something wrong with my truck?

[hex0rz]

ALSO, I have not read Mikes article on MPG's in a while, buuuut, genos garage has a TDR article on MPG's and I think its very useful.

 

http://www.genosgarage.com/GenosGarageTechArticles/TDRBG_FuelEconomy.pdf

[Mopar1973Man]

Like usual some over at TDR has all the fancy test equipment. But they do put out some seriously good information.

[hex0rz]

I hope this does not derail this from the original intent of this thread, but I have noticed a couple things which should tell me about some of what is going on...

 

1. EGT's seem to be around 700, 800 at times driving on flat road with no wind or other factors to cause excessive resistance. This is during the cold, around 20-30's. The egt temp. occurs at about 40-45mph. Going 60, EGT's are around 800 cruising.

 

2. Boost pressures at 60mph, are around 10psi with the same above external factors.

 

I'm basically getting around 4-500 miles per TANK. I know my fuel gauge is off on its reading by about 2-3 gallons consistently, and I have not factored this in when adding 2-stroke. I'm speculating that the ratio is a little high and is helping reduce mileage. I have "purged" the tank of excess oil by running an occassional tank of diesel without any 2-stroke. Does not seem to make a big difference though.

 

Seems like before, I could cruise 60 down the road with the egt's around 6-700 in OD. Taking the TDR article into account, I did some experimenting the other day and I turned OD off when cruising, it went from around 700 in EGT's to about 500 when going about 40-45. Being in 4th reducing my gear ratio, my rpms went up to that sweet spot in the engine and the load is reduced.

 

Its hard to accept this concept, as I was always taught that the less RPM's an engine has, the better the mileage... But as we see, that sweet spot is best for reducing the fuel consumption. Which now reminds me, I've got some acronyms to add, Mike!

[Ilikeoldfords]

Someone told me once with turbo diesels.... The lower the boost and egt's, the better the mileage. Whenever I am trying for high mileage, I just make sure I dont go over 5 psi of boost. Works like a charm. Even running at 1800 rpms, if that  is where the boost and egt runs the coolest for the situation then thats where you will get the best mileage.

[MnTom]

I hope this does not derail this from the original intent of this thread, but I have noticed a couple things which should tell me about some of what is going on...

 

1. EGT's seem to be around 700, 800 at times driving on flat road with no wind or other factors to cause excessive resistance. This is during the cold, around 20-30's. The egt temp. occurs at about 40-45mph. Going 60, EGT's are around 800 cruising.

 

2. Boost pressures at 60mph, are around 10psi with the same above external factors.

 

Seems like before, I could cruise 60 down the road with the egt's around 6-700 in OD. Taking the TDR article into account, I did some experimenting the other day and I turned OD off when cruising, it went from around 700 in EGT's to about 500 when going about 40-45. Being in 4th reducing my gear ratio, my rpms went up to that sweet spot in the engine and the load is reduced.

 

Its hard to accept this concept, as I was always taught that the less RPM's an engine has, the better the mileage... But as we see, that sweet spot is best for reducing the fuel consumption. Which now reminds me, I've got some acronyms to add, Mike!

Your truck has been designed to run approx. 600* with normal driving. It sounds to me that you have a brake (or brakes) dragging. Mine at 60 mph runs at 550* and 0 to 1 psi boost. The reason you saw the EGTs drop when you went to a lower gear is because the engine was pumping more air than it was in a higher gear. My '12 VW TDI has a display that shows instant mileage and it always shows higher numbers in the highest gear it will pull in. That same concept was beaten into my head way back when I drove big trucks 30 years ago.

[Killer223]

I try to stay at 6 psi and under. Even still my egt's are above 600 usually 7??.

As for brakes dragging, they are all brand new, rotors pads refurbished my calipers, greased sliders. They do not drag far as I can tell.

Tires are at 50, have been sense I got the truck. I've had two alignments. Both shops say I need new parts, even the new parts are bad lol. So I'm unsure about that, it drives strait doesn't pull, even tread wear.

So I put my edge on 5, well it's hot unlocked so I dunno what that changes, and scan gauge said I got 19 driving home overhead said 23.

Some questions about timing.

How much does the edge add vs the smarty? I know on a gas Chevy 350 I can run more living at high altitude. I used to run 15 deg.

Would the same be true from a diesel? Couldn't i run more living at higher altitude then sea level. By running more j would run smarty on 3 and edge on something.

What does to much timing do to these? Same as a gasser? Will it ping or knock under heady load or high boost? I could take my turnbuckle off and dial back the edge.

Just kinda thinking out loud here.

[Killer223]

I can't quote on my phone, but you said you run 60 at 0-1 psi boost. My truck does not and would not, my dads 00 power stroke does.

I'm remove front driveline, I think my rear dif has issues. But I don't have to tools to rebuilt.

All new fluids in everything.

[MnTom]

I keep forgetting that I have a modified HX on my truck. I can't remember what was done, but I do recall being told the exhaust housing has been 'upgraded'.

[hex0rz]

Your truck has been designed to run approx. 600* with normal driving. It sounds to me that you have a brake (or brakes) dragging. Mine at 60 mph runs at 550* and 0 to 1 psi boost. The reason you saw the EGTs drop when you went to a lower gear is because the engine was pumping more air than it was in a higher gear. My '12 VW TDI has a display that shows instant mileage and it always shows higher numbers in the highest gear it will pull in. That same concept was beaten into my head way back when I drove big trucks 30 years ago.

Well, thats a tough one to put a finger on. Within the 2nd year of ownership, I'm into my 3rd year now, I replaced all 4 corners with new brakes and hardware. I fully redone the rear brakes. Shoes, drums, springs, etc. and new wheel cylinders.

 

Then I just recently put new calipers on the front. So, the only thing I suppose it could then be is improper adjustment of the rear brakes? I'm hoping its something simple that has been overlooked. In which case, I need someone to make me dunce hat.

 

I try to stay at 6 psi and under. Even still my egt's are above 600 usually 7??.

As for brakes dragging, they are all brand new, rotors pads refurbished my calipers, greased sliders. They do not drag far as I can tell.

Tires are at 50, have been sense I got the truck. I've had two alignments. Both shops say I need new parts, even the new parts are bad lol. So I'm unsure about that, it drives strait doesn't pull, even tread wear.

So I put my edge on 5, well it's hot unlocked so I dunno what that changes, and scan gauge said I got 19 driving home overhead said 23.

Some questions about timing.

How much does the edge add vs the smarty? I know on a gas Chevy 350 I can run more living at high altitude. I used to run 15 deg.

Would the same be true from a diesel? Couldn't i run more living at higher altitude then sea level. By running more j would run smarty on 3 and edge on something.

What does to much timing do to these? Same as a gasser? Will it ping or knock under heady load or high boost? I could take my turnbuckle off and dial back the edge.

Just kinda thinking out loud here.

Hot unlock probably increases your timing even more and more fuel duration. I dunno how much the smarty or edge adds and even compared to one another.

 

Timing on a gas and diesel are different as they are different fuels. I would assume the diesel would have to add more timing as well since they still require a proper air density to burn properly.

 

Too much timing is going to cause engine knock, the bad knock. The type of knock that blows motors up!

[diesel4life]

Your truck has been designed to run approx. 600* with normal driving. It sounds to me that you have a brake (or brakes) dragging. Mine at 60 mph runs at 550* and 0 to 1 psi boost. The reason you saw the EGTs drop when you went to a lower gear is because the engine was pumping more air than it was in a higher gear. My '12 VW TDI has a display that shows instant mileage and it always shows higher numbers in the highest gear it will pull in. That same concept was beaten into my head way back when I drove big trucks 30 years ago.

Which gears do you have Tom? In the case of an automatic with 3.54s, I notice any little inclines, head winds, or moderate loads in the bed can effect cruising egts. Especially below 55mph. If I get down to 50 alot of times I will kick it out of OD. It lowers the egts and the engine load. I have always disliked the 3.54 gears, I had 4.10s in my former 00, they were alot more suitable for towing but were a little low when empty. I would love to get my hands on a set of 3.73s.

[MnTom]

Which gears do you have Tom? In the case of an automatic with 3.54s, I notice any little inclines, head winds, or moderate loads in the bed can effect cruising egts. Especially below 55mph. If I get down to 50 alot of times I will kick it out of OD. It lowers the egts and the engine load. I have always disliked the 3.54 gears, I had 4.10s in my former 00, they were alot more suitable for towing but were a little low when empty. I would love to get my hands on a set of 3.73s.

I have 3:54 gears. My truck seems to do just fine with them. You will get an increase in EGTs anytime you run into a headwind, crosswind, incline,etc. because the load is increased. When the engine speed climbs in a lower gear you are pumping a lot more air hence the reduction in EGTs. The load is the same no matter what gear it is in. When I am towing my fiver my set up weighs about 17k pounds so no matter what gear I am in the load is still 17k.

[Mopar1973Man]

I have 3:54 gears. My truck seems to do just fine with them. You will get an increase in EGTs anytime you run into a headwind, crosswind, incline,etc. because the load is increased. When the engine speed climbs in a lower gear you are pumping a lot more air hence the reduction in EGTs. The load is the same no matter what gear it is in. When I am towing my fiver my set up weighs about 17k pounds so no matter what gear I am in the load is still 17k.

 

Same here.

 

 

3.55 gearing and right at about 16,000# GCW.

[diesel4life]

I have 3:54 gears. My truck seems to do just fine with them. You will get an increase in EGTs anytime you run into a headwind, crosswind, incline,etc. because the load is increased. When the engine speed climbs in a lower gear you are pumping a lot more air hence the reduction in EGTs. The load is the same no matter what gear it is in. When I am towing my fiver my set up weighs about 17k pounds so no matter what gear I am in the load is still 17k.

Your truck (which appears to be about double the torque as in factory form) may handle the load fine, but it would handle it better with a lower gear set. The engine would be more efficient running the higher rpms. (That is what I was referring to by engine load, but didnt explain myself very well). The 3.54s are ok with light to moderate loads but IMO they are just too high when coupled with a relatively stock engine and a 4 speed transmission. I think Dodge came to the same conclusion because they replaced the 3.54s with the 3.73s in the 3rd gens.

[dripley]

I hope this does not derail this from the original intent of this thread, but I have noticed a couple things which should tell me about some of what is going on...

 

1. EGT's seem to be around 700, 800 at times driving on flat road with no wind or other factors to cause excessive resistance. This is during the cold, around 20-30's. The egt temp. occurs at about 40-45mph. Going 60, EGT's are around 800 cruising.

 

2. Boost pressures at 60mph, are around 10psi with the same above external factors.

 

I'm basically getting around 4-500 miles per TANK. I know my fuel gauge is off on its reading by about 2-3 gallons consistently, and I have not factored this in when adding 2-stroke. I'm speculating that the ratio is a little high and is helping reduce mileage. I have "purged" the tank of excess oil by running an occassional tank of diesel without any 2-stroke. Does not seem to make a big difference though.

 

Seems like before, I could cruise 60 down the road with the egt's around 6-700 in OD. Taking the TDR article into account, I did some experimenting the other day and I turned OD off when cruising, it went from around 700 in EGT's to about 500 when going about 40-45. Being in 4th reducing my gear ratio, my rpms went up to that sweet spot in the engine and the load is reduced.

 

Its hard to accept this concept, as I was always taught that the less RPM's an engine has, the better the mileage... But as we see, that sweet spot is best for reducing the fuel consumption. Which now reminds me, I've got some acronyms to add, Mike!

 

Hex, I am not smart enough to know if this is your mpg problem, but your cruising at 60 with 700 to 800* egt and 10 psi of boost sounds excessive to me. I cruise around 70 to 75 at around 700* but only about 2 maybe 3 psi of boost. I dont cruise at 60 enough to enough to remember what number I get.. Just seems to me your are burning a lot fuel just to maintain cruising speed. 

[hex0rz]

Dripley, yea, it seems as though something has changed drastically and I really want to get to the bottom of it! I'd love to be able to drive along at different sets of circumstances and take a "snapshot" of the readouts and compare them with people to see what is typical.

 

As well, with what I run in my sig, I'm at about 22k lbs GCW. Which for my truck is 4-6k over rated. Although, it does good and I get about 10MPG doing it.

[MnTom]

10 mpg at 22k is not bad at all!  Towing I normally get about 14 mpg at 60 mph, 12 mpg at 65 mph and 10 mpg at 70 mph. Actually the weight isn't a big factor in mileage unless there are a bunch of hills involved. The size of the load is a lot worse (wind resistance).

[hex0rz]

When I pull my 5th wheel, I try to stay at a constant 55mph. So the other factor is the size, load, and weather. I think the lowest I saw in my MPG numbers was 8mpg. That was the first trip I made with the trailer and that involved a few big grades to get to Yakima!

 

ALSO, that is with just using my DAP injectors and Comp turned off. I've been very apprehensive to use the comp towing the trailer as I do not want to damage the tranny. I kind of figured the trans. temp guage would help me, but the other aspect of it is using too much power and snapping the input shaft or something...

Edited January 2, 2014 by hex0rz

[Killer223]

Aside from this getting off my original questions.

I live on or in a mountain town, no matter where I go there is hills involved, I drop down to get home, then have a 7 mile climb to get back to town.

Today i went on a 74 mile round trip, truck got 21 going and 16 headed home. I took my brakes apart lubed everything, rotated the tires, put edge on 5x3 as 5x5 was to aggressive, it surged with the cruise on.

Next I'm going to look for new rims as the ones i have now stick out about 1 1/2 inches or there abouts.

Running on flat ground I run 6-10 psi boost and about 700-760 egt's if down hill I'll get 3-4 psi and 560-660 egt's.

My speedo is 3% off. So I'll recalculate my mileage in a few days before my race that is 200 + miles away. I'll have only one bike in and some gear and the kids. Not gonna take the 5er this time. Gonna make the wife drive my dead *** home after the race.

I do have a smarty I'll be putting on the market. And looking for either body parts or injectors.

Thank every one of you for the awesome information you've provided.

[hex0rz]

I have to calculate my mpg numbers by multiplying the mileage of the trip by 1.08 due to my tire size.

[dripley]

Dripley, yea, it seems as though something has changed drastically and I really want to get to the bottom of it! I'd love to be able to drive along at different sets of circumstances and take a "snapshot" of the readouts and compare them with people to see what is typical.

 

As well, with what I run in my sig, I'm at about 22k lbs GCW. Which for my truck is 4-6k over rated. Although, it does good and I get about 10MPG doing it.

 

I am running at 22.5k with my trailer and get 11 mpg at 65 and less mph. I agree with Tom that your mileage is not out of line.

The egt and boost numbers you quoted earlier, were they with or without the trailer? I was assuming with out.

 

 

Killer223

It gets easy to stray sometimes and I hope you got a handle on your original problem. I remember you talking about lower fuel mileage and similar egt's like Hex. Yall both run bigger tires than I do(265 75r 16) and maybe that is the cause of it. I just dont see that kind of boost just cruising and my egt's are a little lower. Just made a trip to Baton Rouge La from Hickory NC. 800 miles  + or - and got 18.5 mpg running 70 and mostly 75. Hill country the first 200 miles and then just kept flattening out the further south  went.