Engine common faults
EFI engine idling jitter troubleshooting
The decrease in engine speed is not obvious, which indicates that the cylinder is bad, and the spark plug and injector of the cylinder should be disassembled and inspected. 3) Check the throttle position sensor. If the idle switch in the throttle position sensor cannot be closed when the throttle is fully closed, the throttle position sensor should be readjusted or replaced. 4) Use the data analysis function of the car computer tester to detect the water temperature sensor. If the water temperature value transmitted from the water temperature sensor to the engine computer does not match the actual water temperature, the water temperature sensor is faulty and should be replaced. 5) Use a computer tester or multimeter and oscilloscope to check the air flow meter. If it is abnormal, replace it. 6) Unplug the idling control valve harness during idling. If the phenomenon of fluctuations in idle speed disappears, but the phenomenon of instability of idle speed worsens, it means that the idle control valve is normal and the fuel injection system is faulty. If the idling fluctuations do not change, the idling control valve is defective or not.
For this, check whether there is a pulse electric signal at the idle control valve harness connector. If there is no signal, it means that the control circuit or computer is faulty. If there is a signal, it means that the idle speed control valve is stuck. The idle speed control valve should be disassembled or replaced. 1) When the engine is idling, the body shakes and the tachometer pointer rapidly vibrates up and down; 2) When the engine is idling, the speed is suddenly high or low. Capacitive three-point oscillator (also known as Cowz oscillator): A kind of excavator maintenance for self-excited oscillators introduces the hydraulic system of imported excavators comprehensively, systematically, and specifically. The structure and working principle of the pump, valve, motor, hydraulic cylinder and auxiliary components in the hydraulic system are introduced in detail, and the disassembly, repair and installation methods of each piece are described in detail. In each model, the electronic control system and fault diagnosis and elimination methods are also introduced systematically. It consists of a series capacitor and inductor loop and a positive feedback amplifier. It is named because the three ends of the two series capacitors of the oscillation circuit are connected to the three pins of the oscillation tube.
Loop filter: a low-pass filter with the following two functions: attenuating high-frequency error components at the output of the phase detector to improve the anti-interference performance; when the loop jumps out of the locked state, it improves the loop for short-term storage , And quickly restored the maintenance of the signal excavator. The hydraulic system of the imported excavator was introduced comprehensively, systematically, and specifically. The structure and working principle of the pumps, valves, motors, hydraulic cylinders, and auxiliary components in the hydraulic system were introduced in detail. The method of disassembling, repairing and installing each piece is described. In each model, the electronic control system and fault diagnosis and elimination method are also introduced systematically. Differential circuit: A circuit in which the output voltage and the input voltage have a differential relationship. And capacitor. VCO oscillator (oscillation): in the oscillator circuit using voltage-controlled components as frequency control device oscillator, vco is an abbreviation for voltage-controlled oscillator. Minimum frequency shift keying (gmsk): is a kind of modulation The back spectrum has a narrow main lobe and fast side lobe fading.
In order to meet the requirement of the channel width of 200khz required by the gsm system, the modulation technology can save the frequency resources. pcm coding (also known as pulse code modulation): one of the coding methods for digital (Resources) communication. The main process is to sample the analog signals such as voice and image at a certain time (time) to make them discretized. At the same time, the sampled value is rounded and quantized according to the stratified unit, and the sampled value is based on a set of binary codes. To represent the amplitude of the sampling pulse. Time division multiple tdma and carrier frequency multiplexing technology: The gsm system uses frequency division multiplexing technology. The entire frequency band is divided into 124 pairs of carrier frequencies, with a carrier frequency interval of 200khz and a duplex interval of 45mhz. The uplink frequency band (to the mobile station) is 890mhz-gl5mhz, and the downlink frequency band (to the mobile station) is 935mhz-960mhz. In the uplink and downlink frequency bands, the frequency of the carrier frequency pair n (n = l ~ 124) is fu (n) = 890 + 0.
2nmhz (uplink) or fd (n) = 935 + 0. 2nmhz = fu (n) + 45mhz (downlink). In each radio frequency channel, the GSM system uses time division multiple access technology. Each carrier frequency is divided into tdma frames according to time with a frame length of 4.6ms. Each tdma frame is divided into eight time slots and the time slot is long. For 557ps. Therefore, there can be 8 mobile phones on one carrier frequency at the same time (one mobile phone occupies one time slot). GSM mobile phones use the same time slot number when receiving and transmitting, and the start time of the received tdma frame is delayed by 3 time slots relative to the start time of the transmitted tdma frame. That is, the interleaving of tdma frames avoids interference caused by gsm receiving and transmitting at the same time at the same time, so gsm mobile phones do not use expensive duplex filters, which also reduces costs. Digital (Resources) signal modulation and demodulation technology: In order to meet the strict requirements of mobile communication on adjacent channel interference.
Gaussian filtering minimum frequency shift key modulation (gmsk) is adopted. This gmsk modulation method has a modulation rate of 270833 kbe. Each time division multiple access tdma frame occupies a time slot to send pulse clusters, and its pulse cluster rate is 33.86 kbo. Anti-interference and anti-fading technology: The GSM system uses cyclic redundancy code speech data for protection to improve (the ability to detect and correct errors (that is, channel coding technology). It uses 456bit data in one voice frame to be distributed to adjacent Of 8 time-division multiple-access tdma frames, even if a time-division multiple-access tdma frame is lost, it can be recovered by channel coding; adaptive equalization technology is used to solve symbol crosstalk caused by delay extension caused by multipath fading; pseudo-random Frequency hopping sequence (frequency hopping 217 times per second, that is, one frequency per frame), solves the problem of co-frequency interference and frequency selective fading. Speech coding and decoding technology: gsm system uses a regular pulse excitation linear prediction with a long duration Coded rpeltp program.
Divide the voice into 20ms frames for encoding and generate 260bit voice frames (with a coding rate of 13kbo) to ensure voice quality and improve spectrum utilization. Modulation: Modulation is to add audio signals to high-frequency oscillation waves, and use audio signals to control (high-frequency) parameters. Demodulation: The process of taking the audio modulated signal from the modulated wave is called demodulation. Oscillator: A circuit combination that can convert direct current into a signal with a certain frequency. Oscillation circuit: refers to a circuit maintenance composed of reactance elements with integrated general parameters or distributed parameters. The excavator performs periodic vehicle cleaning, component inspection lubrication, and replacement and maintenance of damaged parts. The main purpose is to be effective To ensure the working effect and good technical condition of the excavator.
Avoid the occurrence of failures due to the wear and tear of parts, and provide a good guarantee for people's safety. Phase-locked loop (PLL): It is a control system that realizes automatic phase lock. It generally consists of phase detector, loop filter, voltage controlled oscillator and other components. D / A conversion circuit: also known as digital film analog converter, referred to as digital film converter for short. A circuit that converts a digital quantity to its corresponding analog quantity. A / D conversion circuit: also known as analog (definition: virtual to real thing or process) digital converter, abbreviated 卞 convergent converter. A circuit that quantizes (discrete) an analog quantity or a continuously changing quantity and converts it into a corresponding number-quantum quantity. Microprocessor: A part of a computer system that can independently execute a stroke sequence to complete the processing and processing of data and instructions. It consists of a data processing component, an instruction processing component, and a memory controller. By executive function (gōngnéng).
Can be divided into central processor, peripheral processor and interface communication processor. Memory: Also called memory device. It is a device that stores data and various programs in the microprocessor. It is an important part of a microprocessor. It consists of a storage unit assembly, an address register, and a decoding drive circuit. The sense amplifier and timing control circuit are composed of several parts. Filtering: A frequency selection technique that passes only the required spectrum in a signal and filters out other spectrum. Its basic form is to make use of the frequency reactance characteristics of inductors and capacitors to appropriately combine inductors and capacitors in the circuit to form a filter network to complete the frequency selection. The actual inductor-capacitor network can also transmit and suppress the frequency band. In addition, there are resonant filters using piezoelectric crystals, piezoelectric ceramics, and mechanical vibrators, as well as various active filters. They have strong frequency selection performance, and their applications are becoming more and more widespread. Surface acoustic filter: a layer of metal film is evaporated on a material substrate with piezoelectric effect.
Then through photolithography, a pair of interdigital electrodes are formed at each end. When the signal voltage is applied to the transmitting transducer, an electric field is formed between the input fingers and the piezoelectric material is mechanically vibrated (ie, ultrasonic waves). The energy is transmitted to the left and right sides in the form of ultrasonic waves, and the energy to the edge Absorbed by sound-absorbing material. At the receiving end, the mechanical vibration is converted into an electrical signal by the receiving transducer and output by the interdigitated electrode. Varactor diode: also known as variable reactance diode. It is a diode made by using the pn junction capacitor (or contact barrier capacitor and its reverse bias voltage vr) and its principle. The material used is mostly silicon or single crystal, and epitaxial process technology is used. Reverse bias voltage The larger, the smaller the junction capacitance. Varactor diodes have series resistance related to the resistivity of the substrate material. The main parameters are: zero bias junction capacitance. Zero bias excellent value, reverse breakdown voltage, center reverse bias , Nominal capacitance, capacitance variation range (in picofarads), and cut-off frequency.
For different applications, variable capacitance m-poles with different c and vr characteristics should be selected. For example, an electrically controlled varactor diode dedicated for resonance circuit tuning, a reference varactor diode suitable for reference amplifier, and a multiplier for solid power source. Frequency, phase shifted power step varactors, etc. In-phase: refers to a phase relationship where the phase difference between two alternating currents of the same frequency is equal to zero or 180 degrees. Inversion: refers to a phase relationship where the phase difference between two alternating currents of the same frequency is equal to 180 degrees or an odd multiple of 180 degrees. Orthogonal: refers to the phase relationship between two alternating currents of the same frequency with a phase difference of 7ta. Tuning: refers to the process of changing the reactance parameters of the oscillating circuit to make it resonate with the external signal frequency. Detune: Also called. Refers to the deviation of the natural frequency of a resonant system from the external frequency acting on the system. Frequency offset: Abbreviation for near-frequency offset. Refers to the maximum deviation of the instantaneous frequency of the FM wave from the carrier frequency.
Fundamental Wave: Also called the first harmonic. It refers to the wavelength or frequency component of the non-harmonic periodic oscillation that corresponds to this period. Harmonics: refers to a sine wave with a frequency n times the frequency of the fundamental wave. Together with the fundamental wave, they are spectral components of non-simple harmonic cycle oscillation. Channel: refers to the medium or channel through which information is transmitted in the communication system. Encoding: The process of processing the original (Original) signal according to certain rules at the sending end in order to achieve a predetermined purpose. Decoding: Refers to the process in which the receiving end uses the opposite procedure to encoding to convert a pulse code modulated signal to a pulse amplitude modulated signal. The main equipment consists of some logic circuits and constant current sources. Frequency division: A method of changing a higher frequency signal into a lower frequency signal. Frequency doubling: A method of changing a lower frequency signal into a higher frequency signal. Nonlinear circuits (Circuits) are usually used to generate a series of harmonics from the fundamental wave. Then the required multiples of harmonics are selected through a band-pass filter to achieve frequency doubling. Mixing: The process of changing electrical oscillations at two different frequencies into electrical oscillations at a new frequency through a non-linear piece.