Why do cars stall when they collide?
If the engine sometimes shuts down at idle speed, and it is normal after restarting, we call it "intermittent idle flameout". This kind of fault is difficult to check for many reasons, and all kinds of parts or lines are not completely damaged. What's more troublesome is that the engine can return to normal even if it is turned off occasionally and then restarted. Therefore, even if the engine is turned off at idle due to the sensor, the engine electronic control unit will think that this phenomenon is not a fault and will not be recorded by the engine electronic control unit, so it is impossible to obtain information about the fault from the fault diagnosis system of the engine electronic control unit. The reasons for "intermittent idle flameout" are generally: the engine idle motor is stuck; The wire sheath of idle motor is somewhat worn; Idle air hole is too dirty; There is something wrong with the engine throttle position sensor; There is a problem with the camshaft position sensor or crankshaft position sensor; Engine speed sensor is faulty or too dirty; There is something wrong with the idling control program of the engine electronic control unit, and so on. In addition, if there is a problem with the quality of gasoline, it will also cause this failure.
I once repaired a 3.8 liter Chevrolet bullet. When the vehicle arrived at the repair shop, the driver reported that the engine was not idling, and it was confirmed as "not idling" after the test run. After inspection from easy to difficult, it was found that the engine idle motor was stuck by carbon deposit and could not be repaired, so the idle motor could only be replaced. During the maintenance process, I learned from the conversation with the driver that the car started idling a month ago, but it was normal to restart after each flameout, so I didn't come for maintenance, and there was no idling at all this time. After cleaning the throttle body and replacing the idle motor, everything returned to normal. I guess it was all caused by the idle motor. I told the driver that it would not idle for a while. However, after two days, the driver drove over and said: Sometimes there will be idling flameout. Just like the original question, he asked us if there is something wrong with the quality of the idling motor. After preliminary inspection, there is no problem, there is no problem with the idle motor, and the engine fault light is not on. Only TECH 1 (special detector for general motors) can be used to detect the dynamic data of the engine. About half an hour later, it was found that the speed sensor value suddenly dropped, the engine stopped, the engine was restarted, and the idle speed returned to normal. Immediately check the engine speed sensor and find that the sensor is dirty and has a thick layer of oil on its surface. Remove and clean the sensor and install it before starting the engine. After trying for an hour and a half, the flameout didn't happen again. It is estimated that the problem has been solved. When we visited the customer a week later, the driver told us that there had been no idling flameout since then. It is concluded that the intermittent idling flameout of the car is caused by the unclean engine speed sensor, and the "no idling" caused by the stuck idle motor is just a coincidence, but it still gives us an illusion and makes us go the wrong way.
Idle flameout generally does not cause any harm, because when the engine is idling, the vehicle often stops. If idling flameout occurs when the vehicle is taxiing, corresponding measures can be taken to avoid danger because it is far away from the obstacles in front. Of course, if you happen to turn off the engine when braking suddenly, it will be very harmful, because once you turn off the engine, the brake vacuum booster will not work, which will greatly reduce the braking efficiency of the vehicle, and the direction assist device will also fail, making the vehicle turn sharply. If you add your panic, the accident will be hard to avoid.
If the vehicle is "not idling", it should go to the repair shop as soon as possible to ensure driving safety. If the vehicle "idles intermittently", we can take the following corresponding measures to avoid danger when turning off the engine:
1. If the engine stops while waiting for parking, just restart the engine. If it is an automatic car, before restarting the engine, be sure to put the gear into park (P gear) or neutral (N gear).
2. When the vehicle turns off during taxiing, don't panic, keep the direction stable, and take a little braking as appropriate. If it is a manual car, you can step on the clutch, put the gear lever into the corresponding gear according to the vehicle speed, then release the clutch and start the engine by using the vehicle speed, which is similar to starting the engine with a big car, or you can restart the engine directly; If it is an automatic car, first carefully shift the gear to neutral, and be careful not to shift to reverse gear (R gear) by mistake, otherwise the transmission will be damaged, and then restart the engine. Of course, you can also turn on the double jump light to park the vehicle and restart the engine.
Don't be nervous and keep the direction stable in case of flameout when braking. Measures can be taken to increase the braking force, while paying attention to the surrounding situation. If you have the chance, you can change lanes and bypass the obstacles in front. Pay attention when turning the steering wheel, because without direction assistance, the steering will be heavier.
Give oil when starting to lift the clutch, because the waiting speed of most cars is relatively low. If you don't step on the accelerator when the clutch is almost full or when the clutch is lifted too fast, it is easy to stall (especially when the clutch is suddenly lifted uphill). A slow start is not a problem. You can see that other people's fast start is the result of 1 gear hitting the accelerator. Hold hands when parking on a slope. At the beginning, just follow the guidance of the school coach. Slow refueling and slow refueling at any time are good for the engine. Especially in low gear)
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Finishing by jrliu78 and Xin Qing can't.