Case 1
Failure phenomenon: a 2008 model-year new Nissan Teana sedan 2.0 L, equipped with MR20 engine and Xtronic CVT transmission. Say users, the car running in the urban area for a long time, if the red light when the shift lever is in the D range, the rear portion of the vehicle body occurs ldquo; goo goo rdquo; abnormal noise (FIG. 1).
FIG 1
Check Analysis: In some specialty stores this failure encountered. After a long time vehicle driving in urban areas, since the stop and go low speed, the engine combustion water accumulated in the muffler main cause the mounting position of the main muffler lowered by gravity, so that the cushion rubber mount pad losing the role of the working engine vibration muffler driven by a bracket pad directly to the vehicle body, resulting in abnormal noise.
Although found the cause of the malfunction, but a lot of maintenance does not completely solve the problem. After I checked a multi-vehicle car found fault, muffler support pad below the obvious signs of interference (Figure 2). According to the causes of abnormal noise generated, I believe that as long as the problem of solving the interference pad holder, abnormal sound can be excluded,
FIG. 2
[ 123]
Figure 3
Troubleshooting: using a razor blade under the stand pad protruding portions cut away (FIG. 3), and the bracket pad and refitted main silencer, confirm the failure by tracking returning period exclude.
Review Summary: Many new models are usually listed at the beginning there will be some failures, manufacturers of components and the corresponding technical support to improve to have a process, so in order to reduce customer complaints in practical work, maintenance staff ensure that the vehicle you can make some changes to the corresponding parts under the premise of safe use.
Case 2
Failure phenomenon: a 2007 annual Nissan Tiida 1.6 L sedan, equipped with RE4F03B HR16DE engine and automatic transmission, mileage 30000 km. According to users to reflect, in normal driving the car engine stall phenomenon.
Analysis of examination: Road test and found that failure are quite obvious, traveling about 2 km away in the engine stalled three times, each time the flame is at a red light appears vehicles, as engine power and gradually disappear flameout. The gear shift lever into the parking D, sometimes the engine will be significant jitter, the shift lever is placed in the P range and N range during normal engine operation. Nissan dedicated connection CONSULT-Ⅲ diagnostic fault diagnosis system trouble code storage. Data flow into the engine is detected (FIG. 4), oxygen sensor voltage is found lower (only 0.07 V), and no change in air-fuel ratio varies between 108% to 117%. Unstable engine idling, the air-fuel ratio when the engine idle jitter value increases significantly.
Figure 4
After the communication with the user know, at the last car has been the maintenance and cleaning electronic throttle intake system for demolition cleaning. By analysis of the data stream, the oxygen sensor and the air-fuel ratio data demonstrate too lean mixture. Because no intake system leak checked the situation, the possibility of too little fuel injection so should be considered. Then check the injector, the maintenance personnel is not found after removing obvious injector clogging, but each of the injectors 3-4 are black orifices.
Troubleshooting: cleaning the injector and observe the situation injector atomizer conditions found four injectors have poor atomization. After loading injector cleaning, test troubleshooting, data flow engine back to normal (FIG. 5).
Figure 5
reviewed: In fact, many of the automotive electronic control system failure can be judged by the engine fault location data stream, for example through the air fuel ratio and the oxygen sensor voltage data analysis fuel injection amount is too small, then needed to validate a solid theoretical basis of our judgment.
(Yang Weijun)