I like it, but getting very frusterated

[tireguy]

Well i dont know where to start-----
I have a low mileage creme puff of a truck with as follows...
Heath diesel (HD)
IP
cooling system
high flow in.
High per. ecm
turbo master
3inch dp with 4 inch exhaust before i bought it. i think SS diesel
f code intake
ful set gauges
Now for all my problems, my mileage empty 65 mph is around 17.5. i just got home from pulling my camper 150 miles. we are mostly flat a few small hills that last at most a half mil. combination wieght is around 12,500 lb. i made 7.5 mpg ya it just sucks it down!!! it also seems crazy that with my setup i cant get high egts, flat on the floor up hill it barely hits 1000 thats measured pre-turbo. and i dont have prievious experince with these engines but those small hills or a 20 mph cross wind puts me in 3rd around 12 psi boost. it just acts like thats all it has. im running the stock air filter assembly without the snorkle so that maby hurts me but i dont think that bad.
I feel like i have tried to curb this engines weaknesses but its not returning much for the money ive spent in the last 6 months. any help please.:nonod:

 

[JMJNet]

For a 1500 truck pulling 12500 lbs, IMO, is very good.

What is the gear ratio in the truck?? Too low won't pull nothing, too high bad mpg.

 

[tireguy]

whats a 1500 have to do with it the f code motors in 2500 and 3500 do have a few more # ft. of torque but its very close to the same. Bill Heath says these trucks when in good condition can not burn more fuel tha what would equate to 11 mpg. he says u shouldnt get less than that even at wot for the whole tank. Do the members of this forum feel the same or is that unrealistic???
The gear ratio is 3.73

 

[WarWagon]

whats a 1500 have to do with it the f code motors in 2500 and 3500 do have a few more # ft. of torque but its very close to the same. Bill Heath says these trucks when in good condition can not burn more fuel tha what would equate to 11 mpg. he says u shouldnt get less than that even at wot for the whole tank. Do the members of this forum feel the same or is that unrealistic???
The gear ratio is 3.73

:skep: Bill must be rolling the salt flats too much and quite frankly has an unimpressive "test hill" he uses. :rof:

10% grades that go for miles on our pull to Payson gets me down to 7.5 MPG and that is with a 4.10 rear. After I turned my fuel and boost up I went from 34 MPH to 43 MPH. MPG was the same. However the harder you load an IDI engine the worse the MPG gets vs. other designs. Rebuilt or worn out engine is the SAME MPG!!! 2 trucks, 3 engines all the same. The weight in the trailer would change my MPG. (A 2007 Dodge 4.7L gas engine pickup as well as a 6.0L V8 Trailblazer SS were in the 6 MPG area same route till the trans on the Trailblazer SS let go... But were holding the speed limit on the hills.)

Recall you have an economy engine that will not compete with the power the other diesels offered. Loaded this engine looses the MPG battle as well. No one else offered a diesel in a 1/2 pickup.

 

[tireguy]

so are u saying you would feel im seeing something very typical?

 

[buddy]

17.5mpg, not so untypical, 7.5mpg towing is low, should be more like 11-14mpg when towing.

What kind of fuel are you using?

And you just updated the timing, are these number before or after that?

That stock air box is crap. What is the thermostat in it, what temp does it run while driving or pulling? What is your boost while cruising empty or cruising flat land towing?

It shouldnt be that jumpy to go into 3rd gear, thats a program thing, and it also depends on the speed, if youre going 50mph at 1700rpm and hit a hill it will downshift, but if your going 65mph at 2200rpm, it wont downshift so eaily. A performance PCM may be programmed to downshift quickly.

 

[tireguy]

17.5mpg, not so untypical, 7.5mpg towing is low, should be more like 11-14mpg when towing.

What kind of fuel are you using?

And you just updated the timing, are these number before or after that?

That stock air box is crap. What is the thermostat in it, what temp does it run while driving or pulling? What is your boost while cruising empty or cruising flat land towing?

It shouldnt be that jumpy to go into 3rd gear, thats a program thing, and it also depends on the speed, if youre going 50mph at 1700rpm and hit a hill it will downshift, but if your going 65mph at 2200rpm, it wont downshift so eaily. A performance PCM may be programmed to downshift quickly.

these #s are with good timing (-1.94) 195 degree ther. temps are 195 to 218 ( slowed down) i think my rad is toast or buggy.
Boost is 4 to 6 empty and 6 to 11 towing. it shifts most of the time at 11 psi into 3rd then ranges from 11 to 14 against tm.
Rpm at 65 in od is 2100

 

[buddy]

You probably have some tall tires on there, what size are they, and tread type?

Are you sure the odometer is correct? how about the speedometer?

Is this using Bio blends with lower BTUs in them, or #1 or #2 ULSD. Any fuel additives?

 

[tireguy]

I have 265.70.17 tires which is 1.2 in. taller OD than stock they are not a highway tire but not a mud tire by any means.
My odo. is off 1.3 percent (checked with gps and timing through a mile)
no bio blends that i know of, and i think it would be #2 diesel
I run a pint of 2 cycle oil at each fillup

T think it about has to be in computer programing, but bill has looked over it and nothing catches his eye. I come to this because most of the other major components have been replaced.

It drives smooth, starts fine, just likes the pump to much.
It makes me think there is something wrong though that i cant get high egts, its not that i want them but with my setup bill says i should be able to push 1300 degrees, he dosnt think my probe is reading right. its a new bully dog setup, probably doesnt mean anything but its hard for me to suspect it right away

 

[buddy]

Poor mileage under load I would think could be a couple things.

Normally, I would think injectors. Poor atomization under load makes things worse. Also if you recently put the injectors in maybe you have a fuel leak that gets worse when pushing higher fuel rates constantly under load. Higher fuel rates pushes injection pressure up several thousand psi. Since it seems the injectors are recent I would look for leaks.

Another thing could be too much injection timing advance, because it may be burning too much of the fuel before TDC which is working against you. Too late of injection and you dont have much power at peak torque angles, but smooth operation. I suspect that an intercooler or WMI would yield a good amount of efficiency gain because it would cause delayed ignition and more fuel burns at TDC and shortly after. A little less advance in the sustained fuel rates while towing would probably help.

You can also try a bit shorter, thinner tire, would probably help. Like a 235/75/17, or 245/70/17

 

[tireguy]

do u have an idea on low egts?
by the way i was taking an educated guess on fuel mileage and now i filled it up for a real check and it went 8.4

 

[buddy]

My EGTs never get that high either, it could be my gauge, but hardly ever see 1000F, and I push as much fuel as anyone could. Its not ever really hot where I am with a good bit of humidity, not exactly your case. If you stayed locked up in OD and just maintained 2100rpm rather than downshifting, I bet EGTs would go up a little more. I think some EGT gauges are not as sensitive as others and some are more sensitive than they need to be.

It sounds like you have the right amount of boost, or a little more than you need. If driving empty at 2100rpm cruising, try loosening the spring so you only get 3psi of boost, it will likely get better MPG.

 

[tireguy]

ill have to try that.
Thanks for your help thus far. im going to try talking with bill H. in the mouning see if he has any more ideas