Respectively read engine control system data stream and make comparison in the static (ignition switch in the ON gear, do not start the engine), idle (engine operating under no load condition), high-speed (engine operating at speed of 2000 rpm) and found that cylinder 5 compensation remain unchanged. Therefore, engine can be judged to have slight jitter and loud noise, poor acceleration, exhaust pipe has a small amount of black smoke, which have a great relationship with 5-cylinder, working conditions of each cylinder can be judged through off-cylinder in [function test]menu on scanner menu. To perform off-cylinder test respectively on 1-cylinder, 2-cylinder, 3-cylinder, 4 cylinder, 5-cylinder, 6 cylinder, found that engine running no change only when cylinder 5 off and engine obviously jitter when other cylinders off. Thus can identify 5-cylinder working abnormal, the reason for which excludes mechanical parts problem, and electronic control system has no fault codes. Such failures are generally beyond monitoring range of ECU . Under the state of engine is started, using a stethoscope to monitor working conditions of each injector one by one, the result is the voice of 5-cylinder injector work relatively insensitive, unlike the other cylinder work sounds so crisp, thus can determine the 5-cylinder fuel injector work abnormality. Remove five-cylinder fuel injector and test on test bench, and found that 5-cylinder fuel injector leak, which can determine the fault is caused by injector leak.

Trouble Removal
Test run after replacing cylinder 5 injector and write in injector QR code,fault phenomenon disappear and fault completely removed.

Maintenance experience
It might be comprehensive fault when diesel electronic control system has no fault code, and needs comprehensive overhaul and analysis after summarize according to the data of vehicle. For vehicle that adopts Denso electronic control system, after replacing computer panel and injector, injector code should be written into the computer board. Otherwise, the engine fuel consumption will increase, affecting the normal operation of vehicles and fuel economy.
Note: The following circumstances need to encode the injector

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