MadMav

Picked up my new 08 Mega Cab Dually with 19 miles on the ODO. Had a drive of 1200 miles to get it home. Drove the first tank with the EGR plugged in and averaged. 16.2 on the overhead, and 15.4 hand calculated(did not know exactly how full the dealer had it filled). Did the next tank with the EGR unpluged. Got 16.0 on the overhead and 15.8 hand calculated. Plugged it back in after that, and the check engine light went away after about 15 key cycles. Never felt any more power or rough idle/running.

Why did I not get any benifit from unplugging, and anything but a check engine light???

Mav

Dodgezilla

Hmmm, How fast were you going? Was the speed the same during both legs? My mileage went up immediately on the OH and hand calc'd when I unplugged mine....
If I drive too fast, even now, mileage will stink....

mr. ed

I'll make a rough guess. Perhaps you have to wait until the engine is broken in, many 1000's of miles from now. Just a guess, though.....

MadMav

Speed was 65-80 during both runs. Pretty average run really.

Mav

ron b

Comparing mpg on just 1 tank to just 1 other tank is meaningless. There are too many variables, the most misleading being the amount fuel that can be filled into a full tank. This can vary by 2 to 3 gallons depending on speed of fill up and level of the filling area. Even if you fill your tank until clear diesel overflows it is possible to add an additional 3 gallons by parking on a slope and pouring the diesel in slowly.
If you want realistic and useful information your calculations should be derived from data collected over several thousand miles.

MadMav

That is the oposite of everthing I have read and learned about the EGR unplug. Everyone says the difference is instant and readable. And, the overhead does not care if the tank is full or not, it measures the mpg other ways. There should have been a reading change in that if the unplug was working.

Mav

ron b

I agree with you about the overhead I believe it is more accurate then hand calculations over the short term.
When I unplugged my egr I used hand calculations over 4,000 miles compared to the previous 4,000 miles with the egr plugged in. Mpg went up less then 1 mpg with the egr unplugged. I did however gain 2 mpg when my dpf was removed previously.
Your results were most likely affected by other factors such as wind and terrain. Would suggest doing a comparison over a longer term. Record miles, fuel, time, type of driving and overhead reading for each fill up.

J3Cub

Did you unplug the Cast Iron unit on top of the Intake Horn?
If you unplug the unit with the cable, on top of the exhaust, you will have problems, and will not get the MPG.
You will need to remove the Butterfly from the intake, if it is not removed, it will close slightly, and give problems, along with decreased MPG.

MadMav

Yes, cast iron unit on intake side. I will try again when the truck breaks in a bit.

Mav

DieselLady

Also don't forget that the computer learns what is happening as it goes. I suppose it is possible that you didn't give it enough time to learn much of anything to begin with. It is possible that your fuel economy will get worse as the computer learns with the EGR plugged in. Then once you unplug it, it will get much better. Just a guess here. Also from what I hear you will not regen when you unplug the EGR. You also will not regen as much when on the highway as it should do some passive regeneration. So it may not help as much at highway speeds as it does around town. I will say though, you will be running a lot cleaner engine.

MadMav

If you unplug it in town, and it doesn't regen, then you are in a world of hurt from what I read. It must regen if getting full, if not then it will have to go to the dealer right? I have about 1200 of 1300 miles on the highway, and have not had a regen yet.....that I know of. And I watch the overhead like a hawk.

Mav

sabercat

does your overhead say when it regens? I have 8600 miles on mine, never saw anything up there. I watch mine like a hawk also. The only clue I have is when the mpg drops from say 20, down to 14-15 mpg. does that for a bit, then pick back up. I thought maybe that was regening then. Thanks

Dodgezilla

Well, I've been dragging my trailer around for the last two days and I can tell you that my towing mileage has not changed any even though my city mileage went way up....

2whistlers

Is there any indicator as to when the truck goes into Regen?

Dodgezilla

Unless you have a monitor that will alert you to a regen then you can really only tell by your mileage dropping drastically or, if your truck is pretty new, you can smell that the exhaust was getting really hot....