Troubleshooting and troubleshooting
    The car before we check, has several in the maintenance station for a comprehensive inspection and maintenance work, but did not rule out the failure. When I proceeded to check, the oil pressure gauge and the computer detector were connected. The customer said that in the event of a failure, suddenly the acceleration was weak, and then the flame was turned off, and then the throttle was no longer used. The car fault is not regular, and there is no fault code output.
    For the fault phenomenon, take the test and in situ repeated start, acceleration and other forms of fault simulation. In the test found that gently depress the accelerator pedal, the probability of failure occurs higher; when the failure occurs, the engine acceleration powerless, and quickly stalled. At this point, the oil pressure is maintained within the standard range (313kPa). Indicating that the oil pump pressure is normal. Consider the car has been done elsewhere in the cleaning tank, fuel injectors and throttle work, therefore, the possibility of troubleshooting the oil circuit. So the focus on the data flow analysis.
    In these data streams, the long-term fuel injection correction values ​​(LongFT # 1) are: + 12.5% ​​(796r / min), + 25% (1388r / min). Short-term fuel injection correction values ​​(ShortFT # 1) are: -12.5% ​​(796r / min), - 21.094 (1388r / min). The most suspicious is the long-term fuel injection correction value, idle at + 12.5%, while the slight increase in the throttle when the + 25%, indicating that the mixture is too long in a lean state, ECU is making thickening correction, and long-term The normal value of the fuel correction should be between -10% and + 10%.
    Mentioned earlier on the oil circuit overhaul, and everything is normal. Therefore, I believe that the cause of long-term fuel injection correction value of the reasons should be abnormal in the air intake signal, so I put the focus of the inspection on the intake air detection. The car used in the hot film air flow meter installed in the rear of the air filter, the assembly is located in the rear right side of the vehicle lights, easy to see. When using the detector to detect, because the engine flame is too sudden, can not collect the air flow meter signal, so first remove the air filter. When removing the air filter, found in the air flow meter in front of the metal filter stained with red foreign body, removed and found a long 90mm, width 30mm plastic paper.
    After seeing this plastic paper, I will know the reason for the failure: when the plastic paper stained in the flow meter position, because part of the flow through the intake channel into the air intake is very small, ECU will consider the smaller intake , While the actual intake is very large, the engine will be because the mixture is too thin and stalled. And when the engine is working (no flameout), most of the time the plastic paper is stained on the part of the flowmeter (when I found the location of the plastic paper), so that the flowmeter will normally detect the flow through its detection Parts of the air. However, due to part of the intake channel is blocked, ECU detected air intake signal is less than the actual intake air volume, which caused the mixture is too thin, ECU to increase the fuel injection time, which is caused by long-term fuel injection value the reason.
   In addition to the above two cases, there is a situation, that is, when the plastic paper away from the air flow meter position, because the flow through the flowmeter at this time unimpeded, you can detect the normal intake signal. But in fact, the total intake air volume has been less than the measured value of the flow meter. In this case, the actual fuel injection will be too large, the mixture will be too thick. This is why the short-acting fuel injection correction value is negative, and the voltage value of the oxygen sensor located at the rear of the ternary catalytic converter is caused by a voltage change of about 0.800 V. This also explains why long-term fuel injection correction values ​​(LongFT # 1) and short-acting fuel injection correction values ​​(ShortFT # 1) are at two opposite values.
    Maintenance summary
    Finally, come back to explore the reasons for entering the plastic paper in front of the air flow meter. According to my analysis, this plastic paper under normal circumstances, it is impossible to enter through the air filter, the only reason is that the last time in the replacement of air filters, attached to the filter on the packaging, not completely clean, Into the rear of the air filter, leading to the occurrence of this failure.