It is possible, and would achieve the same results as unplugging it. It just eliminates the possibility of undoing it.

Okay, it's now been 31,279 miles since unplugging the EGR. In that time the truck has consumed 4403.949 gallons of fuel, yielding an average of 7.10267 miles per gallon. Prior to unplugging the EGR, I had put 229,076 miles on the truck and used 34,141.604 gallons of fuel, yielding an average of 6.70959 miles per gallon. This demonstrates an increase in fuel economy of 5.858% with the EGR unplugged. That may not sound like much, but so far the increased fuel economy has saved me $646.25 in fuel in just the last 6 weeks. If fuel prices (and fuel economy) remain the same, I'd save about $5,600 over the course of a year. That's like getting my primary liability insurance for free.

I have not had a chance to run an oil analysis yet, because I was in the middle of a change cycle when I unplugged the EGR, but I will say that with 20k miles on the oil I have in the engine now, it looks remarkably cleaner and thinner.

It’s also amazing how much cooler the engine runs. I’ve had several opportunities to drive in 100+ F temperatures and the engine fan rarely came on, even on small grades.

Just had my truck into Cummins for warranty work... leaking front engine cover. Had the EGR unplugged like normal. They could have cared less. Later the tech plugged it back in (required to check and plug in if engine coming in for warranty work), but watched as I unplugged it before leaving and he didn't seem concerned. Service manager acted like it was no big deal and was common knowledge. Now, it might be the particular Cummins shop you go to, but I am not getting the impression that they really care about unplugging the EGR even under warranty.

Last two loads of fuel:

1085 miles, 137.9 gal, 7.86 mpg

1417 miles, 186 gal, 7.62 mpg

do any of you guys that are unplugged have a DPF?

I don't, but I'm thinking that doing this with a DPF would be a very bad thing... but I could be wrong.

Clinton, NJ to Laredo, TX...no refuel.

yeah. I wonder. anyone?

I hauled a load of steel casing pipe for oil drilling from Fontana, CA to near Baton Rouge, LA and got a little over 12mpg. The route is mostly flat and the wind just passed right through the pipes. That was with a Detroit at 435hp. Hauled several of those loads but that was the only one that got over 10mpg. I ran about 60mph and never idled.

This is an interesting thread but could someone answer a stupid question? I havn't seen an explanation as to why unplugging the egr would raise the fuel mileage.

the pipe I used to haul was plastic. 13 ft tall & the entire top had to be tarped. it felt like I was pulling an open parachute down the highway.

I can answer that. It will take a bit of history though.

In 2003, the OEM engine makers were required to reduce the NOx produced by the engine from 4.0 grams per horsepower-hour to 2.0 grams power horsepower-hour.

Everyone except cat decided to go with EGR. EGR reduces NOx by diluting the oxygen content in the air entering the engine. Exhaust has less oxygen, therefore the nitrogen thins out the oxygen. This reduces "peak" combustion temperatures, which reduces NOx production. The problem is, it also hurts fuel mileage and actually increases PM if you don't do anything else.

So the way they introduced EGR is by increasing the back pressure before the turbo with a variable geometry turbo. The "variable" is NOT to decrease spool lag, but rather to increase back pressure. Attached to the exhaust manifold is an EGR valve and the EGR system.

When they want to increase EGR flow, the EGR valve opens and allows exhaust to enter back into the engine. The problem with this, is it bypasses the turbocharger. So the theory is by "shutting off" the EGR, you are:

1) Increasing exhaust flow to the turbocharger, because there is no bypass

2) Increasing the oxygen content of the air going into the engine

oh yeah. Hauled a ton of that stuff although I just smoke tarped it.

Ok, so by increasing the O2 you get a better combustion with the fuel and a higher fuel mileage as a result. I remember that whole thing and cat going its own way.

Hey, Tracer, beat this! 1627 miles, 197 gallons, roughly 8.25 MPG! At the pump!

How's that possible?

I think Solo runs dry van in the Ohio area. I can see him hitting that figure through a few ways.

65mph speed limits, relatively flat demographic, truck maintenance.

Other factors woud be load weight, idle habits, and length of hauls.

Between OH and NY mostly, 45% of my mileage comes to PA, did you see a lot of "flats" there? I also ran a lot of 2 lanes, and should i mention NJ, NYC traffic? But yes, most of the times, i'm pretty light....

Never seen a hill in PA. And never once got caught in any kind of traffic in NJ. I cruise right up 95N and over the GWB at 4pm all the time :)

Solo, you've mentioned you specs before, but tell us again. I know my T600 is specc'd a lot differently, and mine not so much in favor of mpgs! I can get close to your mpg empty at around 43,000 (hhg wagons are heavy).