Symptom: a the 2011 Shanghai GM Buick LaCrosse sedan ( furnished with 2 .4 LLAF engine ) , the cumulative traveling about 40,000 krn. Driver to mirror the Odometer Tacho Pro car 2 days ago if your highway feels weak acceleration , the engine sounds muffled , engine failure during normal driving and idling lights sometimes flicker. Then traveled to an email finder service station for repair , carried out injector failure , as a result of service station without accessories , so he continued to travel a lot more than 500 krn, and also found fault occurred because the emergence of the high fuel usage of the vehicle .
Troubleshooting : After receiving your vehicle and found the auto engine fault lights lit immortal, engine idle shake obvious. With fault detector test , autologic collect fault code has : P0300 eleven engine misfire ; P0303 eleven 3-cylinder engine misfire ; P0172 eleven high profile adjust the fuel system . Look at data stream is then found that long-term fuel trim is -30 % , 3-cylinder misfire frequently found as soon as the inspection .
Then depending on the obtained three read fault codes and data flow analysis of vehicle malfunctions. From the 3-cylinder engine fire to fire frequently , volvo vida and to adjust the fuel system high profile , coupled with high fuel consumption , and engine shaking phenomena such speculation, ought to be 3 cylinder misfire frequent adverse work of the cylinder , the engine power down, how the focus should be around the impact of three-cylinder misfire might be detected for every single element . Measuring ignition coil resistance , normal ; observe spark plugs, basically normal, but to make sure , or will it be a better ; 3-cylinder cylinder pressure measurement , every in the other cylinder isn't any positive change . Read the suspected point 3 cylinder injector is faulty. Detection of 3-cylinder injector resistance , in line with the requirements of maintenance data , so as to secure the trial after his replacement, engine working conditions improved slightly ; observation data stream , then your long-term fuel trim value is -5% , but in the engine after running about 5 min, the engine idle shake intensified. Until then view the info flow , long-term fuel trim value reached 25% , and 3-cylinder misfire again now , but also with a small two -cylinder misfire phenomenon . This fault diagnosis , fault detector information provided has become helping us . So timely adjust their thinking , provide information from the data stream query again . After careful analysis, long-term fuel trim values are actually high , should also be excluded right away mixture. Check the tightness on the intake system , check the vacuum hoses for cracks , distortions and connections ; then confirm the air conditioning filter or without fouling , clogging the intake manifold , throttle body or without blockage , the results in the inspection items were normal. Confirm the intake manifold absolute pressure sensor parameters camp , but meet the requirements ( standard importance of 19 kPa-42 kPa). Suspected injector leak , causing excessive gas mixture , however the injector was tested , no failure. Finally, only the remaining crankcase through Phoenix and fuel evaporative emission control system is not checked . Then find along the crankcase ventilation hose leak , when checking the oil from the crankcase oil discovery , the upper limit oil level more achieable than the predetermined (FIG. 1 ) , and also the more dilute the oil , gasoline that has a strong smell ( crankshaft box oil level is high , icom bmw resulting in increased effectiveness against rotation with the crankshaft , the driver will be reflected inside sound muffled engine running phenomenon ) .