EGR - MPG Up or Down?

tune and datalog attached.

2000 gmc sierra 1500, firmed up trans and tcc, disabled egr diagnostics, did away with egr codes, zeroed out the egr spark table adder, added 1 degree of timing, and unplugged egr valve until blockoff plate comes in. (Per customer request, I will be installing that to so they said keep it and drive it)

LTFT are 0-1, STFT are 1-3, no KR, gas mileage seems way down, could just be me. truck runs out fine, and has plenty of power. just seems like its drinking gas now. I've driven it around 50 miles and just about can watch the hand move. let me know what y'all think. Thanks.


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EGR is an exhaust gas that takes the place of some of the cylinder volume so less fuel is required. To make up for it you can play with timing some and even lean it out a little through O2 settings and so forth, but you'll always have a bigger engine without it than with it.

And anytime I'm Logging/Testing I use more fuel than normal driving. Sometimes a lot more.

Oh yes always seems that gas just free flows out when testing. Some timing wouldn?t hurt it for sure It does run a lot better now than before. Thanks

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latest non egr log and tune, finally got the ve table to respond to some changes which seemed to help, along with more timing below 3,000 rpm. everything seems fine. will find out this weekend when i put a loaded trailer behind it. finally got the transmission to respond the way i want also.

My L31 350 got 2-3 mpg worse around town with it on and was far more responsive with it off. With a marine intake, my 500 hp 383 gets better mileage on E85 than the 245 hp 350 did on gasoline.