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Old 01-26-2013, 09:06 PM   #33
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Join Date: Apr 2010
Location: Murrieta, CA
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My Ride: '94 325iC & '00 323i
Originally Posted by glhx View Post
could this simply be a vacuum leak. o2 is reading air in the system (reading a lean condition) ....reporting it to the adjusts the injectors to run rich. this extra air being down stream from the maf sensor could do that.
What a minute!

Air that leaks into the system (intake) after the MAF is an unknown, and always results in a lean condition. The O2s will report a lean if they cannot call for enough gas to overcome the extra air that is not known.

If the O2s are reporting a rich, then it is not because of a leak in the intake.

O2s report the state of the exhaust. If they report rich, then there is too much gas in the exhaust. If they report lean, then there is too much air. If the O2s are failing, have failed, then there is no way to know that what they report is true or not. If they report rich AND there is an intake leak, then they are failing. They are unreliable at best.
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