View Full Version : Fuel MPG better with miles on truck
REDTRUCK05
08-13-2006, 20:17
I should maybe appologize for some negative posts in the past about MPG on my 05 lly. I now have 21,000 on the truck and they are SLOWLY getting better. For anyone out there frustrated with MPG, it does get better. I hope it gets even better, Ha! but, With increased power, comes losses... I guess. My only other issue is the cooling system, Clutch fan...
mcwhitsitt
08-17-2006, 15:02
Glad to hear your comments. I am beginning to get very disgruntled with my '05 dually. 7.5mpg @ 65 mph pulling 9,500lb 5th wheel. 16,000 mi. on odom, Banks air system with predator programmer. Program doesn't matter, economy the same. Empty hwy driving 65-75, doesn't matter, 15mpg. Many times wish I had my '03 7.3 back. Even thinking about selling the Duramax out of sheer frustration. When I first installed the predator on economy setting I noticed the truck computer indicating 22 mpg, was very pleased until I checked the miles vs gallons. Truck computer said I used 18.6 gls, truck took 22.9 gls to fill up. Predator throws truck computer off by at least 25%. Real mileage was 15 mpg. Hope my mpg comes up like yours is apparrently doing.
WILLYD-MAX
08-18-2006, 11:26
Mcwhitsitt..... Give it some time. Also I would highly recommend a good quality fuel additive (FTTP Total Power or Amsoil additive) that should give you a slight gain .5 to 1 mpg. gain and synthetic engine oil and trans fluid.
REDTRUCK05
08-29-2006, 19:29
Glad to hear your comments. I am beginning to get very disgruntled with my '05 dually. 7.5mpg @ 65 mph pulling 9,500lb 5th wheel. 16,000 mi. on odom, Banks air system with predator programmer. Program doesn't matter, economy the same. Empty hwy driving 65-75, doesn't matter, 15mpg. Many times wish I had my '03 7.3 back. Even thinking about selling the Duramax out of sheer frustration. When I first installed the predator on economy setting I noticed the truck computer indicating 22 mpg, was very pleased until I checked the miles vs gallons. Truck computer said I used 18.6 gls, truck took 22.9 gls to fill up. Predator throws truck computer off by at least 25%. Real mileage was 15 mpg. Hope my mpg comes up like yours is apparrently doing.
I first installed the Predator and was not impressed at all. Switched to the edge and was much happier. I did not give the Predator much time. I had the superchips in my 01 Ford 7.3. It was ALOT more resonsive, but I do think the Duramax has more in it. I might be wrong but I think it has to do alot with the fact that it is a higher rev engine.
REDTRUCK05
09-19-2006, 21:22
Uninstalled my edge, Installed Hypertech (GIVEN to me by dealer) got instant low 20's mpg! This is DIC readings, waiting to do calcs.
I've been pulling a 28' Gulfstream 5'ver for 2 seasons now with my 03' GMC 2500HD 4 dr, LB 4x4 Duramax, Allison auto. Now, I didn't expect a miracle of fuel economy out of the vehicle when pulling the trailer to begin with. I am running bone stock, except for B-20 biodiesel as often as possible. I change my oil religiously at 3k miles when towing, and rotate at 6k. The only other than stock modification is the K&N panel air filter. I do run a 6+ cetane boost when running bio and during the winter (don't run bio in Michigan winters...).
I usually pull 11.2 - 12 mpg at 63-65 mph. Anything over that and it nosedives into the 9's. 60 mph and below, milage comes up to around 14 mpg on a good windless day. I still say it's all in the manner in which you drive your vehicle. 21- 22 mpg dry is not an unreasonable expectation. I have done the math time and time again to be sure it was correct, and calculated the error on the computer.
You may be surprized what the change of driving habits might bring to your fuel economy. I did that with my first diesel, and noticed a large difference right away. It does make sense.
My experience is very similar to Mcwhitsitt's...LLYs suck more fuel. I have the Banks intake and cat-back exhaust and a Predator. Power is awesome, but mileage sucks no matter which program I use, including stock. Empty 70-75, I get 16, towing only 7500 lb camper I get 10. Predator throws the DIC way off. Small tank only makes it more frustrating.
What I need help with is the EGTs--what is a safe max? I've read that 1365 continuous and 1435 max for up to 5 min is ok, but I can't keep it that low. Keep in mind that in Idaho there are hills and mountains to climb--stock program doesn't have enough power, and EGTs still get to 1400. Predator 40 hp tow tune gives the power, but EGTs are over 1400 if I'm anywhere near 65 mph, let alone going up a hill which will quickly push to 1500 if I don't keep a close eye on it and back off. How do I get the EGT down without going 50 mph?
Thanks, Al
05 LLY CC
Oh, I forgot to mention that my truck has 32K miles on it and is fully synthetic--Amsoil in engine, tranny, and both diffs. I can live with the mileage while wishing it was better, but am worried about the high EGT.
Alpo
JD_Diesel
10-09-2006, 19:55
My MPG really sucks too. Some day it really pi$$ me off Average is 10 to 12 no hot rodding. and when I do hot rod on the lower side of average. Average MPG when towing is 8 to 10 max speed 62. have tried it in tow haul and non tow haul dont make much differance in MPG. And am amsoil front to back. Have 27,000 on truck now. At this rate my sub 454 3/4 ton was getting better MPG all around then my D Max. Not real happy with that part of the truck, but would not trade for anything else. Oh yeah the small tank reallllllly sucks bad I would like to meet the nimrod that decided to put that small of a tank on a truck that they knew was going to used to tow and haul heavy loads I got some thing for that rocket sicentist.....JD
DmaxMaverick
10-09-2006, 20:54
My MPG really sucks too. Some day it really pi$$ me off Average is 10 to 12 no hot rodding. and when I do hot rod on the lower side of average. Average MPG when towing is 8 to 10 max speed 62. have tried it in tow haul and non tow haul dont make much differance in MPG. And am amsoil front to back. Have 27,000 on truck now. At this rate my sub 454 3/4 ton was getting better MPG all around then my D Max. Not real happy with that part of the truck, but would not trade for anything else. Oh yeah the small tank reallllllly sucks bad I would like to meet the nimrod that decided to put that small of a tank on a truck that they knew was going to used to tow and haul heavy loads I got some thing for that rocket sicentist.....JD
There's no excuse for that. Your best unloaded mileage is worse than mine, towing a heavy 5'er. Something is very wrong.
Kind of a reach, but try this.....
Dump the synthetic engine oil, and use Delo or Rotella (non-synthetic) for a few changes. Drive the snot out of it, towing and not. From your report, you won't lose much in the way of mileage anyhow. It is possible the engine isn't broke in. With those miles, it's possible the engine hasn't worked hard enough to get things wore in. After you have about 6-10K more on it, switch back to synthetic. Once parts like rings get seated wrong, it's a real bear to get them right. You also might give JK a call. He has some EFI Live economy tunes that could help, but try the oil and "drive it like you stole it", first.
There's just no reason for a healthy truck to get such poor mileage.
JD_Diesel
10-09-2006, 21:17
DMAX first 10,000 miles where non syn, I don't change to syn until I have 10,000 mile on any of my equiment. That's been my way for 20 years. I would say 10 to 12,000 mile where towing heavy. First trip to oregon with 5er weight was 21980 pounds combined. Truck had 2500 mile's on it and drove hard. I don't baby my trucks. might have to try your idea about dino oil. Thanks JD
ALPO,
I had the same high EGT temps with the Predator.
I think the problem is a sleepy turbo on the '05s.
Contact John at Kennedy Diesel; he has a simple devise to wake up the turbo.
With it and the Predator set at 40HP for towing 14k my exhaust never gets above
1000 deg., post turbo.
CHRISTO.
I'm a reformed fuel and lubes engineer. Synthetic motor oil in a diesel is a simple waste of money, because one changes (or should) the engine oil before the additive package is depleted. The base stock is by no means in danger unless the additive package is toast, and by then synthetic base stock is doomed as well.
Rotella T or Mobil DelVac are at the top of the list.
Running on the Interstae does very little damage to engine oil. Cold starts and cold idling do. With a diesel (or gaso engine, for that matter) "warming 'er up" is not the way to go. Once the sucker is firing on all cylinders, GO! Don't horse it, but get that thing up to operating temps as quickly as possible...
Bernie Klashinsky
10-13-2006, 21:33
Hi there:
I have never posted a reply on this forum, but I have been reading a lot lately about mileage. I am a Canadian, so of course my mileages will be for the larger Imperial gallon (4.5 litres compared to 3.76 litres for the US gallon).
Our 2003 Sierra 2500 HD Crew Cab short box is ABSOLUTELY stock. I was an engineer in the Navy and believe one shouldn't fool around with perfection.
We pull a 28 foot, 2005 Outback fifth wheel that runs about 9,800 lbs when it is road ready. I am 67 years old and I have lived this long by being very practical and of course very careful. In the last 13 years we have travelled about 200,000 miles around the continent, visited 38 states and all 10 Canadian provinces. We do all our towing at 55, and my "Max" loves it, and our mileage has been as high as 16 mpg on the flat plains and with no head winds. When we climb the mountians between British Columbia and going south to California and Arizona, well of course they drop down to 11 or 12. As state governor, Arnie is pushing the max of 55 for all vehicles towing in California, and lately there has been zero tolerance on speeders. This summer we found the same in Iowa. No problem for us, we love to enjoy the scenery, and at the end of the day, we feel so much better. We have a rule in our rig - no more than 200 miles a day, as we used our club camping membership to the fullest and pay just $6 or $8 a day for camping.
I have had 28 miles to the gallon here at home, empty, and normal running from where we live into the city we are getting 23 to 24 in the summer with no AC, and down to 21 in the winter months with our rains, wipers, heater on etc.
Our trip this year took us from home here in BC south to Arizona then east to the Canadian Maritimes and then back in September for a total of 10,500 miles. Our overall average for the whole trip was 13.9 mpg.
We have 58,000 miles on Max now, and I love it more each day. I keep dreaming about winning the lottery so I can buy a new one with the 6 speed tranny.
I do all my towing in cruise control, except for the very steep climbs. I use the tow/haul mode when starting out from a dead stop, when doing moderate climbing, and of course when going down hills. In my opinion, while they do work, an exhaust brake is akin to shoving a spud up your tail pipe. I have talked to some Duramax owners that have been scared by their tow/haul going down the mountains. If your RPM gets up around 3 grand, simply step on the throttle to make the Allison shift back up, or take it out of tow/haul.
I am not a reckless driver, don't show off when towing, but sometimes I do brag a wee tad. I love it when I sit back and relax and let Max in cruise take us up the mountains and leaving all those poor Fords and Dodges over at the side of the road spewing out black smoke and probably down in 2nd gear.
Up here in Canuck land we are curious as to what is going to happen when we travel in the US and find only bio diesel, will we have to start using fuel additives?
In conclusion, I know a lot of Duramax owners don't have all the leisure time like I do, but I think the only way to get the high numbers for mileage is to keep the rig below 60 miles per hour. I never trust the average or instant mileage readout on the DIC, but calculate mileage the old fashioned way. We also hate the small tank, but we also have a rule - we only burn the top half of the tank. When we hit half, it is time to bail out.
In the Navy we used to say that most diesels could be maintained with a sledge hammer and a crow bar, they just need two things; clean air and clean fuel.
On the clean air subject, here is an interesting fact. A fram air filter up here costs $26 at an auto supply store. When we travel in the US, we hit good old Wally World and buy them for about $11.48 (in Oregon, no tax). When I pull out the filter it is stamped with, you guessed it, "MADE IN CANADA". I thought NAFTA was supposed to pull us all together, but I guess not.
Sure love reading all the good things about Duramax. We love ours and use it only for towing, too big to get around the small parking spots here in our city. My sweetie has a 1992 Toyota with 145,000 miles on it, and we use it for jigging around. But sure miss Max, and I usually take him out for a run at least once every two weeks.
Bernie "Canuck"
JD_Diesel
10-14-2006, 06:38
christo what year is your truck. I have had mine set like you said with stick and pred setting 40. And have had very high exhuast temps ? JD
JD_Diesel
10-14-2006, 06:40
Bernie Great post you are right about the 55 thing. It really blows me away when I see these nuts going 70 80 mph down the highway with heavy toy hualers. Can't wait to get up into canada and do some exploring. My granddad and grandma traveled for 25 years in the us and canada. my grandad was from canada and my grandma was from mexico. I know what a combo. Not real interested in going to mexico to crazy there for me. JD
J.D DIESEL
It's a 2005.
Put John Kennedy's Boost Stick.
https://www.kennedydiesel.com/
CHRISTO.
Thanks, Christo. I'll give the boost stick a try. Alpo
doncannon
11-09-2006, 22:55
hello all,
Mcwhitsitt: what kinda mileage did the '01 Ford 7.3 get?
thank you,
Don
Good description on the Duramax MPG topic. I bought the 06 LBZ 4x4 reg. cab long box 1 ton model. I picked it up 7-1-06 and could not believe the power in this truck and the seamless shifts on that 6 speed. The tranny option on downshifts with tow/haul saves brakes alot. After 4 months I have finally found this area for chat on the subject. Your story says alot of what I have experienced. I live at 4500' elevation CO. and travel alot of wide open country which allows me to put my speed anywhere I want to check the MPG on it. MY average low is 20/21 town type driving and open road is 23 mpg. I have beat that once but you would laugh if I told you my max MPG it was outstanding. I now have business in the mountains for the next 3 months so I will have more numbers to look at from that commute. I have only changed my exhaust the rest is stock. I know there is more in this MPG to get if I can figure out the interface on the fuel injectors signals. The ECM has all the signals and I want the EGT and fuel/air spec averages collected from a monitor in a cycle of drive time to work on this. It's sure challenging to try and get the best mileage with a personal contest constantly for me. I don't bore anyone with my talk I just do it on my own with both my vehicles. We have a Jeep Liberty CRD 06 too, it turns in magnificent numbers with only the same exhaust change I discovered custom made in our area. Comes from a maker who knows so much if you just ask a question he can explain the process and help make your system prove up maximum output and economy when you want either as needs change. Lots of other men talk about all the changes they make and still get just such and such MPG from our stock setups we are paying out better than any aftermarket so far as I see for my needs. These guys are spending many thousands trying all the aftermarket items but they have alot of fun making big power and that takes big fuel just a fact of life. At least I have heard your story and know another MAX runs similar to mine at times. My numbers are done by hand just habit. I hope you have a good winter in the upper Lats. Out....
Good description on the Duramax MPG topic. I bought the 06 LBZ 4x4 reg. cab long box 1 ton model. I picked it up 7-1-06 and could not believe the power in this truck and the seamless shifts on that 6 speed. The tranny option on downshifts with tow/haul saves brakes alot. After 4 months I have finally found this area for chat on the subject. Your story says alot of what I have experienced. I live at 4500' elevation CO. and travel alot of wide open country which allows me to put my speed anywhere I want to check the MPG on it. MY average low is 20/21 town type driving and open road is 23 mpg. I have beat that once but you would laugh if I told you my max MPG it was outstanding. I now have business in the mountains for the next 3 months so I will have more numbers to look at from that commute. I have only changed my exhaust the rest is stock. I know there is more in this MPG to get if I can figure out the interface on the fuel injectors signals. The ECM has all the signals and I want the EGT and fuel/air spec averages collected from a monitor in a cycle of drive time to work on this. It's sure challenging to try and get the best mileage with a personal contest constantly for me. I don't bore anyone with my talk I just do it on my own with both my vehicles. We have a Jeep Liberty CRD 06 too, it turns in magnificent numbers with only the same exhaust change I discovered custom made in our area. Comes from a maker who knows so much if you just ask a question he can explain the process and help make your system prove up maximum output and economy when you want either as needs change. Lots of other men talk about all the changes they make and still get just such and such MPG from our stock setups we are paying out better than any aftermarket so far as I see for my needs. These guys are spending many thousands trying all the aftermarket items but they have alot of fun making big power and that takes big fuel just a fact of life. At least I have heard your story and know another MAX runs similar to mine at times. My numbers are done by hand just habit. I hope you have a good winter in the upper Lats. Out....
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