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Half power on E39

 
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edjack



Joined: 04 Feb 2002
Posts: 3887
Location: San Jose, CA

PostPosted: Thu Sep 13, 2001 5:14 pm    Post subject: Half power on E39 Reply with quote

Thanks for the input. I'm surprised at this: was the cat damaged by a rock or something hitting it? My 528i still had the original cat, at 230K miles, and still passed the California smog test.

Or did something cause the cat to overheat?

In the Colonies, we have regulations that require emissions control equipment to last (I think) 100K miles. The manufacturer has to replace the stuff that fails for free.

JTYLTK

Ed
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charliesmith



Joined: 07 Jul 2001
Posts: 738
Location: Dallas, Texas

PostPosted: Sat Sep 22, 2001 5:31 pm    Post subject: Half power on E39 Reply with quote

Tony,

What detected the cat blockage was the mass airflow sensor which is located in the intake manifold. A partial restriction in the exhaust system exhaust will increase as exhaust volume increases. This will then cause back pressure in the exhaust system ahead of the restriction and result in the engine being unable to breathe beyond the limits of the restriction. The increased position of the throttle butterfly is academic once the exhaust back pressure limits the engines ability to accept additional intake air volume. The fuel quanity is regulated according to the intake air volume. Thanks for the heads up info. though.

Charlie
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