Breakdown phenomenon: The BMW 750i car of engine of an equipment V12, M70, vent-pipe risks black smoke, idle fast flabby, the vent-pipe when quickening 1000-1500r/min " blowout " ; In travel process, enter electronic-controlled and automatic transmission by fits " invalidation is protected " condition -- appear on indication screen of appearance information liquid crystal " TRANS PROGRAM " model of written characters, hang into D, 3, the speed when archives adds L not to rise, although quicken footplate to walk to also can be maintained only completely,be in 800 ～ 1000r/min; Meeting flameout is returned sometimes in travel, but can start again immediately; Hang into archives of N, P, engine is quickened good; Engine trouble emergency warning lamp illumes sometimes.
Breakdown diagnoses with eliminate: Because engine trouble emergency warning lamp illumes sometimes, so the decision reads the breakdown code that takes engine report to control a system above all, the sky that indication breakdown code shows engine is lighted than undesirable.
In system of door of cognizance solar term normal circumstance falls, check the signal voltage of oxygen sensor: archives of avometer park volts d.c. , expressing a pen to be received respectively left, on the right side of oxygen sensor signal outputs a line (black line) , the pen that bear a watch receives automobile body (the) that take iron, read sensor extraction oxygen to be in idle fast the output signal voltage when. The result shows left oxygen sensor is in idle fast the output signal voltage when changes inside the normal limits in 0.1V ～ 0.9V, and on the right side of the signal voltage that oxygen sensor outputs is 0.2 ～ 0.3V only, the mixture gas of air cylinder is too rare on the right side of this specification. To confirm further, will left, on the right side of installation of oxygen sensor trade, detect again their output signal voltage, the result still is indicated on the right side of oxygen part is contained in engine eduction waste gas too big, mix air air to light namely bigger than passing. Again trade installs flow transducer of left, right air, the case is such still.
Be aimed at this one circumstance, first engine lights oil pressure force on the right side of the examination (the motor that BMW 750i car uses mutual independence controls a system, control respectively left, right two side engine, the fuel that has two independence consequently supplies a system, fuel passes pump of two dynamoelectric gasoline to output, answer oily) jointly again. Test eventuate: In idle fast operating mode falls, fuel pressure is 274.6KPa on the right side of, accord with technical requirement. Then, right on the right side of 6 fuel injector have engine clean. After clean job is finished, measure again on the right side of the output signal voltage of oxygen sensor, still be 0.2 ～ 0.3V.
Examine ignition system then, in order to assist analytic breakdown. Be opposite with ignition voltage instrument left, on the right side of advocate high-pressured report reachs a report of crock high pressure to undertake checking contrast. Result discovery, left engine is in advocate below the circumstance that high-pressured report amounts to 10 ～ 15kV, report of crock high pressure is 7 ～ 9kV, and on the right side of engine is in likewise advocate below the condition that high-pressured report obtains 10 ～ 15kV, report of crock high pressure is in more 1 ～ 3kV, only the 3rd, electric energy of 4 crocks of high pressure achieves 7kV. Will left, on the right side of engine ignition system is departmental (flame of the sparkplug, line that divide a crock, ignition distributor lid, cent and high-pressured coil) compare after trade, engine ignites on the right side of still abnormal. During this, still had checked left, on the right side of the compression of one-cylinder pressure, the outcome is different, on the right side of one-cylinder pressure close, and all can achieve 784.5kPa; With idle of vacuum meter test fast condition falls left, on the right side of engine is spent into the vacuum of air system, left engine vacuum is spent amount to 60-65kPa, accord with technical requirement, and on the right side of engine is spent into air system vacuum fluctuate between 50 one 53kPa only. Engine spends lower than technical requirement 10kPa into air system vacuum on the right side of. Because,this may be on the right side of engine reachs the passageway taking energy of life before its to have leak into gas branch run, but the part that did not discover any leak via the examination.
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