This is a MAINTENANCE case of CL125-6 electro-jet Chunlan Leopard motorcycle. Electro-jet Leopard is the earliest batch of electro-jet motorcycle produced in China. Its electro-jet system adopts open-loop control mode.

To explain briefly, the current electric spray vehicles are closed loop electric spray, the main difference between open loop and closed loop is that there is no oxygen sensor this important sensor to reflect the combustion situation.

This car has been repaired for more than 35400 kilometers. Due to valve leakage disassembly and maintenance, the engine is difficult to start and poor acceleration performance after re - assembly.

Maintenance workers have checked the oil and circuit of the electronic injection system, but no obvious problems have been found, the fault has not been eliminated, and the cause of the fault has not been identified.

After receiving the car, first check the engine valve timing and the clearance of the inlet and exhaust valve of the left and right cylinders according to the maintenance convention: Open the cylinder head cover and turn the crankshaft with a 14mm socket wrench so that the left keyway of the camshaft faces the air inlet of the left cylinder. Observe that the marking line of the timing hole of the left box cover is exactly aligned with the left line of the "TL" on the flywheel. At this time, the left line of the timing sprocket is parallel to the upper plane of the cylinder head, indicating that the timing of the air distribution is correctly installed.

Then check the inlet and exhaust valve clearance of the left and right cylinders respectively according to the "TL and TR" marking lines on the flywheel, which should be between 0.04 and 0.05mm.

Remove the spark plug, put it in the high voltage cap, and open the ignition switch to test the fire. The spark plug electrode gives out blue and white sparks and "crackling" sound, indicating that the engine ECU computer control circuit is normal.

Before installing the spark plug, try to plug the spark plug hole of the cylinder head with your finger, press the start button to rotate the crankshaft, and the finger feels the pressure in the cylinder is large, indicating that the compression pressure of the cylinder is normal.

Efi engine difficult to start, speed performance is poor failure involves the ECU electronic control system and a variety of feedback signal of the sensor and its connections, careful thought, repair the valve when ever remove the intake pipe and throttle body (including the throttle position sensor), after loading, may not according to the relevant operating procedures of the efi motorcycles to reset the body parameters, Abnormal output value of valve position sensor.

According to the steps of the fuel system fault code of the efI motorcycle, turn on the ignition switch and the ECU indicator lights up. After pressing the start button several times, the engine barely started.

After entering the running state, the ECU indicator is off. Turn off the emergency flameout switch at this time, so that the engine flameout. Short connect the two terminals of the fault diagnosis interface under the motorcycle seat cushion with special wire for 5 seconds. After the ECU indicator is on for 3 seconds and off for 3 seconds, the stored fault information is displayed.

The ECU indicator blinks for 1 long second and 3 short seconds. According to the fault code and fault contents table of the flashing ECU work indicator, the fault code is found to be No. 13, and the fault content is the throttle position sensor (open circuit) fault.

The throttle position sensor and its circuit are faulty, so that the sensor cannot perceive the throttle at the initial "0" to fully open position when it is fully closed, and the sensor function fails, resulting in disorder of the throttle position information provided by the sensor. It is necessary to check the throttle position sensor or re-insert the sensor and related circuit.

It can be seen from the throttle position working circuit of CL125-6 injector (as shown in the figure below) that the sensor is connected with the ECU by three lines. The top line is the 5V power cable that the ECU inputs to the sensor, the middle line is the signal cable that the sensor inputs to the ECU, and the bottom line is the ground line.

Use the voltage range of the high impedance digital multimeter to test the voltage between column A, B and C. When the ignition switch is ON (in the ON position), the voltage value between terminals E--A is about 5V; The voltage between C-- --A, that is, the output voltage of the throttle position sensor, will change with the throttle position.

When the throttle is in idle position (throttle closed), its voltage value should be greater than 0.5V, as the throttle slowly from idle position to full open position, its voltage value should be continuously increased; When throttle is fully open, the voltage value should be less than 4.8V.

The field test results show that when the throttle is slowly increased and the idle position is transferred to the fully open position, the voltage value does not change, indicating that the sensor is faulty. Replace the same type of sensor, and finally reset the valve body parameters according to the specified procedures.

First adjust the idle limit screw so that the valve is completely closed. Turn on the ignition again and the ECU indicator lights up. Start the engine, enter the running state after the ECU indicator light off, turn off the emergency flameout switch, the engine flameout.

Then the two terminals of the fault diagnosis interface are short-connected for 5 seconds, and the current throttle opening sensor voltage value is stored in the EEPROM as the valve body parameters. At the same time, the ECU indicator blinks steadily: on for 0.5 seconds, off for 0.5 seconds... . After four consecutive times, the electric control system works normally.

At this point, turn off the ignition switch, then turn on the ignition switch and the emergency shutdown switch, start the engine, a successful start.

Adjust the throttle adjusting screw to make the engine idle speed stable in the range of 1400±100r/min. After a little warming up, the acceleration performance of the motorcycle returned to normal, and the maximum speed reached 90Km/h.