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MetroMPG · 12-14-2007, 04:48 PM

The theory behind increasing EGR is that it's depleted of oxygen - so it's inert in terms of aiding combustion.

By reducing the amount of oxygen in the intake air, you're forced to run at a wider throttle opening to produce a given amount of power. The ECU will (try to) ensure you don't run rich in the leaner air with feedback from the o2 sensor.

The wider throttle opening should reduce pumping losses and increase efficiency.

Assuming... the added heat in the EGR doesn't reduce dynamic timing.

12-14-2007, 04:48 PM	#38 (permalink)
MetroMPG Batman Junior Join Date: Nov 2007 Location: 1000 Islands, Ontario, Canada Posts: 22,534 Blackfly - '98 Geo Metro Team Metro Last 3: 70.09 mpg (US) MPGiata - '90 Mazda Miata 90 day: 54.46 mpg (US) Appliance car Mirage - '14 Mitsubishi Mirage ES (base) 90 day: 57.73 mpg (US) Thanks: 4,082 Thanked 6,979 Times in 3,614 Posts	The theory behind increasing EGR is that it's depleted of oxygen - so it's inert in terms of aiding combustion. By reducing the amount of oxygen in the intake air, you're forced to run at a wider throttle opening to produce a given amount of power. The ECU will (try to) ensure you don't run rich in the leaner air with feedback from the o2 sensor. The wider throttle opening should reduce pumping losses and increase efficiency. Assuming... the added heat in the EGR doesn't reduce dynamic timing. __________________ Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata Honda mods: Ecomodding my $800 Honda Fit 5-speed beater Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage. Ecodriving test: Manual vs. automatic transmission MPG showdown EcoModder has launched a forum for the efficient new Mitsubishi Mirage www.MetroMPG.com - fuel efficiency info for Geo Metro owners www.ForkenSwift.com - electric car conversion on a beer budget