Idle speed maintenance for engine idling speed between 300 and 800r/min

Category:Automobile engine repair - Date:2016-02-17
The failure of idle travel After starting the engine idle jitter jitter are serious, at any speed is very powerful, the exhaust pipe "chug" sound. Fast speed increase speed, engine burst. The idle speed is between 300 and 800r/min, sometimes it will automatically extinguish, the engine fault lamp is lit, and the exhaust has odour sulfur smell.
Failure analysis of idle speed travel when the.4 cylinder engine has 2 cylinders, the idle speed will appear between 500 and 800r/min idle cars. If the four cylinder engine is missing about two cylinders to 300r/min, the control unit will adjust the idle speed step motor, the idle air valve or the throttle opening. At this time, the idle speed is shown to vary regularly between 300 and 800r/min on the engine tachometer. For example, the idle speed control system (idling step motor is installed on the throttle), at idle speed, you can see the constant switching angle of the throttle, indicating that the idling step motor is constantly adjusting. From low idle speed to constant idle speed. At the same time, there are two cylinders missing, the most common is a ignition coil open circuit. The two cylinders share a single ignition coil and use a series ignition mode. If there is a problem with a ignition coil, it will affect the operation of the two cylinders.
Fault detection for idle travel1. The fastest and effective way is to check the resistance of secondary winding of ignition coil. Using the resistance gear of the multimeter, the range is chosen above 10K Omega, and the high pressure line of each cylinder is pulled out respectively. When the ambient temperature is 20, the resistance values of the high pressure damping line socket between the two synchronous cylinders are checked with two forms of the multimeter, and the ohm table pins are used to connect the high-voltage damping line socket and 3 between the ignition coils 1 and the 4 cylinders respectively. The high voltage damping socket between the 4 cylinders, such as the resistance between the step cylinders is obviously beyond the manufacturer's specified value, the ignition coil assembly should be replaced.
2) using infrared thermometer to detect the working temperature of each exhaust manifold separately, which exhaust manifold temperature is low, which indicates which cylinder is not well burned. If the temperature of two cylinders is too low, the ignition coil should be changed.
3. Infrared thermometer is used to detect the shell temperature of ignition coil. Ignition coil overheating: the surface temperature of the ignition coil is more than 95 degrees C, indicating that the internal short circuit of the ignition coil will cause the high pressure weak, and may cause the sudden extinguishing of the hot car, but it will not cause the lack of the cylinder. The ignition coil is supercooled: when the ignition is started, the surface temperature of the ignition coil is equal to the ambient temperature, indicating the internal circuit of the ignition coil is broken. The ignition coil must be replaced by overheating or overcooling.
Maintenance attention points: The engine with OBD- II system, OBD- II system adopts high precision crankshaft angle measurement method to measure the acceleration of crankshaft rotation at each cylinder ignition, so as to monitor the fire condition of each cylinder. When the fire rate reaches 2 to 3%, the control unit automatically closes the injector and spark plug of the cylinder when the ignition rate is 2 to 3%. When the engine's starting speed is 200r/min, the ignition rate in the cylinder is between 2% and 3%, which will burn out TWC, and the PCM module interrupts the injection pulse signal of the cylinder. When the engine speed is 1000r/min, the fire rate in the cylinder is between 2% and 3%, which will cause excessive emissions. The PCM module interrupts the injection pulse signal of the cylinder. But it will be reopened at large loads. Therefore, the engine equipped with OBD- II system is short of cylinder at idle speed and low load, and it is not short of cylinder when heavy load, which indicates that the cylinder is on fire.
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