Here I want to introduce the content of the engine is analyzed by oxygen feedback test.
First, the system operation analysis (O2FB—- oxygen feedback balance method):
In the past 30 years, the ignition oscilloscope in a car repair industry is so useful is the ignition oscilloscope to “see” the electronic signal, not only can see the ignition system, can also help to detect faults of many electronic and mechanical aspects. For the sake of simplicity, the process of using an automotive oscilloscope to measure or verify the oxygen sensor signal is referred to as the oxygen sensor feedback balance process.
The oxygen sensor is the process of diagnosis and repair of the balance verification process, the car received oxygen sensor oscilloscope circuit through the process technical maintenance personnel, to verify the oxygen sensor itself is working properly, and then analyze the waveform, and then determine what needs to be repaired (electronic or mechanical), delivery of the vehicle fuel in the repair after verification feedback control system fault whether it has been excluded or also need to re test
In the process of available oxygen sensor feedback balance analysis method to diagnose the vacuum leak, ignition, bad sprayed with unbalance and cylinder pressure, the use of the hands of the oxygen balance feedback skills will have the ability to re adjust the car in practice.
A new method for fault diagnosis of electronically controlled engine based on oxygen feedback balance.
Two, oxygen feedback balance test steps
Three, electronic ignition (EI) secondary single cylinder waveform
Ignition secondary single cylinder display waveform main purpose:
1, analysis of the single cylinder ignition angle (ignition coil charging time analysis);
2. Analyze the performance of ignition coil and secondary high voltage circuit;
3, check the single cylinder mixture air ratio is normal (combustion line analysis);
4, find out the cause of the cylinder off the fire (combustion line analysis, determine the dirty or broken spark plug).
This test can provide valuable information about the cylinder ignition and combustion quality. If necessary, the test can be carried out under the conditions of the exercise. Because the ignition secondary waveform is obviously affected by the engine, fuel system and ignition conditions, it is very useful to detect faults in the engine and fuel system components and ignition system components. At the same time, different parts of each ignition waveform can also be used to identify the faults of some components and systems of the corresponding cylinder ignition system. This point can be determined by referring to the waveform of the knowledge points to see the corresponding changes in the waveform of specific segments. The display parameters of each part of the waveform are displayed in the digital display on the display.
Waveform analysis:
Baotou North heavy truck parts ignition coil charge: observe the ignition coil at the beginning of charging, should maintain a relatively consistent waveform along the edge, which shows that the same angle of the cylinder and ignition timing accuracy
Baotou North heavy truck parts ignition line: observe the fire jump height of each cylinder of the consistency, in the case of rapid acceleration or high load, due to the increase in combustion pressure, the peak value of the jump fire will increase. Any actual deviation from the peak height of other signals may mean a fault.
Spark or burning or combustion spark voltage: observation voltage remained relatively consistent, suggesting that the consistency of the Baotou beiben heavy truck parts the spark plug and the cylinder air-fuel ratio, if the mixture is too thin, the burning voltage is lower than normal number.
Burning line: To observe a spark or burning line should be very “clean”, not too much clutter in the burning line, too much clutter indicates that the cylinder misfire, due to premature damage ignition injector, dirty spark plug or other reasons. The duration of the combustion line indicates that the mixing ratio is very thin or abnormal. The excessively long combustion line (usually over 2 milliseconds) indicates that the mixture is thick, and the short combustion line (usually less than 0.75 milliseconds) indicates that the mixture is thin.
Ignition coil oscillation: observe at least two, preferably more than three oscillating waves behind the line, indicating that the ignition coil and capacitor (in platinum or ignition system) are good.
The dynamic peak detection display mode is very useful for the detection of intermittent faults in each cylinder ignition process.