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The BMW 728iL passenger vehicle idling regime vibration and the acceleration overhaul incapable
宝马728iL轿车怠速抖动及加速无力检修
http://www.enpinfo.com/Engine/Tech/Project/200903/25036.html
Vehicle type: The BMW 728iL chassie type is E38,
the engine model is M52, VIN code WBAGH41010DB88611.
Breakdown phenomenon: According to the vehicle owner reflected, because this vehicle the engine idling regime has carried on the overhaul not steadily in some repair shop, once had replaced the gasoline filter, the spark plug, the ignition coil. Has cleaned the spray hole. The symptom slightly has the change for the better. But had the acceleration incapable breakdown problem. Failure diagnosis: Starting engine test run. The observation idling regime revolution condition, may see the engine vibration the frequency to be very quick, the oscillation amplitude is not actually big, not likely lacks the vibration breakdown which the cylinder creates. Carries on the starting test, although each time the engine can revolve. But felt starts the time is long, showed the breakdown has also had the influence to the engine starting ability. Connects the GTl diagnostic equipment to carry on from the diagnosis, chooses 7 is the E38 chassis vehicle type, the click “the fast test” the key, carries on the scanning to the entire vehicle electrically controlled system. After completing, clicks on “the control module function” key l to select “the DME engine electron in the diagnosis menu to serve controls system M43” the project, the inquiry breakdown information, demonstrated:
008 air flow sensor signal short-circuits or the abruption to the cathode, the breakdown appeared 21 times, current existence.
Carries out the breakdown code elimination function, again starting engine. The inquiry breakdown information, 008 breakdown codes appear once more.
Explained that the breakdown exists really. Continues in” the diagnosis replies” in the function the examination and the air flow signal related data value, as shown in Table 1. Before Table 1 trouble shooting data value:
Data item Actual value Unit Air flow sensor signal 0.03 V Air flow 0 kg/h Engine load signal 0 - Does the acceleration test, in the table each data value fixed motionless, this explained that the air flow signal short-circuited truly to the place, but the engine load signal is calculates through the air flow,
the Okg/h air flow certainly also meant that the engine load is 0.
The overhaul work is carries on the survey to the air flow sensor and the line.
Consults the correlation data, the method is the first click “the function choice” the key, -> “the engine electron serves controls the system” -> “the air feed” -> “the air flow sensor” the function way according to “the power”.
Found the related circuit diagram. Extracts downward the air flow sensor's group of lines plug. With decorates with lanterns and streamers on the eve of the lantern festival surveys the 3rd needle foot voltage. Decorates with lanterns and streamers on the eve of the lantern festival not brightly.
Explanation supply line bad. Opens right flank the engine compartment the electrically controlled box.
Found the engine fuse servo support, on this support has altogether established 5 fuses, carried on the inspection one by one, has not blown a fuse the sign. Inserts the fuse, then surveys the air flow sensor's 3rd needle foot again.
Decorated with lanterns and streamers on the eve of the lantern festival has lightened, explained that the F3 fuse was the bad contact originally.
The starting engine, examines the data value once more, still like Table 1 value showed that looks like must carries on to the sensor and between the DME control module line surveys.
DME control module located at engine compartment right flank in electrically controlled box, the module has altogether used 5 group of lines plugs, what corresponds with the DME control module connected two lines is 52 needle plug needle subscript.
Tears off this plug to carry on the survey, the line does not exist short-circuits or the abruption question.
Opens down the air flow sensor carries on the inspection, the outward appearance has not damaged the sign.
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