GMScott

OK, so I have a little time at home now and after reading all the threads about EGR unplugging and blocking I decided to just unplug mine. 07.5 and I think it has the latest flashes. So the first ride out with the EGR unplugged, of course I get the CEL, I noticed that the overhead liar is up about 4 miles per gallon for AVG m.p.g. I'm not going out on any trips this week so my experiment will only include running around empty and not really going thru a full tank to accurately measure m.p.g.
What I notice on the Insight is that the CmdEGR which I normally monitor is now down to 0.0% where it normally runs @ 94.9%. The manual for the Insight is not clear as to what I'm actually monitoring with the CmdEGR but this has been my experience since getting the Insight. It usually reads 94.9% until I get on it or towing and pulling hard or downshifting then the CmdEGR reading will come down. Also, when the Cmd EGR starts coming down and the CAT bank temps start to rise above 800* (I don't have the pyro probe) and get to 900* it will go into regen with the Insight flashing a de-soot alarm.
I'm trying to determine the action of the butterfly valve for the EGR. Does it open more while under light load, letting more recycled exhaust back into the intake when the CmdEGR is reading the higher 94.9% and then start to close under power when the CmdEGR reading drops letting less exhaust in?? If so then, this would indicate that just by unplugging the EGR it is now causing the butterfly valve to stay closed all the time. Also, no smoke coming out of the exhaust at all with the EGR unplugged. My truck has smoked since new and can blacken the entire rear quarter panel and the corner of the bumper in less than 1,000 miles while it's working. Also, CAT bank temps which normally run @ 750* are now down to just under 600*. If the butterfly stays closed all the time will this affect long term performance?? It doesn't seem to affect performance now. As a matter of fact the engine sounds even quieter with the EGR unplugged. Will this cause more of soot/clogging problem later on?? Don't want to go back there, seen that before. Removing the DPF, NOX and EGR is not an option for me.
172k miles on the clock.
Thanks for any help in understanding this.

Rrloren

I just filled for the first time with egr unplugged and got 19.2 vs normally 15.5 -15.8. Intake air temps 50+ degress lower and egt's down 100 - 150degrees. Truck still runs great .Over 20% improvement in mpg's! So far no ill effects.

GMScott

Rrloren - I see that you have the Insight too. What parameters do you monitor?? With the mileage that I have on mine, my typical empty fuel mileage is about 18-18.5 @ 70 m.p.h. Towing depends on what I have behind me but will usually run from 9.0-11.5 m.p.g. tops with all other variables such as wind, terrain etc. considered @ 70 m.p.h. I haven't towed with the EGR unplugged yet. Saturday will be my first opportunity to try that, but it will be a relatively short trip so my AVG. m.p.g. will probably not be correct. I'll use the OH liar as a base though to see if there was any improvement with the EGR unplugged.

Rrloren

My overhead is usually .7 mpg off pretty consistent. This time it was only .1 off! Maybe I didn't get as much fuel in as I thought , but I will check a few more tanks.In any case it's at least a 20% improvement in mpg's.
My insight monitors EGT's, Boost, Regensoot , Trans Temp.
I also have another window setup to include Intake air temp,IAT.

skint_back

I am going to get an insight in the near future, I have a question for you guys that have one. When you unplugged the EGR, and got a CEL, does the insight automatically clear the code and CEL go off, or is that only on the attitude monitor? I want to unplug the EGR, but can't stand the CEL.
Thanks.

sabercat

I unplugged mine, at 68mph, got around 19.5-21 mpg, hooked up to my 12000# 5er, was about the same, 9.2-11mpg, thats what I get with it plugged in. MPG empty, seemed to be better, but I only have 7500 miles on mine, probably will get better with more miles.

BroncoHound

From what i understand of the EGR's operation, it pumps nearly 100% exhaust gas back into the engine when at idle. As engine load increases, EGR decreases and more fresh air is put into the engine. That stands to reason why those that work their trucks the hardest do not have as many problems; they aren't getting as much EGR activity. That is also most likely why those of you who have unplugged the EGR are netting exceptional gains in city mileage or empty highway mileage but no real difference in towing mileage; the EGR, when plugged in, isn't pumping any exhaust gasses into the engine while under load so it being unplugged isn't really doing anything in those conditions.

As for the butterfly valve, being completely closed means that 100% exhaust gas is being recirculated into the engine. Being completely open is 100% fresh air. The old flashes in these trucks would, when the EGR was unplugged, completely close the butterfly which, when coupled with an inoperable EGR, would cause a hard code and put the truck in limp mode. The newer flashes now, apparently, have a software change that keeps the butterfly completely open when the EGR is unplugged which is why it is working so well for you guys.

Hope this helps.

Tucana

thanks for the updates, I have noticed a milage increase from 14 ( imperial gallon) to just under 16 while towing a 9000lbs, 28" gooseneck.
I'm thinking I'll make some block off plates this weekend.

GMScott

OK, so I made a short trip to the Jersey shore and brought back an older and heavier 40' TT with the EGR unplugged. Some wind but mostly a cross wind coming back. With a steady cruise-controlled 70 m.p.h. the OH was reading 11.0 m.p.g. Normally, towing that kind of huge brick behind me I would avg. about 9.0 m.p.g. with the OH showing about 9.5 m.p.g. Again since it was such a short trip I'm just using the OH as a base measurement. I like to make my comparisons when I do my usual 1,300 mile round trips, however it does seem that fuel mileage has definitely increased both empty and loaded with the EGR unplugged. Could it be THAT easy?? The question still remains though, what about the long-term affects of having the EGR unplugged?? Also, after clearing the CEL with the Insight the CEL remained off until I restarted. Engine did 1 regen while empty which seemed to take forever, no regen the whole loaded trip back - 100 miles. One glitch though with the EGR unplugged I noticed is a couple of times while backing up and idling the engine would begin bucking/surging. Put it back in park and it would stop and then I could continue backing up without the surging. Small price to pay for increased m.p.g's just took me by surprise each time it happened. Love the clean rear quarter panel too as the truck is still not smoking with the EGR unplugged.

Dodgezilla

I've read of a couple others getting this bucking while backing up. Maybe those particular trucks are having the reverse idle drop a bit more than the majority of the trucks out there and the truck is trying to compensate for it somehow.

My truck did not smoke with just the EGR unplugged...

Tucana

What do yo guys think would be the result of blocking the EGR, but leaving it plugged in. Do you think that when it tried to regen, the throttle butterfly valve would close a bit, and the result of having no EGR gas would be a rational code?

Scotty

With the egr gone, dpf gone, pcv gone and a different air filter I went from 14 hwy and 9-10 city empty to 19.8 mpg hand calculated with a speed of 65 mph. City mpg is in the mid teens now...depending on my right foot. My all time high was 21.8 on the most recent run from Calgary to Pendleton OR. I never saw speeds over 62-63 or 100 KMH. Loaded...my very worst was this trip into an 80 KMH/50MPH head and cross wind...8.7 which is still better then what I was getting on a good day with this truck all stock. My average loaded mg is in the mid 12's and have seen over 14 on a good day with a tail wind during part of it. This is all hand Calc'd. I am only about 3,000 miles away from hitting 100,000 miles...nothing major repaired or replaced...just the engine light for the soft codes of the dpf and egr. I did the dpf at 21,000 miles. I did the pcv at 28,000 and I did the egr at 42,000 miles. Even the intake is cleaner now and the oil stays amber for awhile after a change. If anyone of you took the egr off, you'll know what I mean when I say..."Wow, what a mess in there!" Black soot/carbon lumps. Its almost all cleaned out now. How an engine should breathe.

Scotty

Patriot2500

I just read this entire thread and have one important question to ask all who have just done the EGR unplug. Is this the only mod you did and have seen mpg improvements? If you need to take the truck back to the dealer, could you simply plug it back in a few days before and than take the truck back? Also, do your dealers give you a problem for having the Edge Insights installed? Thanks for clearing up my questions.

Dodgezilla

I don't have an insight but yes most guys are just simply unplugging the connector to the EGR. Some real world testing has proven that you will get some soot past the EGR butterfly valve but even still most guys are seeing at least a 3 mpg gain. I used to miss my 03 SO because of it's great mileage. I don't miss it anymore......
I also must say that some guys have problems doing this and have to plug their EGR back in. Nobody seems to know exactly why yet. You have to make sure you have the latest flash but still there are some trucks that don't like to run right with it unplugged. GMScott's truck bucking in reverse is one of the problems some guys have had. I initially had a very poor idle when starting the truck cold. I have started waiting until the truck goes through it's prestart diagnostic with the five dings before I start the truck. Since doing that I have not had one issue other than a CAT FULL message which I easily cleared and it has not come back yet. I think I just waited too long to clear my codes. It had been over a week....

GMScott

No performance mods other than using a 5.9L drop-in air filter instead of the 6.7L one. (minimal fuel mileage gain) M.P.G. increase is not really verified yet except with the Overhead monitor. Have not been on a regular run to credibly prove a m.p.g. increase with the EGR unplugged. I have the dealer do all my oil changes so will just plug the EGR back in before I go. The Insight will clear any current DTC's prior to a dealer visit. My dealer doesn't really care about the Insight, just have to unplug it before they use their scanner which is very seldom anymore. As a matter of fact, and thanks to DTR, I usually go into the dealer armed with more knowledge than they have on hand!!