First, this article mainly introduces a photoelectric ignition engine, which causes the failure of the central high voltage line not to jump because of the bad line contact, and analyzes the causes and detection methods of the fault from the components that make up the ignition system. Two. Preface photoelectricity contactless electronic ignition system is a circuit which is replaced by photoelectric ignition control instead of contact ignition. The fault is usually caused by the fault of sensor, vehicle computer, low voltage circuit and high voltage circuit. Once the fault occurs, the engine work is not normal or even can not be started. Because it is completely electronic control, the circuit is complex, the technology is strong, and the fault is hidden, it is difficult to find. Therefore, the analysis and study of the ignition system The method of composition and fault detection has a certain reference significance for myself and related maintenance personnel, to improve the technical level of maintenance and to eliminate automobile failures accurately and quickly. Three, the main body (1) the ignition system of electronic control engine ignition system ignition system of the central high voltage line does not jump fire, mainly there are three aspects: (1) low voltage circuit fault, that is, from the ignition switch to the high voltage coil primary end of the circuit fault. 2. The breakdown of the high voltage circuit, that is, the breakdown from the central high voltage line to the spark plug section. 3. Electronic control circuit, that is, photoelectric sensor, computer, power transistor igniter, etc. (two) the composition of the ignition system and the cause of failure, including the electronic control ignition system, including the crankshaft position sensor and the electronic controller, and according to the working order of the engine and the requirements of the ignition time, timely and accurately send the high voltage electricity to the spark plug of each cylinder, produce the electric spark and ignite the combustible mixture, so as to make the start of the ignition. The machine works. The reasons for the failure of the high voltage and non jump fire of the engine are as follows: 1. the high voltage coil is connected to the high voltage coil at one end and the other end is connected to the power amplifier in the igniter. When the power transistor is connected, the primary winding is electrified and the magnetic field is generated. When the power transistor is cut off, the secondary winding sense is cut off. High voltage leads to spark plugs jumping, such as short circuit or open circuit of high voltage coil, which can not reach 10 ~ 30kV high voltage, that is, not jump fire. 2. photoelectric crankshaft position sensor out of fault six swordsman Vocational Education Park (the largest free teaching resource website) photoelectric crankshaft position sensor composed of light emitting diode, photosensitive triode, CD-ROM and signal processing circuit, installed in the distributor. The ratio of the speed of the camshaft to the speed of the crankshaft is 1:2, and there are 360 leaky joints or holes carved on the disc, which are used to generate the camshaft signal with 1. corners. Inside the outer edge, there are 6 light holes whose spacing is 60., which is used to generate 60. camshaft angle signals, also known as 120. crankshaft angle signals. With each rotation of the camshaft, the sensor outputs two optoelectronic conversion pulses, of which 360 1. cam angles are used as signals or speed signals of the crankshaft angle 2., called Ne signals. ECU determines the engine crankshaft angle or engine speed by detecting the Ne signal. The other 6 120. crankshaft angle signals are called cylinder signals of the six cylinder engine, which are called G signals. ECU determines the ignition time of the piston top stop by detecting the G signal. Based on the ECU and G signals, the IGT signal is sent out to the power transistor igniter to control the primary current of the ignition coil and to control the ignition. If any damage or breakdown in the transistor (light emitting tube or photosensitive tube) in the sensor, or failure of sensor joint contact, failure, power supply and other failures, the axis position sensor will affect the transmission of Ne or G signals to the computer so that the high pressure of the engine can not jump. 3. engine ECU has a failure engine ECU to receive G and Ne signals from the crankshaft position sensor, and send a IGT ignition signal to the power transistor igniter. If an integrated block, CPU, memory, ADC, and interface are damaged or loosed in the electronic computer, all the ignition signals can not be sent to the power tube. The G and Ne signals from the crankshaft position sensor can not be received. The 4. power transistor igniter has the breakdown transistor igniter breakdown or failure, and can not send the ignition voltage to the primary winding of the high voltage coil, so that the high voltage ignition coil can not induce the high voltage power. The safety signal resistance feedback the collector voltage variation of the power transistor to ECU. When the power tube fails, the terminal voltage of the safety resistor will also change. ECU interrupts the fuel injection of the cylinder according to the change of the voltage. (three) the fault detection of the components of the ignition system 1. ignition coil detecting the resistance value of the winding of the ignition coil by the multimeter ohm gear, the initial standard of the resistance value of the coil, such as Japan, Ford, and TOYOTA, is as follows: (if the requirement is not required), the 2. crankshaft position sensor will check the position of the crankshaft. The wire of the sensor connects the plug. When the engine is rotated, the digital multimeter voltage gear is used to detect the crankshaft position sensor G and Ne terminals to check whether there is a pulse voltage (if there is no need to replace the sensor). 3. the detection of the power transistor igniter. The multimeter only uses the X1k shift to measure the positive and negative resistance values of the power tube. The resistance should be in accordance with the regulations. If the resistance is positive or negative, it indicates that the power tube is damaged or failed. 4. the detection of spark plug is used to measure the spark plug insulation resistance of the multimeter ohm. The ignition fault is sometimes not produced according to a certain rule, such as the short circuit, or circuit breakage, variable value and so on in the system. It will deviate from the detection thinking and often occur in the neglected area. This phenomenon often occurs. It is difficult to diagnose. For example, I have overhauled the failure of a "Fu Yue mercury" ignition system with high pressure and no fire, and checked the car in turn according to the normal inspection steps. In the cold state, the ignition coil and the central high pressure line were checked with a multimeter, and the resistance value was measured, and the result was normal. The primary winding is about 1 Omega, and the secondary winding is about 9K Omega. Turn the engine to check the lead from the collector of the power transistor into the high voltage coil, resulting in no pulse voltage output from the power tube. Continue to measure the base voltage lead from the ECU to the power transistor without base voltage, so the power transistor is judged to be malfunction. Then check the four wire connector of the crankshaft position sensor. The result is normal. There are power supply voltage and pulse voltage in the four lines, so the crankshaft position fault is also ruled out. At the end of the test of ECU, at that time, the maintenance factory did not detect the instrument of ECU, and did not know the testing standard of ECU. At the same time, many maintenance workers expressed different opinions that the computer is an expensive component, the quality and safety should be guaranteed, the damage opportunity is less, it is better not to blindly install and disassemble. I consulted teachers with relevant experience and consulted relevant information to prove that failure of on-board computers is not impossible. So, I took two steps: to dismantle the computer of the malfunctioning vehicle and install it to another Mercury vehicle test to verify the damage of the on-board computer. Verifying the result, the computer has no trouble. Recheck the low-voltage circuit connector and repeatedly measure and check the low voltage circuit. Finally, when checking the computer connector, it is found that the metal sheet in the connector of the signal terminal of the computer and the crankshaft position sensor has fouling corrosion, resulting in bad contact and high pressure without jumping. The fault location, as shown in the imaginary line, is as follows: in summary, the high pressure of the car does not jump, it is caused by the bad contact between the crankshaft position sensor and the contact film of the signal terminal in the computer connector, resulting in bad contact, thus indicating that the cause of the failure is multiple, often deviating from the people. Test the thinking, increase the difficulty of diagnosis. Therefore, it is necessary to attach importance to the training of maintenance technicians and improve the testing methods, techniques, maintenance level and technical level of maintenance personnel.