Low mpg, little help

[Diesel Warrior]

I did some seaches and came up empty. I'm new but have been lurking for quite a while. My buddy has a '99 7.3 Dually CC w/Alum dump body, 4.10s 4x4, regular maintenance up to date. The best mileage he's ever got since 02 is 11.3mpg when he still had the regular bed on it. Since then he's added the dump body and also a Motorvator chip from Summit Racing. Post chip he says he gained some low end and the shifts are better but his mileage still stinks, 7-8 mpg, less when towing or loaded big. He describes the exhaust as burning your eyes when near the back of the truck. Is there anything wrong with his PSD, and if so what are some things he and I can check?

Thanks in advance,
This is a cool site.

 

[NJKen]

My milage has not been too good either but his is terrible. We have one in our fleet that towes 15K every day and it gets beter milage than that. Some truck seem to get beter than others but I feel his is low.
Good Luck in you're quest and welcome to oilburners
Ken

 

[69oiler]

i'm getting 13 right now. i wonder if it's winter fuel, or if ULSD affects milage. i'd like to see the 16-18 mpg some guys get.

 

[geonc]

Well for starters, ULSD-----SUX

I know I loose a couple MPG even with adding Diesel Kleen additive ....and that just wastes any effects of the so-called lower fuel price

I would suggest loosing that particular chip and giving Jody Tipton or twildman a call to get some real tunes

http://www.dp-tuner.com/

 

[GSF35099]

I have been getting decent MPG with my Hypertech chip. 16 to 18 when not pulling..

I agree with geonc that the chip should be changed and try one of the others he recommends..

Good luck..

 

[Mike]

Wowsers, to be @ 7-8 mpg I think we have more than a tuning or chip problem here.

• This has been going on since 2002?
• How much does the truck weigh?
• What is his normal payload?
• What has the maint sched been like on the truck?
• How many miles on the truck?
• What is his driving style like? ie; leadfoot?

Welcome to OB!!

 

[Diesel Warrior]

Thanks, nice to be here. He has just under 110k on it, it's a Crew Cab dually w/4.10s and maintenance has been sufficient (I'm new to diesels, not trucks). He has had upwards of 5 tons of payload, and has an 8 ton dump trailer in which he hauls his mini-excavator, skidder etc, as well as gravel dirt etc. He's not afraid of the throttle, but this is no racer. The sequence of events is kinda like this:

Buy's it used in 02 with regular dually bed, Best mileage EVER (empty): 11mpg
Replaces stock bed with Alum Dump body, best mileage (empty): 8.2mpg
Adds Motorvator chip from Summit Racing, gets better shifts and can now "smoke tires" off of the bottom, but he was very disappointed in the above 1100 rpm range, little gain. Mileage improvement: none.
Transmission rebuild at ~98k miles, heavy duty sprags, servos etc. Still shifts better with chip.
When he loads up and/or tows his mpg is abysmal: 4-5mpg.
Question I'm looking to ask is this: Is there something wrong, injectors, pump, clogged cat? This is where I have no experience. Can I check injectors or is this something a shop has to do? I can wrench I just don't know where to start. I find it hard to believe that a different chip will get us 5-6 mpg worth of gains, where I am hoping we should be! I would think the stock tune should still be able to break 10 mpg empty.

 

[Tinman875]

I borrowed my buddies 99 long box, 4x4, 1 ton went from id to ky with a 20ft trailer and picked up a 01 dodge cummins that was broke down. with the trailer empty it avgd 17 and loaded 11. It had the edge box, and i used stage 2. I weighed it at a public scale in Iowa and feuled up with the load ( on way home) it weighed in at 21,350. I was very impressed. I could set the cruise and not touch it. Hate to say that i actually owned the dodge, and yes it did leave me stranded. I fixed it up and traded it in on a 02 f250 stroker with 13k on it. It now has a 4in turbo back, and intake. Made 17 loaded with atvs on a trip to the coast last summer.

I think i would check the injectors in it, basically start with the feul system. good luck. TM

 

[Cowboy2199]

I would tell him that to "chip" it doesnt do much in itself, just changes the shift points and how much fuel it injects. He should change out to an open breather system like K&N, and possibly change out to an ATVS turbo. Basically if you do a small upgrade others are required to fully appreciate the initial upgrade.

 

[94f450sd]

take it to a shop that has a scanner or the dealer and have a contribution test done it as well as a buzz test.it may be time fr injectors or injector Orings.

 

[Muddinkev44]

are you positive he can multiply correct.....

 

[blowinblack]

ULSD sucks, cost me 2-3 MPG

 

[Agnem]

I've noticed that how you drive has a lot to do with it. With a stock program, it's real important to get above that 35 or 45 MPH where the torque converter locks up. For instance, if your in a 30 MPH zone, and you just accelerate to 30 MPH, your converter will never lock up, where as if you get to 35, and then back down after it locks up, you'll use a lot less fuel throught that slow zone, and don't drop below 30!! Exhaust that burns the eyes though sounds like there is more unburned fuel in your exhaust than in mine, and I'm one of the lucky ones getting 18-20 out of an 8000lb Excursion on a stock engine with a K&N filter.

 

[Tinman875]

Agnem, i have to agree with you. Being trained in a big truck (pete) and going on the road actually made me a better driver in my own truck. Habbits really play a key on mileage. Its funny but i do the exact thing in my 02, except only getting 17mpg. It's funny to ride with someone who feels they have to floor it every time they start from a stop, or go from one speed zone up to another. If you roll gently into the throttle and actually let the gear work and the engine pull, you do save fuel. Sure you not going to get to the desired speed as fast, but you are saving feul. Not saying it isn't fun to slap it to the floor and blow some smoke, but the way prices are I can't afford to do it all the time in day to day driving. Still lovely technology lets us drive these 8500lb+ trucks and get good mileage--when i remember having my old 78 ford with a 429 in it and if i hit 10mpg i was all excited

 

[JLDickmon]

for what he's doing, and how he's driving it, the fuel economy is acceptable.

if it burns your eyes to be near the back of the truck, raw fuel is being wasted and dumped down the tailpipe.

throw that stoopid chip in the trash,

get a set of gauges

open up the intake & exhaust

switch to bio if you can find it (to replace lubricity)

add a cetane booster to the fuel

and #1: realize that a diesel isn't ever gonna snap your neck like a gas motor, so quit trying to haze the tires while towing 5,000 lbs of excavator.

I could tell from your first post that your buddy's problem is is driving habits.