Troubleshooting with data flow. (Dieselpartsworld)        2016-01-17   

Data flow fault diagnosis method is a basic method to eliminate the faults of electronic controlled engine.
The normal work of electronic control system of some of the main sensor and actuator parameter values (such as speed, battery voltage, air flow rate, time of fuel injection, throttle opening, ignition advance angle and coolant temperature) to provide maintenance andcombined according to different requirements, form a set of data, known as data stream.
The standard data flow is provided by a factory, or data is extracted in the normal running of the vehicle, engine monitoring work in various states. In the course of the electric vehicle, the fault self diagnosis system also has the function of recording, which can record the relevant data in the process of automobile driving.
Use, these data can be through fault detection instrument, the various sensors and execution element input and output signals of the instantaneous value is displayed in the way data on the screen, so you can according to the data of all sorts of data in the working process of the car changes (fault) and the normal running of the data or standard data flow comparison, can diagnose the faults of electronic control system.
For example, a car Jinbei VAN Engine at startup, warm machine stage work, normal driving for a period of time, elevated temperature after engine continuously take the phenomenon of black smoke, accelerates the exhaust pipe will chug, power down, serious when can't hang a gear drive.
Because of lack of the vehicle power, a chugging exhaust pipe, the reason may be:
Individual cylinders are not working well, take black smoke, which shows that there is a problem of mixed gas concentration. After the circuit (spark plug, ignition coil, high voltage line) and the oil circuit were examined, are not found abnormal, the reason may be in the air intake system. With the detection instrument diagnosis, no fault code display, the data flow diagnosis method for its idle condition (no fault) the main data were extracted, the main data are as follows:
Engine speed 760 ~ 800r / min
Injection pulse 0.6ms
Ignition advance angle of 7 degrees to 14 degrees
Inlet pressure 30.8kPa
Coolant temperature 80
The throttle opening is less than 5.5
When the road test, driving a few tens of kilometers, the engine on the above fault phenomenon. Stepped on the accelerator pedal, the exhaust pipe has the chug of dull, and then observe the idling condition of data flow and the main data are as follows:
Engine speed 560 ~ 920r / min
Injection pulse 4.5ms
Ignition advance angle of 7 degrees to 21 degrees
Inlet pressure 100.2kPa
Coolant temperature 92
The throttle opening is less than 5.5
The contrast with the cooler when the data flow engine data flow, the most obvious changes is the intake pressure and fuel injector pulse two data. From the above data, the cause of the failure of the machine may be in the intake system, may be due to the intake pressure sensor signal caused by abnormally high.
Pull off the vacuum hose on the intake air pressure sensor, and feel only a weak vacuum suction, the vacuum is the root cause of the failure of the above. So the throttle valve was checked. Remove the throttle, check the site of vacuum sensor source, throttle body and manifold seat with asbestos gasket seal, in body temperature and oil steam erosion, asbestos pad is not pressed portion of the bubble expansion layer, blocking the narrow vacuum source channel, the cooler asbestos pad bubble expansion has reduction, fault disappears. After this part of the excess gasket cut off, after loading the test, the fault will be eliminated.