1395 miles without refueling

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An interesting thing happened the other day ... I was sent to Gaston, SC to pick up a load of pet food. It weighed just over 40k lbs and was going 1400 mi away to New Brunswick, Canada. My last fuel-up in the USA was at the Dysart's Truck Stop at x. 180 on I-95 near Bangor, Maine. After which I delivered the load to the town of Dieppe near Moncton, NB; returned to Auburn, ME, picked up a load and drove to Guelph, ON - all without refueling. When I rolled into our yard in Guelph, the fuel gauge still showed above the minimum level (above the yellow field but below the 1/4 mark); and I would hear the low fuel alarm if the truck's nose was going up or down on a hill.

All in all I did 1,395 mi and it took 186 U.S. gallons to fill the tanks up at the yard. Which means I did 7.5 MPG! That's real, not the ECM. The ECM still showed the eternal 7.1 MPG.

OK, here's why the fuel mileage was so good. Out of 1,395 miles I did:

- 300 mi loaded with 40k lbs from Bangor, ME to Dieppe, NB (Can.) Huge hills in NB!
- 400 mi empty from Dieppe, NB to Auburn, ME
- 680 mi loaded with ... 1,010 lbs (!) of auto rubber mats from Auburn, ME to Guelph, ON (Can.)
- 15 mi empty from the consignee in Guelph to our yard in the same city.

All this time I pulled a 53 ft dry van and my speed was 59-60 MPH (1,350 RPM). The engine is CAT C15 turned up to max horse power and torque. So, even with a big engine you can get decent fuel mileage if you run slow and have a light load.

BTW, this is my last dry van run, as I'm waiting for the trailer dealer to tell me I can start heading to Missouri to get my Wilson step. They started the production on Aug 10th, and should finish Friday, Aug 14th.

[heavyhaulerss]

I have many times got 7.6 7.8 m.p.g running fron indy to g.r. MI & back. 45,000 wt going up 43,000 coming back. 55 m.p.h in MI. 60-62 in IN. I think the biggest factor was I hauled skidded steel coils up & fire brick back. the loads had no wind resistance. compared to when I hauled plastic pipe, 25,000 lbs 13ft high & got 4.3 m.p.g even though my rpm's run higher than most60 m.p.h @ 1500 rpm's I am still happy with my lil 350 h.p. det. the fuel mileage savings over 10 years has paid for so much. I will also say that hywy tires gave me a lot better m.p.g than my lug's, but the lug tires lasted twice as long, but cost 100.00 more per tire. some react as if I am lying when I tell em my m.p.g. they just look at my cabover truck with over a mil miles & no major work done to it, & they think no way it get's good m.p.g.

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I have many times got 7.6 7.8 m.p.g running fron indy to g.r. MI & back. 45,000 wt going up 43,000 coming back. 55 m.p.h in MI. 60-62 in IN. I think the biggest factor was I hauled skidded steel coils up & fire brick back. the loads had no wind resistance. compared to when I hauled plastic pipe, 25,000 lbs 13ft high & got 4.3 m.p.g even though my rpm's run higher than most60 m.p.h @ 1500 rpm's I am still happy with my lil 350 h.p. det. the fuel mileage savings over 10 years has paid for so much. I will also say that hywy tires gave me a lot better m.p.g than my lug's, but the lug tires lasted twice as long, but cost 100.00 more per tire. some react as if I am lying when I tell em my m.p.g. they just look at my cabover truck with over a mil miles & no major work done to it, & they think no way it get's good m.p.g.

I like cabovers. Too bad Freightliner doesn't sell here the Argosy anymore. I remember you writing about the low weight of your truck that helped you get more loads...

[Rev.Vassago]

I like cabovers. Too bad Freightliner doesn't sell here the Argosy anymore. I remember you writing about the low weight of your truck that helped you get more loads...

I want an Argosy like this: Twins Custom Coaches | Gallery (http://www.twinscustomcoaches.com/gallery.php)

[Copperhead]

Since I disabled the EGR on my ISX, I have consistent mid 7's month after month, pump to pump. The ECM is showing high 7's most of the time. My ISX seems to absolutely love 1400 RPM, fine balance between power and mpg. 1400 puts me on 64-65 with 3.42 rears and a 13 spd in an International 9400. I pull an average of 38,000 payload. Mostly operate PA - CO area, usually staying north of I70 / I44. Lot of two lane running, and if 55 speed limit, I will drop to 12th and run about 1450 rpm which puts me on about 58 except in Illinois where I will consistently run in the top hole at 1300 / 60 mph. I rarely operate the engine outside of 1300 - 1500 rpm.

[Rev.Vassago]

Since I disabled the EGR on my ISX, I have consistent mid 7's month after month, pump to pump. The ECM is showing high 7's most of the time. My ISX seems to absolutely love 1400 RPM, fine balance between power and mpg. 1400 puts me on 64-65 with 3.42 rears and a 13 spd in an International 9400. I pull an average of 38,000 payload. Mostly operate PA - CO area, usually staying north of I70 / I44. Lot of two lane running, and if 55 speed limit, I will drop to 12th and run about 1450 rpm which puts me on about 58 except in Illinois where I will consistently run in the top hole at 1300 / 60 mph. I rarely operate the engine outside of 1300 - 1500 rpm.
My ISX is the same way. Anything above 1500 RPM and it just feels like it is screaming.

[allan5oh]

120 gallon tanks like me? I've done 1500 miles a few times.

[BanditsCousin]

I'd like more info on disabling the EGR on an ISX. I just went through my 2nd EGR valve in 4 months on mine. I avg 5.2mpg lifetime avg on mine so far, with 16% idle time and 49.7% of engine run time in top gear (according to my latest printout). I got the Tripac installed about a year ago, so I expect that number to change dramatically since I'm no longer idling. My idle was excessive due to sitting a lot in warm areas, or idling to keep my lil pug cool when loading hhg in areas like Phoenix and Las vegas while I would load hhg for a number of hours.

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I want an Argosy like this: Twins Custom Coaches | Gallery (http://www.twinscustomcoaches.com/gallery.php)

I'd prefer this one. This is a Renault Magnum they make for Germany.

[tracer]

1400 puts me on 64-65 with 3.42 rears and a 13 spd in an International 9400. I pull an average of 38,000 payload.

3.42 ... that's fast .. i wanted to change my rears to that. but with 2,000 torque and 3.73 rears now i'm killing everybody on hills :) but of course everybody passes me on flat.

[tracer]

120 gallon tanks like me? I've done 1500 miles a few times.

i have special tanks ;) the tag on them says, "150 gal US, 142 (I think) usable". Even when I'm totally empty I haven't been able to put more than 180 something gal of fuel in the both. The tanks look clean inside, so I don't know ... they're probably 120 gal, not 150. But 1500 mi without refueling? that's amazing. You probably did over 8 mpg.

[Musicman]

I'd like more info on disabling the EGR on an ISX. I just went through my 2nd EGR valve in 4 months on mine.

Agreed. Definately would like more info on this as well. What effect does it have on the catalytic muffler, or do you remove that as well? It doesn't screw with the truck's ECM? I'd think the exhaust sniffers would be sending all kinds of warnings to the ECM.

[BigDiesel]

I'd like more info on disabling the EGR on an ISX. I just went through my 2nd EGR valve in 4 months on mine. I avg 5.2mpg lifetime avg on mine so far, with 16% idle time and 49.7% of engine run time in top gear (according to my latest printout). I got the Tripac installed about a year ago, so I expect that number to change dramatically since I'm no longer idling. My idle was excessive due to sitting a lot in warm areas, or idling to keep my lil pug cool when loading hhg in areas like Phoenix and Las vegas while I would load hhg for a number of hours.

With a cold engine (after it has been shutdown for 6-8 hrs) turn the key to the on position for about 15 seconds (do not start) let the egr close. Then simply unplug it..... Your ISX will run cooler and get better mpg.

[Rev.Vassago]

With a cold engine (after it has been shutdown for 6-8 hrs) turn the key to the on position for about 15 seconds (do not start) let the egr close. Then simply unplug it..... Your ISX will run cooler and get better mpg.
Wouldn't that give a check engine light? Would you have to do this every time the truck is started?

[BigDiesel]

Wouldn't that give a check engine light? Would you have to do this every time the truck is started?

It shouldn't, but it will throw a code. No harm no foul, but the engine needs to be out of warranty from Cummins. Make sure the connectors are taped and secured to keep out moisture and dirt.

[Musicman]

Hmmmmmmmmmm, I think I might try this in the morning. What about you, Rev? You got an ISX you want to try it out on?

[skrissel]

With a cold engine (after it has been shutdown for 6-8 hrs) turn the key to the on position for about 15 seconds (do not start) let the egr close. Then simply unplug it..... Your ISX will run cooler and get better mpg.


Thanks for the info. I will give it a try. Is anyone else running like this? I'm also about to hook up a hydrogen generator on my ISX. I have gained 1mpg with one on my Series 60 in my other truck. Well worth the $.

-scott

[Musicman]

Well, I just tried it. Runs like a charm... bobtailing, anyway. We'll see in a week or so about fuel economy and power. I'm still concerned if there will be any shortening of the life of the catalytic muffler... I've heard they cost around $3000, though I've never had to replace one.

[Rev.Vassago]

Hmmmmmmmmmm, I think I might try this in the morning. What about you, Rev? You got an ISX you want to try it out on?
I do, but I'm still under warranty until next June.

[Copperhead]

I have been running with the EGR in "test mode" (unplugged) for some time now. My latest oil sample came back from the lab... a few points lower iron, lead, etc and WAY less soot... .2 in 25,000 miles without a bypass filter. Even the oil looks cleaner longer, visually. Even on a hot day with the AC on and under a good pull on a hill, the engine rarely exceeds 195F. Fan cycles way less than with the EGR plugged in. ECM shows a mpg average now in the high 7's, but actual pump to pump is averaging around 7.3-7.4 . Throws on fault code, but it just shows up as an electrical disconnect on the Cummins test software. Dealer could care less that the EGR is unplugged and is facinated how well it is working.

[Musicman]

I do, but I'm still under warranty until next June.

My extended warranty just ran out @ 400k, so I figure what the heck. Even if there is no real benefit, the way ISX EGRs have been failing, I'd run with it disconnected just so I don't have to worry about having to repair or replace it.

I religiously track every drop of fuel I buy, so I'll know pretty quickly if it makes a big difference. I can't wait to see how it does when we hit the road in a week.

[Rev.Vassago]

Please post your results. I'm very curious.

[Musicman]

After a little discussion with my local repair shop, which happens to be a Cummins dealer, I'm rethinking this whole EGR experiment. The service manager at this shop is a no BS kind of guy and would not say something simply because it was contrary to what Cummins wants him to say. While Don (the service manager) agrees that disconnecting the EGR would improve fuel economy and make the engine run cooler, he also answered the question I posed in my first post… it would be bad for the catalyst. He said it might be worth taking a $2000 risk (what a replacement catalyst costs) if fuel went to $4 of $5 a gallon and stayed there, but in his opinion at the current price of fuel, the costs associated with the decreased life of the catalyst would outweigh any cost benefit gained through fuel savings.

[Copperhead]

It has been observed that those with DPF's and such are not candidates for unplugging the EGR. Seems like the results are not good since more of the electronics are talking with each other. Since there is no "catalyst" on a pre '07 engine, it is a non issue. I assume by "catalyst" you meant a DPF. They are not the same thing but oh well. Some are not able to do it for other reasons. We all know that Volvo's will throw a CEL if you just scratch your rear in the wrong way. Seems some with Cummins in Volvo's get CEL and other events when unplugging the EGR. I think there are factors like which software version is in the ECM, which make/model the engine is in, etc that might make for some not being able to put there EGR in "test mode". It's a hit or miss proposition. It just has to be tried to see if it works out.

No experience with DPF's, but on the surface it would seem that a DPF would be better off without EGR. There is less soot generated by eliminating the EGR and therefore it would seem that this would cause fewer regens and cleanings of the DPF. But the engineers have created a nightmare of electronics and interactions going on. I am getting soot levels in my oil that rival those that are running bypass oil filter setups. My last oil sample's soot level was around .2 ppm after 25,000 miles. My oil isn't getting black near as soon as before... almost like when I had a N-14 in the 90's. I can run several thousand miles after an oil change before the oil starts to blacken up.

But from a cost effective standpoint, I am not sure that getting almost 1 mpg better fuel mileage, regardless of fuel price, is not a good thing. And since one has virtually eliminated the EGR and cooler issues on the ISX (especially the pre '07 that had the cooler and EGR on the hot side of the engine), just more rediculous things to not have to replace. I realize that a shop manager has no investment in my truck and therefore, it is not his money heading out the stack. But the shop manager at my dealership has no problem with me doing this to my ISX. He, and the shop foremans, are actually captivated by the results I am getting.

I also understand how some may be a little hesitant in doing this for fear of screwing up. For those, I have no problem if they chose not to. Each one has to live within their own comfort level. I have been known for sticking my neck out and getting whacked with a 2x4. But I still am willing to try some new things. On this issue, it has been a win for me. Probably just dumb luck.

[Copperhead]

Forgot to post how it was recommended to me by a Cummins tech to do the unplug thing...

Let the engine sit long enough to get totally cooled down, preferably overnight. Then turn the key on without starting the engine. Leave the key on for at least 10-15 seconds to make sure the EGR valve stays closed. Then remove the lower 6 o'clock postion plug that pulls out towards the engine block. That is it. Valve remains closed until you happen to plug the EGR back in. There are two plugs going to the EGR, only remove the lower plug. Make sure you tape off the plug and receptacle to keep moisture out.... seems if moisture gets in there, like during a rainstorm, it can throw a mess of fault codes (learned that one on my own).


Results on my ISX in an International 9400i.... before EGR disconnect, mpg average around 6.4 pulling average payload of 38,000 lb. After EGR disconnect, average 7.3 mpg. All pump to pump averages and usually running around 65 mph on the Interstate and doing a lot of two lanes with some good pulls as well. When I can stay out on the interstate and there is a fair amount of easy terrain, the mpgs reach into the high 7's frequently.

[Musicman]

It has been observed that those with DPF's and such are not candidates for unplugging the EGR. Seems like the results are not good since more of the electronics are talking with each other. Since there is no "catalyst" on a pre '07 engine, it is a non issue. I assume by "catalyst" you meant a DPF. They are not the same thing but oh well.

My 2003 Pete 387 with a C15 motor had a catalytic muffler. It was located in-line with the exhaust between the passenger side fuel tank and the drive shaft. It was told that it was unusual for a 2003 to have the catalytic muffler, since they weren’t phased in and mandated until the ACERT 2004 engines, but I had one anyway on my 2003 for some reason. I know Cummins and Caterpillar vary in their designs, but I would assume that if an ’04 C15 has a catalytic muffler that an ’06 ISX would have one as well. I also know that the service manager at my local Cummins dealer seems to think my truck has some sort of catalyst as well. I didn’t get a chance to talk to the mechanic who normally works on my truck though and the service manager could have thought we have a newer truck (most people think its brand new when they see it). I have to admit that I’m new to Cummins and have only owned Cats in the past, but I think I’m capable of distinguishing a catalyst from a diesel particulate filter.

I will investigate further though and if there is no catalyst or catalytic muffler on the truck then I may go ahead with this little experiment. Even if the truck does have some sort of catalyst and its life is shortened, it still may be worth unplugging the EGR. If doing so were to increase our mpg from the current 6.75 to 7.5, it would mean an extra $7,700 a year in fuel savings (at $2.60 a gallon).

[Copperhead]

Yes.... I have heard some Cats have catalysts. But we are talking about Cummins. No such critter on any Cummins setup. Just the DPF's in '07 and above. Catalyst was not dependent on the truck manufacturer, just the engine manufacturer. All emissions requirements are tied to the engine not the truck. Pre '07 Cat Accerts didn't have an EGR even though all the other brands did. This is also why you can order brand new glider kits from FL (Corando and Columbia) and Pete (386)and put, say, a '98 engine in it if you desire. Perfectly legal (except in CA in 2014). That being said, a catalyst reduces CO levels like they do in cars. EGR reduces NOx and in the process, generates more soot because of the reduced combustion temps. If a EGR engine will not hurt a catalyst, then disabling it should make it last longer (less soot to clog it up). Cat used a catalyst on a lot of Accert engines because they were not using EGR and it made the EPA a happy camper. These issues are why Cat is going out of the truck engine business. They can't get around not using an EGR anymore and the other emissions stuff like they could with the Accert. 2010 requirements just flat made it impractical to continue investing R&D into making truck engines. Cummins and Detroit never used a catalyst as they were both using EGR unlike Cat Accert. They just went to the DPF for '07.

Didn't mean to imply you didn't have the knowledge to distinguish between a catalyst and a DPF. Some others have been known to confuse the two. Since the discussion was about the Cummins, I made the mistake that you might have confused the two. My fault.

[Musicman]

Yes.... I have heard some Cats have catalysts. But we are talking about Cummins. No such critter on any Cummins setup. Just the DPF's in '07 and above. Catalyst was not dependent on the truck manufacturer, just the engine manufacturer. All emissions requirements are tied to the engine not the truck.

Didn't mean to imply you didn't have the knowledge to distinguish between a catalyst and a DPF.

I talked to my local Cummins dealer's service manager again today when I went down to pay my bill and he is adamant that my truck has a catalytic muffler. It's been a long time since I've been under my truck and I really don't recall seeing one (at least not one that looks like the catalytic muffler on my '03 C15).

I didn’t take your comment about confusing a DPF with an EGR to be a personal affront – after all, you don’t know anything about me. I didn’t realize however that there was wide spread difficulty in distinguishing between the two, as they are so dissimilar in form and function.

On another note, I reevaluated unplugging the EGR, which I thought I’d already done, but after reading your description of which plug to disconnect, I think I may have unplugged the wrong thing. As I’ve mentioned before, I’m kinda lost when it comes to Cummins engines. Caterpillar always provides a comprehensive manual, but Cummins apparently doesn’t do this, as I’ve been told there is no such thing as an ISX manual. Anyway, I thought I knew where the EGR is located and what exactly to unplug, but I may have wrong. After unplugging what I thought was the EGR, the truck seems to run fine, but now the check engine light is on, so I may have to give up until I can be sure just what the heck I’m unplugging.

[solo379]

It's real easy to find out, just tell them your vin number, and ask them to look for the price on muffler. My ring at around $2500 each (i have 2)

[Copperhead]

On another note, I reevaluated unplugging the EGR, which I thought I’d already done, but after reading your description of which plug to disconnect, I think I may have unplugged the wrong thing. As I’ve mentioned before, I’m kinda lost when it comes to Cummins engines. Caterpillar always provides a comprehensive manual, but Cummins apparently doesn’t do this, as I’ve been told there is no such thing as an ISX manual. Anyway, I thought I knew where the EGR is located and what exactly to unplug, but I may have wrong. After unplugging what I thought was the EGR, the truck seems to run fine, but now the check engine light is on, so I may have to give up until I can be sure just what the heck I’m unplugging.

Including a pic of the EGR on the Cummins (2003-2006) it is on the hot side just in front of the turbo. The pic shows tape over the correct plug to remove. The receptacle that it came out of is just above the plug in the picture. Tape both the receptacle and the plug to keep out moisture.

[Rev.Vassago]

That's the one I thought it was. Thanks for the pic. I'm almost tempted to try it, even though I'm still under warranty till next June.

[Musicman]

Including a pic of the EGR on the Cummins (2003-2006) it is on the hot side just in front of the turbo. The pic shows tape over the correct plug to remove. The receptacle that it came out of is just above the plug in the picture. Tape both the receptacle and the plug to keep out moisture.

That is indeed the very plug I unplugged. Others on here say they haven't had the check engine (orange check mark) come on, but that is exactly what happed after I unplugged the EGR. The truck was cold (hadn't been started in two days) and I had the key in the on position for quite a while before unplugging. I only thing I can't remember at the moment is if I turned the key back off prior to unplugging or not; but after shutting down and restarting a few times, I still have the check engine issue. The truck is still sitting by my shop with the EGR unplugged. Maybe I'll plug it back in, run the truck a while to warm it up and see if the light goes out, let it cool overnight and then try doing this again. If it's going to cause the light to come on, I don't know if this is worth playing with. When I had something really go wrong, I'd never know it.

Thanks, by the way, for the pic you included. I was pretty certain I had the EGR, but as I’ve said 100 times before, I’m a former CAT devotee and therefore a bit of an idiot when it comes to Cummins. At least I know for sure I’m unplugging the correct thing now.

[Musicman]

Well, I tried plugging the EGR back in and then disconnecting it again, but I still have the check engine light illuminating. As before the truck started and idled fine so I decided to use the old electrical tape on the check engine light trick and go pick up a load in Mattoon, IL (about 150 miles from my house).

The truck ran fine going up, but then again I was empty so there wasn’t much demand being placed on the engine. After picking up, I came back to the house because the load has about three extra days on it and can deliver anytime in Montebello, CA. On the way back (grossing abt. 76k pounds) the engine purred right along. The boost gauge was only putting out 2 – 3 lbs in the flats (normally I’d expect at least 5 – 8 lbs with such a heavy load) and the pyrometer indicated slightly lower exhaust temps than I’d expect as well. On the couple of small hills I encountered on my drive, power seemed to be unaffected in either in a beneficial or detrimental way.

Conclusion: We’ll try running with the EGR disconnected out to SoCal and see what kind of effect it has on fuel over the next 2k miles. After that, I’ll reassess whether we’ll continue with our little experiment.

[dieselmanic]

ahmm, I don't know if i would go into CA with a disconnected smog control device. Just saying.

[Musicman]

ahmm, I don't know if i would go into CA with a disconnected smog control device. Just saying.

What they don't know wont hurt me.

[Copperhead]

All you have to say is if they check it is that "the darn plug keeps coming out of the EGR and I am not a certified Cummins tech, so I'll have to get it in a shop as soon as I can". Or you can tell them that Cummins has put it in "test mode" and doing a running analysis on the engine. Better yet, don't say a thing and I'll bet they wouldn't even know it. Those guys are not firing on all thrusters anyway, and I would bet that a lot of them couldn't find the EGR on the engine if you asked them where it was. You give CARB too much credit.

[Musicman]

Well, 7k miles driving with my EGR disconnected has yielded the following:

-- there is an improvement in fuel economy, though the biggest increase (perhaps as much as 20%) seems to be with loads under 30k lbs or so. With heavier loads the mpg increase has been about 5 - 10%.

-- the truck runs much cooler

-- boost and pyrometer readings are lower

-- engine noise seems to be reduced

-- my "check engine" light has remained on from day one, but other than that the trucks runs as good as ever

[solo379]

1859 miles. Fill up 234 gallons.....

[Musicman]

1859 miles. Fill up 234 gallons.....

14526 Miles 2095.058 Gallons = 6.93345959873188 MPG

We have been running heavier freight than normal recently, so I think the numbers are a little less than they would be if we have been running what we normally do. We had three loads totaling over 5k miles that had us grossing 79k + and running into some pretty nasty winds on I-40 and I-10. Our average loads are more in the neighborhood of 20k – 30k lbs, so looking at the data from those loads, our average mpg goes up to about 7.5, which makes me ecstatic. Over the 225k miles we’ve had this truck, we’ve averaged 6.72 mpg, so even 7 mpg is a welcome increase. I’ll be interested to see our oil analysis when it comes back after our next PM.

[Scottt]

I was cruising down the boring highway 54 in kansas with 4 trucks and we got to talking about fuel mileage and I asked if anyone had heard of unplugging the EGR on a Cummins.

A driver that hadn't been talking chimed in laughing and said his shop recommended it but he said they went a little further. He said his shop brazed his EGR shut so he didn't have to unplug it.

Is that possible??

[Rev.Vassago]

I was cruising down the boring highway 54 in kansas with 4 trucks and we got to talking about fuel mileage and I asked if anyone had heard of unplugging the EGR on a Cummins.

A driver that hadn't been talking chimed in laughing and said his shop recommended it but he said they went a little further. He said his shop brazed his EGR shut so he didn't have to unplug it.

Is that possible??


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

[Musicman]

Please post your results. I'm very curious.

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.

[Copperhead]

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

[rank]

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

[Musicman]

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.

[solo379]

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

[rank]

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

[jonp]

I have many times got 7.6 7.8 m.p.g running fron indy to g.r. MI & back. 45,000 wt going up 43,000 coming back. 55 m.p.h in MI. 60-62 in IN. I think the biggest factor was I hauled skidded steel coils up & fire brick back. the loads had no wind resistance. compared to when I hauled plastic pipe, 25,000 lbs 13ft high & got 4.3 m.p.g even though my rpm's run higher than most60 m.p.h @ 1500 rpm's I am still happy with my lil 350 h.p. det. the fuel mileage savings over 10 years has paid for so much. I will also say that hywy tires gave me a lot better m.p.g than my lug's, but the lug tires lasted twice as long, but cost 100.00 more per tire. some react as if I am lying when I tell em my m.p.g. they just look at my cabover truck with over a mil miles & no major work done to it, & they think no way it get's good m.p.g.

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.

[jonp]

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.

[heavyhaulerss]

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.

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.

[allan5oh]

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.

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

[jonp]

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.

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

[jonp]

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

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.