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Old 01-30-2010, 08:30 PM   #10
4th Gear Member
Join Date: Oct 2005
Location: Toronto
Posts: 697
Originally Posted by nachos23 View Post
actually it's other function is to help heat up the catalytic converter to operating temp more quickly. By restricting exhaust gases, system heats up more quickly. Cold catalytic converters emit more CO2. That's where the eTest might be a concern. If car left cool down before test, it will emit higher CO2 readings (as I understand) until it reaches operating temp.
Dunno who told you this but it's baloney.

The secondary air pump is what heat the cats up upon cold starts. That flap doesn't really restrict all that much. Certainly not enough to heat up the cats. A restriction that far upstream that was enough to heat up cats would be a cause for concern.
'85 325e
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