly on-line measurement.