YC6G CNG single fuel gas engine is an internal combustion engine powered by natural gas. In the process of energy conversion, the engine will fail due to various unforeseen factors, and the common failure symptoms of electronically controlled gas injection device mainly include startup failure, insufficient power, unstable work, throttle failure, out of control and so on. The following is a brief talk about the common fault diagnosis and treatment of the electronic control gas injection device of YC6G CNG single fuel gas engine:

7. 1 The engine cannot be started.

For natural gas CNG single fuel gas engine, it is generally possible to start the engine and rotate for 3 ~ 4 revolutions, that is, it can be started. If the starter is used to drive the engine crankshaft to rotate at normal speed, although there are obvious signs of running, it cannot run with the car, or it needs to be started for many times or for a long time, or it will be turned off after starting. Can't even start.

The normal start and operation of CNG single fuel gas engine must meet five conditions: First, the battery voltage and capacity should meet the starting torque requirements of the starter. Second, the starting speed when the engine crashes should be consistent with the starting speed received by ECM, and should not be less than 200 rpm. Three, the electric control system circuit power supply is normal, the electric control components function well. Fourthly, the natural gas used meets the national CNG standard for vehicles, with smooth gas supply and good control valve function. Fifth, the related thermal protection function is not working.

The causes of fuel system failure are: the electronic controller can't provide fuel for the engine, or the electronic controller can't receive the instruction from ECM. The reasons for the failure of the ignition system are as follows: the ignition circuit does not work; Ignition coil is damaged; The spark plug is damaged. The reasons for the failure of timing system are: camshaft position sensor failure; The gap between the camshaft position sensor and the signal wheel is incorrect; The signal wheel is not installed correctly.

The first step of troubleshooting is to read the fault code with a scan tool: according to the displayed fault information, the corresponding fault location can be found and confirmed.

If there is a problem with the fuel system, the possible fault code is 1 172: the output pressure of the electronic control regulator is lower than the expected value. Or the possible fault code is 1 173: command of electric voltage regulator is lost, etc. The elimination method is: check whether there is natural gas; Check whether the valve on the pipeline is fully opened; Check whether the high and low pressure solenoid valves are open; Check whether the electric control gas supply system has electricity; Check whether there is an open circuit, virtual connection, relay or fuse in the harness circuit related to air supply, and replace the related parts if problems are found. If there is something wrong with the ignition system, check whether there is electricity in the electronic control ignition system, whether there is open circuit, virtual connection, effective relay or fuse connection between the ignition system engine and vehicle harness connector, and whether the ignition coil and spark plug work reliably. If problems are found, the relevant parts need to be replaced. If there is a problem with the timing system, the possible fault code is 336: crankshaft synchronous interference or 16: crankshaft asynchronous start. The elimination method is: check whether the voltage defined by the pin of the cam position sensor connector is correct; Detect whether that resistance value of the cam position sensor is correct; Check the clearance between the cam position sensor and the signal wheel; Check whether the installation phase of the signal wheel is correct. If it is found that the faulty parts cannot be used, they should be replaced, and the gap or installation is not in place to be adjusted. It must be noted that the clearance between the cam position sensor and the signal wheel is 0.6 0.2 mm. ..

7.2 Insufficient engine power

The so-called lack of engine power mainly means that the engine speed can't reach the calibrated speed and its torque can't reach the maximum torque index required by the operating regulations. Its main performance is that the engine is basically normal in no-load operation, slow in acceleration in load operation and weak in uphill operation. The engine is still weak after stepping on the accelerator, and the speed is not high enough to reach the rated power and maximum speed.

The causes of fuel system failure are: insufficient fuel supply; The pipeline valve failed to open in place.

The faults caused by the booster pressure control system are: the wastegate control valve is damaged; The wastegate control valve harness is damaged; The stable air pressure of wastegate control valve is too small; The inlet and outlet of wastegate control valve are wrongly connected with supercharger and stable gas source, and the exhaust port is blocked; Pipeline leaks; Insufficient intake pressure; The intercooler has poor cooling effect and enters the thermal protection state; The water temperature in the engine cooling system is too high, so thermal protection works.

Causes of failure of ignition system: poor wiring connection and non-working spark plug; The ignition coil is damaged.

Causes of failure of exhaust system: failure of three-way catalyst; Exhaust blockage.

Troubleshooting: First read the fault code with a scan tool: you can find the corresponding fault location according to the displayed fault information. Confirm the fault location.

If there is a problem with the fuel system, the possible fault code is 1 172: the output pressure of the electronic control regulator is lower than the expected value. Or the possible fault code is 1 173: command of electric voltage regulator is lost, etc.

Elimination method: check whether there is natural gas, which is not enough to add fuel; Check whether the valve switch on the pipeline is flexible, and make adjustment and maintenance to realize effective action coordination function; Check whether the high and low pressure solenoid valves are stuck, and judge the operation of the solenoid valves by on-off method; Check the gas leakage position of the gas supply pipeline with a gas leakage diagnostic instrument and eliminate it; When the electronic throttle is turned on, cleaning and maintenance will be reliable and sensitive.

If there is a problem with the intake pressurization system and the intake pressure is insufficient, the possible fault code is 1 1 1, and the intake air temperature is high; Or 1 16, the engine water temperature is high; If there is air leakage in the pipeline, the possible fault codes are 234 throttle inlet pressure (TIP) higher than the boost setting or 299TIP lower than the boost setting 3pai. The regulated air supply pressure provided to the wastegate valve is not within the technical requirements: the possible fault code is1131:the WGP power supply is higher than 4.7V, or the possible fault code is1132: the WGP power supply is lower than 0.2V 。

Troubleshooting: check the vehicle cooling system and clean the intercooler; Check the connection between engine harness and water temperature sensor; Replace the corresponding faulty parts. Check the tightness of the intake pipe; Check whether the diaphragm of the anti-surge valve is broken, and pay attention to adjust the stable air supply pressure of the wastegate valve to the technical requirement value of 23.5psi.

If there is something wrong with the ignition system, troubleshooting methods: check the ignition coil; Whether the rubber sleeve of ignition coil is aged or damaged. Check whether the performance of the spark plug is normal, and replace it if it is damaged. It must be noted that the spark plug electrode gap is 0.33 mm, too large or too small will affect the ignition performance of the spark plug.

If there is something wrong with the sensor, the possible fault code is 108: high intake pressure (MAP) voltage after throttle; Or 107: map voltage is low. Or the possible fault code is 236: the throttle inlet pressure (TIP) is not working properly; Or 237: tip voltage is low; Or 238: Tip voltage is high.

Troubleshooting: Measure the output terminal voltage and sensor resistance according to the definition of the corresponding sensor pin. If there is a fault, replace the corresponding sensor; Check the wiring harness; Check whether the connection between the harness and the sensor is reliable and effective.

If there is a problem with the exhaust system, troubleshooting method: check whether the three-way catalyst is invalid. After the fault, the exhaust will be blocked and the engine running resistance will increase. Replace the failed three-way catalytic converter.

7.3 The engine is unstable.

When the engine is idling after landing, the speed cannot be stabilized within the technical requirements of 600 ~ 700/min (700 rpm for cold car and 600 rpm for hot car), or the speed is unstable at high speed, and it swings greatly in the range of high speed and medium speed.

The causes of fuel system failure are: insufficient fuel supply; The valve in the pipeline is not opened properly, the filter is blocked, and the gas circulation is not smooth or leaking.

The causes of ignition system failure are: poor contact of ignition circuit connector; Individual ignition coils leak electricity; The gap of individual spark plugs is too large, which leads to fire, side breakdown and damage.

The reasons for the failure of the timing system are: the gap between the camshaft position sensor and the signal wheel is too large, which makes the signal collected by the camshaft position sensor partially lost.

The reasons for the failure of the related sensors are: a sensor of the throttle intake pressure sensor (MAP)/ intake pressure temperature sensor (MAT) is faulty or works abnormally.

Troubleshooting: first read the fault code with a scan tool: you can find the corresponding fault location according to the displayed fault information. Confirm the fault location. If there is a problem with the fuel system, troubleshooting methods: check the fuel shortage; Clean or replace the filter. Check the tightness of the air inlet pipeline, check the air leakage position of the air supply pipeline with the air leakage diagnosis instrument and eliminate it; Check whether the diaphragm of the anti-surge valve is broken. If it is damaged, please replace it. If there is a problem with the ignition system, troubleshooting methods: check that the ignition circuit is in good contact with the connector; Check the replacement or faulty ignition coil; Check the spark plug: clean the oxide, adjust the excessive gap, and replace it if it is damaged due to breakdown. If there is a problem with the timing system, the troubleshooting method: check and adjust the gap between the camshaft position sensor and the signal wheel to meet the technical requirements. If there is a problem with the related sensor, troubleshooting method: After measuring the throttle intake pressure sensor (MAP)/ intake pressure temperature sensor (MAT), check the technical value of the throttle intake pressure sensor (TIP) and replace the sensor that failed to transmit.

7.4 The computer and ECM cannot communicate.

When the engine working state is detected by the computer diagnostic instrument, after the diagnostic computer is connected with the communication diagnostic interface of ECM, the computer diagnostic page is opened, and it is impossible to browse the fault information, download the fault data and read the fault code, and the dialogue between the diagnostic computer screen and the engine ECM is not displayed.

Troubleshooting: Check whether all circuits are connected correctly, and use digital multimeter to find out the open circuit and whether the circuit connection is reliable. Whether the ECM connector is separated and connected in place; Check whether the communication port connector of vehicle wiring harness is connected correctly, and correct it if there is any error: check whether the defined voltage of the diagnostic communication interface pin of ECM is correct; Correct the wrong connection of communication lines. If necessary, replace the communication line or ECM or engine harness; Disconnect the power supply of strong electromagnetic components. Note the definition of diagnostic interface pins: 4 wires. The output voltage A is 4.5V, B and C are 5V, and D is grounded.

7.5 Throttle fault

When the car is running with the engine on, the engine speed cannot be increased with the driver's wishes when stepping on the accelerator, but the engine speed is only fixed within 800 rpm. The possible fault code is 2 123: electronic throttle harness error; Related lines are open and short-circuited, and the lines are not connected; The accelerator pedal cannot be fully opened or damaged.

Troubleshooting: Check the circuit according to the circuit diagram, find out the open circuit with a digital multimeter, and connect the circuit reliably. Check the terminal voltage and line connection according to the definition of accelerator pedal pin, correct the wrong line, connect the connector in place, and replace the accelerator pedal if necessary.

7.6 speeding (speeding)

When the engine is on or running, the engine speed cannot run according to the driver's wishes and is out of control. The engine speed suddenly rises and exceeds the maximum allowable speed, and the engine makes a lot of noise. Running away from home is extremely dangerous. If effective measures cannot be taken in time to stop it, the engine will eventually be seriously damaged.

The reasons for the failure of the fuel system are: the command of the electronic control voltage regulator is lost; The fuel entering the electronic pressure regulator is not controlled by ECM and enters the cylinder.

Troubleshooting: read the fault code with a scan tool: you can find the corresponding fault location according to the displayed fault information. Confirm the fault location. If there is a problem with the fuel system, the possible fault code is 1 173: the command of the electric pressure regulator is lost or there is no fault code. Troubleshooting method: check whether the circuit of the electric control voltage regulator is open, find out the open circuit with a digital multimeter, and connect the circuit reliably. Whether the connector of the electric voltage regulator falls off and connects the connector in place; Replace the damaged voltage regulator. 8. Maintenance skills: ① Use the fault diagnosis system to determine the fault location: YC6G CNG single fuel gas engine has a random fault self-diagnosis system and a special diagnostic interface, which provides some help for fault diagnosis. The fault self-diagnosis system notifies the fault through the fault indicator lamp and the fault diagnosis request switch. When the engine fails, the indicator light flashes to remind the driver to carry out maintenance. The fault indicator light is generally installed on the instrument panel and connected to the controller through the vehicle connector. In order to determine the fault location, the maintenance personnel or the driver can turn on the diagnosis request switch, and the fault light will output the fault flashing code at a certain flashing frequency. You can read the fault flash code and consult the fault manual to understand the fault types and treatment methods of the engine. If necessary, connect the computer diagnostic instrument, read the fault code, collect data and analyze the data, so as to find the fault point quickly.

(2) When the fuel supply system composed of various control valves breaks down and a control valve needs to be repaired or replaced, attention must be paid to depressurizing the fuel supply system before the repair and replacement, so as to avoid the impact of air pressure and environmental pollution in operation and ensure property safety. This method is simple and feasible. The specific operation is to turn off the main switch of the gas supply source of the gas cylinder and start the car. When the natural gas stored in the gas supply pipeline is burned, the engine will automatically turn off. Then turn off the ignition switch and disconnect the battery power supply circuit, so as to carry out maintenance or replacement operation.

③ Inspection of ③CNG gas path: One of the prerequisites for starting the engine is that the pressure of natural gas entering the cylinder must reach the working pressure, and the engine cannot be started without gas fuel. Simple inspection of external air leakage: first, turn on the main switch of natural gas source, turn on the ignition switch, observe and record the capacity value of the gas indicator on the dashboard of the cab, turn off the ignition switch for about 5 ~ 10 minutes, then turn on the ignition switch, and check again whether the capacity value of the gas indicator has changed from that before turning off. If yes, if the value drops, it means that there is a leaking part, and the leaking part can be quickly found and eliminated by the leakage diagnosis instrument. Judge whether the fuel natural gas pipeline is supplying gas normally, loosen the rubber hose clamp at the natural gas inlet of the mixer, disconnect the pipeline from the joint, and plug it at the joint by hand. At this time, when the motor is started, the hand can feel a gas jet, indicating that the gas pipeline flows normally. On the other hand, to find the position where the gas path is not smooth, we can investigate it according to the step-by-step inspection method of CNG engine gas path direction.

(4) It is forbidden to pull and insert inductive elements with electricity to avoid burning out the electric control elements. There is something wrong with the ignition system. When the engine is working, don't touch the exposed part outside the ignition coil with your hands, so as not to hurt people by high-voltage electricity. Natural gas engine adopts independent ignition mode, and each cylinder is controlled by an ignition coil. When the engine is working, judge whether the ignition coil is working normally. If the ignition coil leaks electricity, it will make a "squeaky" discharge sound. It is easy to observe whether there is intermittent spark leakage in the ignition coil when the light is dark. Unplug the external plug supplied by the cylinder ignition coil by hand, and observe the engine speed by power-off method. If the speed drops, it means that the cylinder is working, otherwise it means that there is something wrong with the cylinder. Quickly judge, observe the ignition waveform and test the working condition of the cylinder with a computer diagnostic instrument. Note: the cylinder breaking method cannot be used for too long to avoid poisoning and damage to the oxygen sensor.

⑤ When the controller (ECM) has been installed on the vehicle body and connected with the wiring harness, it is forbidden to conduct electric welding on the vehicle body! Otherwise, electronic control components such as ECM will be burned. If welding operation is needed on the car body, be sure to turn off the main power supply and disconnect the harness of the controller.

⑥ It is forbidden to clean the engine and electronic control components with high-pressure water gun, so as to avoid leakage, corrosion, open circuit and short circuit of electrical connectors, and the electronic control gas injection system cannot work normally. Be sure to keep all components of the electronically controlled gas injection system clean and dry.

⑦ When the engine is working, do not disconnect any wires of the battery at will. The structure of the battery itself is equivalent to a large capacitor, which is connected in parallel with the load and the generator, so it can absorb the surge voltage generated at the moment when the inductive load is turned on and off, and protect the electronic components such as ECM on the vehicle. If the battery power is insufficient, the starter can't drive the engine to rotate or it is difficult to start. Don't start the engine when the external power supply is connected in series with the vehicle power supply, so as to avoid burning out the electrical equipment and electronic control components of the vehicle due to excessive power supply voltage.

The above briefly introduces the faults and troubleshooting methods of electronic control gas injection device of YC6G CNG single fuel gas engine, which is only for the reference of peers in maintenance work. Criticism and correction of irregularities.