2 questions

[farmer70]

Is there a way to search past posts? I’m sure my main question has been covered before. Realistically what kind of MPG can I expect out of a Peterbilt 389 flat top pulling a hopper weighing 80,000 everywhere? It’s got an ISX 500 13 speed and 3.25 rears. I was in the wind yesterday and my mileage was horrible. I’ve got a lot of bad habits I know. I’d be ok with 5.5-6 how difficult is this. I had a daycab Freightliner with a C12 cat and a big gap between the trailer and cab. I think my mileage was better. Will the EGR tune up help a bunch? I pulled the imap sensor it had a little buildup. The engine is a 16 2350. Will change the Delta sensor. On flat ground which I’m on a lot it seems like if I set the cruise at 62 in 12th gear I’m at 1400 RPM seems like a good setting. What is recommended? I know my aerodynamics are crap but what’s attainable realistically?

[Mattman]

Cruise control is hard on fuel mileage. Your foot and letting the truck slow down when pulling a hill versus cruise control commanding full throttle to maintain set speed would help a little.

I believe EGR tune up has more benefits than fuel mileage. Could help your truck run well and keep it out of the shop potentially.

[farmer70]

This not using the cruise control is new to me. I’ve always heard use the cruise and let your engine pull the hills by letting it pull down like to 1200. Im like a drug addict I’m trying to wean off my bad fuel wasting habits.

[tree98]

Keep it 1500 rpm or above no matter what if your pulling a hill !! That means downshifting, sometimes a lot by the time you get to the top. I'm not a hypermiler like a lot of guys on here but I am concerned with keeping my liners pinned down where they should be.

[farmer70]

That’s good info thanks

[Mattman]

Engine being lugged down to 1200rpm is going to be working harder than one spinning at 1500rpm and not lugging. Your truck should have a fuel mileage graph in the dash. It may not be the most accurate but watching it will show when you are getting the lowest mpgs.

Liner issues due to low rpms and high engine load seems to be a problem for these engines. Most recommend at least 1300 to 1400 rpm or more with say over 30 to 40 percent engine load

[farmer70]

With the truck set up as I described What gear RPM and speed should I try to obtain the best mileage and safe on the engine? I’m used to Cats and my C12 will out pull this ISX. I’m trying to learn and appreciate all advice. Specifically 12th gear 11th gear? 12th an 1500 would probably put me about 66.

[tree98]

I only use cruise on flat ground to give my foot a break.

[farmer70]

{removed =-- BAD INFORMATION!}
Found this on search for proper driving techniques for a Cummins ISX. I’m not arguing with you guys I’m just find it interesting

See this is why I’m confused