A Mercedes C280 car with a mileage of about 140 thousand km and a M112 engine and automatic transmission equipped with W202. Users reflect: the engine of the car is unable to accelerate, and the speed of the throttle close to full opening exceeds 30km/h, and the malfunction usually occurs after stopping or accelerating. After receiving the vehicle: connect the diagnostic instrument for self diagnosis, and the engine system has no fault code. Road test, when the fault appears to look at the data flow, idle speed and acceleration under the ignition advance angle of -6 to 2 degrees. The ignition switch is closed, the engine is restarted, the acceleration test is carried out, the fault is disappeared, the ignition advance angle is observed at this time, the idle speed is 5.5 degrees, and the acceleration condition reaches more than 40 degrees. The above test results show that the ignition advance angle control function and fuel control function are intermittent failure. From the engine fuel injection principle, the engine control module controls the ignition advance angle according to the deflagration sensor, the coolant temperature sensor, the intake temperature sensor, the crankshaft speed sensor, the air flow sensor and so on. Therefore, it is necessary to focus on these sensors, and the actual inspection results, these sensors are all normal. Check the engine control module and find no obvious abnormality. Replacement processing, road test, failure symptoms disappear, maintenance work ended. This case vehicle is relatively rare. During the maintenance process, we should pay attention to the relevant sensor signals, ignition advance angle data and fuel injection data. If the sensor signal is normal, the performance of the engine control module can be judged to be poor.