[razor02097]

Originally Posted by christofoo

Emissions suffice to explain why DCD is not done at the factory. This was posted in #179 by Old Tele man:

http://www.epa.gov/otaq/consumer/devices/511817.pdf

I don't think so. If it were emissions then DFCO wouldn't have been used. There is no way to accurately measure the efficiency of the engine when pumping pure air through the exhaust in an engine running state. That is why variable displacement engines physically hold the exhaust cycle so when the cylinder is active again it can expel the exhaust and intake air and fuel.

Think about it the O2 sensor senses O2. You pump ambient air past it and it will swing crazy lean. The ECU responds by adding fuel to that bank.