Today I will teach you some diagnostic methods for Nissan cars:
A frozen air conditioning Sylphy.
Failure phenomenon: the car for a period of time, for example, 20 minutes, air conditioning will not come out, but the noise is very large, it is obvious that the evaporator icing, blocking the wind out of the.
The diagnostic process for repair of evaporator icing Sylphy is very early, someone had summarized the principle of the first, simple, complex, the first change of refrigerant, in strict accordance with the 450 grams of filling the new refrigerant, and then not, replace the expansion valve, then replace the compressor. But for this car, the replacement refrigerant has no effect, replace the expansion valve, has no effect, the total does not replace the compressor. Finally, we open the expansion valve, observe the structure, pay attention to the expansion valve at the bottom of the adjustment screw, a screw inner six angle, the original expansion valve can be adjusted. We are based on the principle, tighten the screws, and then test results.
Solution: adjusting the expansion valve screw, you can open the valve to reduce the degree of expansion, reduce refrigerant flow, reduce the pressure of the low pressure pipe, thereby reducing the output of the compressor, so that the evaporator is not easy to freeze.
Two. 1.6 Nissan engine is difficult to start (Livina. Tiida Sylphy.)
Fault phenomenon: whether engine or refrigerator engines are difficult to start the phenomenon
Confirm the fault: start the engine test, about a few minutes after the engine before the engine, the engine is indeed difficult to start.
Initial inspection: the special fault detector test, no fault code display; read data flow, are also normal.
Diagnostic process: pull off the coolant temperature sensor wire side connector after starting the engine, the engine can immediately start the machine. However, after the replacement of the coolant temperature sensor test, the fault is still.
Remove intake pipe after the solar term door is, when starting the engine, to the inlet pipe is sprayed into a little carburetor cleaning agent, mixed gas enrichment, the engine can immediately start a machine. Check the engine intake part, no leakage phenomenon. The data flow of the engine starting is read by the Nissan special fault detector. The basic fuel injection pulse width is 4.1ms, and the actual fuel injection pulse width is 5.6ms. The data flow during the start of normal vehicle engine was read, and it was found that the actual fuel injection pulse width was about 9 Ms. It seems that the fault reason is that the fuel injection quantity is too small at the start of the engine.
Solution: to the engine ECU self-learning can be ruled out. Engine ECU self-learning methods are as follows:
(1) engine warm to normal operating temperature;
(2) the engine speed is maintained at 4 800r/min below, after the start of the vehicle 0KM/h urgent acceleration to 60 km/h;
(3) repeat steps (2), operate more than 2 times;
(4) after the engine is switched off, it can be restarted.
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