RUNS OK SLIGHT ROUGH IDLE REPLACED BANK2 UPSTREAM 02 TESTED INTAKE MANIFOLD W/ PROPANE 02 READING GOES UP ON LEFT BANK CANT SEEM TO PIN POINT INTAKE LEAK CAR HAS 50 K ON IT AND IT IS IMMACULATE ANY INPUT WOULD BE APPRECIATED THANKS
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1995 BMW 850Ci
Question: RANDOM MISFIRES
Answer #1patrick mannion from Greg Solow's Engine Room, September 18, 2010, 08:13Master
If you cant' locate the leak in the intake using propane or Chemtool try engine oil in a squirt can it is heavy and apply diligently and listen for the idle to improve. Many automotive repair shops have a machine that generates an inert non flammable low pressure smoke that looks similar to cigar smoke. The intake manifold is sealed off, and smoke is put into the engines intake manifold. The smoke then fills the engines crankcase and if there are any vacuum leaks from gaskets, hoses, or housing smoke emits from the source of the leak.
Does the fuel trim figures show the computer is adding fuel on a scan tool. Look at long and short term fuel trim figures.