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Old 11-20-2013, 05:34 AM   #17
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Join Date: Mar 2005
Location: Portland Or
Posts: 2,666
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Is the CAT still intact? The matrix can break and rotate in the can causing back pressure and other fun.

A knock usually sounds loud and harsh, ball peen hammer on concrete .. Ping is lighter and more broad band across the RPM range. Excess back-pressure can create excess pressure in crankcase as well...

Dave - PDX
1995 318ti - Active Black and Tan.
2005 330xi - Mtech 1 - 6spd - Orient Blue/Black
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