I’m new here and I have some questions.

[cowboycurtis]

(01-14-2020 )Waterloo Wrote:  As far as your fuel mileage, that is going to be up to the driver, first thing you do is slow down, best fuel economy is going to be around that 60 to 63 mph at 1700 or so rpm's. I have an 18 speed in my truck and run her on the highway between high 7 and low 8. I rarely go to high 8.

Wow. That surprises me. Mine is also an 18 speed and just assumed that lower rpms were better if the engine wasn’t completely bogged down. I figured if it could gain speed from around 1400 that would be a good spot to let er run. Crazy thing is I can get 7-7.5 mpg in those Detroit’s no matter how hard I push em.

Fuel is expensive but so is time. I’ll sacrifice a little fuel to save some time. Trucking is a secondary job to my farming and seed operations.

[Waterloo]

(01-14-2020 )cowboycurtis Wrote:  

(01-14-2020 )Waterloo Wrote:  That is a good sign! You need to see what is on the ECM, if you can pull the actual file and get it to one of the guys here that would be the first step to figuring this out.

Ok. This is exactly why I started this thread! I’m a rookie at this stuff, especially ECM stuff, so point me in the right direction to get the ball rolling. Thanks for all the help, greatly appreciated!

First thing, you need an Inline 5 or 6 reader with the software. Most all of us here use eBay, the Chinese or Hong Kong outfits sell the complete package for around $250 to $300, you supply the laptop, Windows 7 is the best OS to use, but with some tinkering, it will work on Windows 10.

Pull the file, and send it to Rawze, Unilever or Mommaburt. Rawze can read it and tell you what is amiss, Unilever is the 870 guru here, as far as tuning along with Mommaburt. Extract that file and get it to one of these guys.

Maybe your mechanic can do this, but if you are going to keep that truck you are honestly going to need the reader and software. These shops and dealers will just misdiagnose and empty your wallet. Time to be proactive and put the mechanic hat on, most all of us here learned this truth the hard way. It cost me $38,000, I quickly learned how to in frame an ISX, and that is exactly what I did.

[Waterloo]

(01-14-2020 )cowboycurtis Wrote:  

(01-14-2020 )Waterloo Wrote:  As far as your fuel mileage, that is going to be up to the driver, first thing you do is slow down, best fuel economy is going to be around that 60 to 63 mph at 1700 or so rpm's. I have an 18 speed in my truck and run her on the highway between high 7 and low 8. I rarely go to high 8.

Wow. That surprises me. Mine is also an 18 speed and just assumed that lower rpms were better if the engine wasn’t completely bogged down. I figured if it could gain speed from around 1400 that would be a good spot to let er run. Crazy thing is I can get 7-7.5 mpg in those Detroit’s no matter how hard I push em.

Fuel is expensive but so is time. I’ll sacrifice a little fuel to save some time. Trucking is a secondary job to my farming and seed operations.

NO NO NO! If you run these ISX motors at those rpm's you will bust a liner lose! Usually the #5, it is a design flaw from Cummins. These motors need to be kept above 1400 rpm, I try to keep mine above 1500 rpm's. I run her right up to 1800 or 1900 to complete the shifts, you will not hurt the motor running that high.

What gearing do you have in that truck?

[cowboycurtis]

(01-14-2020 )Waterloo Wrote:  NO NO NO! If you run these ISX motors at those rpm's you will bust a liner lose! Usually the #5, it is a design flaw from Cummins. These motors need to be kept above 1400 rpm, I try to keep mine above 1500 rpm's. I run her right up to 1800 or 1900 to complete the shifts, you will not hurt the motor running that high.

What gearing do you have in that truck?

Not sure on gears. It runs 1500 at 70 mph with 11r 22.5.

Could you post a link to a reader that you’re talking about? I’m planning on keeping the truck for a while and I have an old computer on windows 7.

Again, thanks for the help!

[cowboycurtis]

Is this what I need?

https://www.ebay.com/itm/Cummins-INLINE-...SwIJlZ9U~7

[Lonestar10]

Yes it is

[Waterloo]

(01-14-2020 )cowboycurtis Wrote:  Is this what I need?

https://www.ebay.com/itm/Cummins-INLINE-...SwIJlZ9U~7

That is it! And it sounds like you are running around a 3:34 or somewhere around there. At least you have an 18 speed, you can split the gears and get her set like I do. Or swap the gears out, that is what I would do, go with some 3:55 or somewhere around there.

[cowboycurtis]

Ok. Got one coming. Takes up to a month to get?? That’s ridiculous. Almost bought one on amazon for a $100 more and get it in 2 days.

[cowboycurtis]

I’ll mess with the engine rpm next few loads and try to keep it around 1500 no matter the speed and report back on my mpg. My manifold pressure will still be low though.