Increasing EGR flow for better mileage

[Focus-Ak]

Originally Posted by RobertISaar

how does the scanguage calculate fuel economy?

two possible methods, one of which is significantly better than the other but requires more information.

method 1 is estimating fuel injected based on airflow readings from the MAF sensor and the target air/fuel ratio.

method 2 is calculating fuel injected based on injector pulsewidth, RPM, injector flowrate, number of injectors and injection scheme to create a fuel flowrate in gallons per hour.

guess which one is more accurate?

How does the UltraGauge make this calculation?

[oldbeaver]

Originally Posted by Ford Man

EGR flow can definitely have an impact on FE. I bought a new Buick Regal in 1977 and when I first bought it, it had a flat spot during acceleration and was only getting about 12 mpg. One day I was at the dealership where I bought the car and I told the salesman about the flat spot and that I wanted it fixed, so he took the vacuum line to the egr valve off and stuck an eraser from a mechanical pencil in it and put it back on stopping the vacuum from opening the egr valve. From that time on it didn't have the flat spot and the gas mileage increased to about 15-16 mpg. I haven't tried it on a car since, but when the weather warms up and I get a base line mileage I might try plugging the line on my '88 Escort for a few tanks to see what the results are.

How did you measure FE before and after you closed vacuum command of EGR valve?

Old Beaver

[cosmick]

EGR certainly does help MPG when the car has an oversized and overgeared carbureted V8, but I see little hope of running dual EGR valves on anything with any variation of DualJet or Quadrajet, the only carbs to consider for MPG.
When the '80s Camaro guys run the Weiand Stealth-Ram, they have to adapt a Mustang EGR spacer, and these seem stackable. Plus they're offered in sizes from 60 mm, in 5 mm increments, on up. They go between the TB and the IM. Plus you could have more control over the extra EGR valves. But it seems to me that most anyone trying this should be adding them before the TB.
I'll be thinking for myself about before or after the MAF, but this has caught my interest for my now-overgeared 4.8L S-10, even with the turbo.