Failure phenomenon: a Volkswagen Jetta, driving 140 thousand kilometers, the driver reflected that the car just started the car, engine idling unstable engine jitter, cold car hot cars will appear, not every time, but the fault is more and more frequent, must step on the throttle for a period of time to be good, sometimes in the running of automatic quenching fault diagnosis: After receiving the car, the fault code is read out with 5053. The mixture gas matches more than the limit, the oxygen sensor fails, the engine load exceeds the normal value, the fault code is cleared, and the fault code is read again without the fault code. The instructions are all accidental faults. Then it is normal to start the trial. No driver description of the fault, see the data flow is also in the normal range, a few times, no problem, this car throttle just washed the throttle valve, the forward pipe has changed, doubted the ignition system failure, dismantled the spark plug to see, found that the spark plug is not burnt, replaced four spark plug, heavy The new one matches the throttle once, and the start is normal again. After several successive failures, the engine jitter is serious, and the trouble code is only one engine failure. Then I tried several times. When there was a problem, I saw that the load of the data flow engine reached more than 40%. After a while, I fell down and became normal. The problem was found. The first consideration of the engine engine load detection is that the throttle is the throttle. Open the intake hose and see it. It is unintentionally seen that there is a lot of oil at the new replacement hose interface, and then the throttle motor plug has a lot of oil (just below the throttle), pulling the plug off the plug. A look at it is all oil cleaning plug installed trial run, the problem has never appeared.