A modern Beijing tousson car with a mileage of about 146 thousand km and a 2. 7L engine. Users reflect: the vehicle in the last period of time in the occasional speed of acceleration is not smooth, and sometimes the phenomenon of sudden flameout, and there is a certain rule, every time a red light or normal driving pedal after the acceleration of the pedal more times. If the engine is started immediately after the fire is extinguished, it will be difficult for the engine to start the car. It must start several times or lightly pedal the accelerator pedal before it can start smoothly. The user has replaced the idle control valve, cleaning the throttle valve, the symptoms at that time after each maintenance seems to disappear, but not long before the same problem will appear, but the failure can not be thoroughly solved. Troubleshooting: the engine system was detected first with a diagnostic instrument, and the reading fault code was P01709 [fuel correction (mixed ratio)], P0150 [the oxygen sensor signal card was stagnation in the state of mixed gas concentration (1 row / sensor 1)] and P0123 (high voltage of the throttle / pedal position sensor circuit). There are 3 fault codes, which indicate that the mixture is too strong and the throttle position sensor signal is too high. Because the car has been repaired several times, it is not completely solved, so it is not possible to change the parts. So we want to observe the real-time data flow of the vehicle through the road test to see if we can find out the fault correctly. After removing the fault code of the vehicle with the diagnostic instrument, the diagnostic instrument is connected to the diagnostic instrument and into the data flow detection of the engine, and several key data streams are locked in real time, which are the idle speed control valve duty ratio, the throttle position opening, the throttle position sensor voltage, the engine target speed, the actual speed and the purification control. Valve duty ratio, oxygen sensor voltage, air flow sensor intake, purge control valve duty ratio and so on. In the course of driving, the vehicle did not extinguish, and the vehicle did not flameout. The observed data flow was not found abnormal. The vehicle did not flameout. The observed data flow did not find abnormal. The duty ratio of the idle control valve, the opening of the throttle, the voltage as the throttle of the vehicle increased, the control valve was purified. The duty ratio is not abnormal. The voltage of the oxygen sensor varies rapidly from 0.1 to 0. 9V. Once again, the fault code is read by the diagnostic instrument, the system is normal, and there is no fault code. Is it accidental trouble that clears up the problem and solves the problem? But the vehicle that the user reflects is flameout is a little more opportunity to appear after the red light or the acceleration pedal is loosened at the end of the speed, so it is only the key to simulate the two working conditions, see if the fault can be tried out, and then through the above analysis of the key data, see if we can find out the barrier. By repeatedly deliberately parking, speeding up and loosening the accelerator pedal, it didn't take long for several key data streams to lock in. After a rapid acceleration, the driver's foot has completely left the accelerator pedal and the vehicle is in the taxi stage. However, the opening of the throttle position in the data flow has been shown to be 34 degrees, the voltage of the throttle position sensor is 1. 7V, and the voltage of the oxygen sensor pulsate slowly from 0.6 to 0.8V. At last the vehicle almost stopped. The throttle has already been closed, the air is through the bypass air inlet control valve into the intake port, the vehicle should actually work at idle speed, but the data flow shows that the throttle opening is 23.9 degrees, the signal voltage of ECM is 1. 3V, and the full open 1/3 is reached, even if the control block is the buffer control after the throttle is pine oil. But the vehicle has been stationary at idle speed, and at that time the ECM control signal to the actuator will not be executed according to idle speed. At this time the injector pulse width is 15ms, the injection pulse width is very abnormal, the fuel injection pulse width is 2.5 ~ 6ms under the idle speed, the intake is not enough, the fuel is too much, the mixture is too thick, so the vehicle will certainly go out. As a matter of time, the vehicle naturally extinguished. Failing to step on the accelerator pedal, it failed several times, stepped on the accelerator pedal and started the engine smoothly, as reflected by the users. It is obviously caused by the throttle position sensor, which gives ECM an almost medium load error signal at the idle speed of the vehicle, which makes the combustion chamber of the engine combustor thick, the spark plug short and the final vehicle out of fire. If you step on the accelerator pedal at startup, after the throttle is opened, the mixture is diluted, so it is easy to start. After replacing the throttle position sensor, the road test is carried out, the engine works normally, the extinction phenomenon is disappeared, the road test is accelerated, and the fault is completely solved. Troubleshooting: Although the case has the fault record of the relative throttle position sensor, it is sure that the single fault code analysis is a problem of the throttle position sensor, and it is a bit too arbitrary, and it can be quickly and accurately judged by the combination of data flow. Although the fault is obvious, it can be found only through idle data. But there are still problems in the vehicle itself, but as the data of the driving are constantly changing, and no standard data flow can be compared, it is very difficult to analyze the true and false. In the idle condition, the standard data flow can be compared to the reference, and there is so obvious fault phenomenon at the idle speed, so the use of the idle state of the data flow can quickly and accurately solve the problem.