Changan Alto car can not start fault detection and maintenance
Fault phenomenon: Changan Alto in the road on the way, the engine suddenly stops, also cannot start again.
Troubleshooting: check that the car at the start, the engine seems to have started. But when the ignition switch is returned to the "ON" position, no matter how the accelerator pedal step to what extent, the engine will soon turn off.
The car is a JL368Q3 type 3 cylinder electronically controlled fuel injection engine. In the engine electronic control device, a total of 6 sensors, namely the inlet pressure of the intake air temperature sensor (both be made one), solar term door position sensor, camshaft position sensor, coolant temperature sensor, oxygen sensor and knock sensor. By using the special fault diagnosis instrument provided by the original factory, the output of the non fault code is detected. And then the engine for routine inspection.
First, the ignition system is checked. When the positive light is used to check the ignition timing, the ignition timing is + 1 + 7, in the normal range. Re testing of fuel pressure. Unplug the fuel pressure regulator on the vacuum tube, oil pressure up to 300kPa, with a vacuum tube when the oil pressure up to 280kPa, are in line with the standard. Check the oil supply system is sealed, when the oil pressure reaches 280kPa, close the ignition switch 10min, oil pressure can be maintained at more than 150KPa, but also in the normal range.
Finally check the cylinder pressure, measured in the 1100-1150kPa, there is no problem.
From the failure phenomenon the car, a car to turn to restart the engine idling process, will generally not overnight because of the oil and the spark plug flooded, causing fire point. So it should be focused on the search for the reasons of mixed gas. The main signal is the signal of the intake pressure sensor, the correction signal is the signal of the coolant temperature sensor and the air inlet temperature sensor. The main signal is the signal of the air inlet pressure sensor from the engine ECU. Since the correction signal does not play a decisive role in the engine idle speed, the problem is mainly concentrated in the signal provided by the intake pressure sensor. In order to simply act, the intake pressure sensor is pulled out, the use of ECU's self rescue function, that is, ECU uses the throttle position sensor provided by the signal control of the fuel supply. Starting engine, really effective, the engine was started immediately, but the high idle. It seems that there is a problem of air intake pressure sensor.
After the new intake air temperature sensor is changed, the engine is completely normal.
Failure analysis: the car fault in the analysis of the existence of a certain degree of difficulty. Because of a fault diagnosis instrument is used, does not show the fault; two is the engine, can not carry out dynamic detection; three is the fault signal processing of engine intake air pressure sensor, many models adopted open circuit or short circuit only shows fault code, and the signal voltage is too low or too high is not displayed, to bring the difficulty of fault diagnosis.
So in the case of this failure, can not simply rely on the change of various elements to luck, but should fully understand the basis of electronic control engine, relying on three elements, the engine work step by step, step by step to judge fault analysis.
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