So on our trip, really bad milage dmax

[Cili]

Definitely check the basics first, but injector health is everything in a duramax. With 120k on them I would be prepared to put some in sooner than later.

Even if the truck isn't hazing, or smoking, or putting fuel in the oil, the injectors could still be returning too much fuel and robbing you of power.

 

[ktmoutfront]

I thought you can buy a programmer and get 1k mpg and 4k hp. Easy fix.

 

[blazinzuk]

I thought you can buy a programmer and get 1k mpg and 4k hp. Easy fix.

That's my plan so I can get 40 mpg too!!

 

[miniwally]

That's my plan so I can get 40 mpg too!!

An LB7 Dmax with 120,000 on injectors is about 20,000 to 40,000 miles past needing injectors, at least that's my opinion

It's probably got bad injectors and isn't burning all the fuel due to bad spray patterns and dripping fuel on the edges of the window that the injectors are firing.

 

[ChrisPerry]

Eric, check the driver side intercooler tube to see if it has rubbed a hole in it on the power steering line right above the steering box. Had that issue when I got my 02, was costing me a little power and fuel economy.

At 55 towing mine gets ~14ish and at 75 towing it gets 10. A progammer helped fuel economy by 2mpg and added lots of power, last run to BB running 75 I got 11.5-12.

 

[max 02]

Eric, check the driver side intercooler tube to see if it has rubbed a hole in it on the power steering line right above the steering box. Had that issue when I got my 02, was costing me a little power and fuel economy.

At 55 towing mine gets ~14ish and at 75 towing it gets 10. A progammer helped fuel economy by 2mpg and added lots of power, last run to BB running 75 I got 11.5-12.

THIS!! Intercooler tube!

That was going to be my suggestion on the problem. And fuel and air filter for sure...cheepish and easy.

We replaced the injectors in our 02 last fall cause it was smoking white...still had lots of power though.

 

[ClassicStyle]

I typically ran 12 or so with my lb7, 17-19 unloaded. My lmm is another story...

Check charge tube, and is it really clacky? Pass rear two cylinders are typically first to plug, injector knock is noisey, sounds like a clacky old deisel under load. If those cylinders are running lean because the injectors are plugged up, it will de fuel that side trying to balance. Explains down on power, if your having to get into more to keep going explains mpg.

Last set I did had 80k miles, light light haze, but noticeable injector knock.

 

[sweetk30]

I typically ran 12 or so with my lb7, 17-19 unloaded. My lmm is another story...

Check charge tube, and is it really clacky? Pass rear two cylinders are typically first to plug, injector knock is noisey, sounds like a clacky old deisel under load. If those cylinders are running lean because the injectors are plugged up, it will de fuel that side trying to balance. Explains down on power, if your having to get into more to keep going explains mpg.

Last set I did had 80k miles, light light haze, but noticeable injector knock.

wow that's what about 1/2 of my buddys looked like on his . and he found the rust pitting at that seat area on the lines like I said above .

he did it all in my shop with basic tools so its just a lot of labor to do them . he even adjusted the valves since he was in that far .

did the cat fuel filter adaptor unit also . got it from a ebay sale even with cat filter new on it.

 

[ClassicStyle]

They they're not hard, I bought snap on's injector puller and have never had a cup pull.

The job takes a good picture and looks over whelming. But they're easy, just time consuming. I'd rather injectors then the cp3. Hah

I deleted my filter and just ran a air dog 165.

 

[sweetk30]

buddy used a old injector line to wiggle and pull out since there was new set on the way . no puller for him or cup pull out.

and yes LOTS of pictures to aid in reinstall help for sure . he was glad he did .

 

[blazinzuk]

I told my MIL in law she was gonna need injectors soon and to start saving.

I'm pretty sure my in laws belief system when it has to do with cars is ignorance is bliss.

She swears up and down that her truck has gotten 15 mpg pulling this trailer all the time.

Gonna replace the fuel filter and air filter day after next. We get to my SIL house and will be there with nothing to do for a day.

Gotta fix 3 windows in the fifth wheel and try to figure out the black water tank. As its having issues.

Couple of noises and vibrations to see if I can chase down on the truck too.

I swear everyone who has used this thing until us, basically Kristles brothers, has just ignored every problem. I just can't do that.

My MIL has ZERO idea how anything works at all. Blows my mind how little she knows about this trailer.

Ignorance is bliss

 

[ChrisPerry]

Do you have any way to read commanded vs actual fuel pressure? I know when I replaced my cp3 earlier this month, both power and economy increased. Old pump couldn't hold rail pressure in 4th or 5th gear.
Only drawback to fixing it was that I completely killed my trans in 3 week's. lol

 

[FOR MUD]

Still waiting for a Cummins story about 45mpg towing a Cat D10 over the rockys doing 110 mph. Other than that, not much to offer. The worst part is you have a lot of time to think about as you drive along.

 

[ktmoutfront]

Still waiting for a Cummins story about 45mpg towing a Cat D10 over the rockys doing 110 mph.

I was thinking the same thing.

 

[blazinzuk]

Do you have any way to read commanded vs actual fuel pressure?

I don't Chris.

Don't really have much in the way of tools with me. Brought a basic wrench set and sockets. Some screw drivers and pliers.

Gonna replace the air filter and fuel filter today. See how that does

 

[ChrisPerry]

I don't Chris.

Don't really have much in the way of tools with me. Brought a basic wrench set and sockets. Some screw drivers and pliers.

Gonna replace the air filter and fuel filter today. See how that does

Ok, don't forget to clean the maf sensor while your at it. That always helps a bit.

 

[blazinzuk]

I replaced the fuel filter and the air filter. I have only driven a short period with it. Less than a mile. It feels way more powerful. Moves out way better.

250 miles tomorrow and another 200 the next day so should have a good read on milage numbers

 

[ChrisPerry]

I replaced the fuel filter and the air filter. I have only driven a short period with it. Less than a mile. It feels way more powerful. Moves out way better.
Cool
250 miles tomorrow and another 200 the next day so should have a good read on milage numbers

 

[76zimmer]

Eric, If you still plan on getting to my place let me know and maybe we can work on it some at my place? I ain't much help on a Dmax, but we could look at my pretty Cummins and wish good will on the Dmax!

 

[blazinzuk]

Eric, If you still plan on getting to my place let me know and maybe we can work on it some at my place? I ain't much help on a Dmax, but we could look at my pretty Cummins and wish good will on the Dmax!

I do still plan on dropping by Dave but it sure isn't to work on this thing!