How to improve MPG....

There's a reason why the mega carriers govern their trucks at 60 mph to 65 mph, for fuel economy. Safety comes into it as there are so many new drivers, but fuel economy is the key.

I'd recommend the OP set cruise control at 62 mph. It will likely result in rpm's in top gear running at around 1200-1300, which is the "sweet spot" halfway between peak torque and peak horsepower. Run at that speed for a couple fill ups, as long as you can make your deliveries on time, and I think you will find a huge increase in fuel economy.

Running an ungoverned truck at 62 mph is a very good thing. Whenever you start creeping up on a 62 mph governed mega carrier truck you can easily increase speed to make a safe pass and let it come on back down to your cruise control speed.

Depending on your engine and idle rpm's you can be using anywhere from 0.4 gal to 1.0 gal per hour. Idle as little as possible.

Accelerating doesn't have to be at maximum throttle from a standing start. Be easy on the throttle and you'll find some savings. Use progressive shifting and take your time getting up to speed unless you absolutely need that speed, like when needing to get up to freeway speed to merge safely.

The bottom line is you want to keep from flooring it habitually. Be easy on the throttle 99% of the time. Come to think of it you should also be easy on the brakes as well. Don't be roaring on up to a stop and then standing on the brakes. Coast into your stops whenever possible.

 

try to coast in neutral as far as you can on all downhills..

 

http://www.rawze.com great stuff on how to maintain your Cummins ISX.
I have a Detroit and I still monitor that site for ideas on maintaining my emission systems.
You probably have a sensor clogged up with soot. Although 75 mph is a big factor too.

 

I just bumped up my cat c-15 acert form 435 to 550/1850. made no difference in mpg, still only 5.2/5.5 .
13 speed 11r 22.5's 355 rears. going to look in free flow mufflers see if I can get in low six's.
I'd be happy with that. run about 64/65 turning just under 1400 rpm.

 

Run 62-65 but DON'T run the cruise, you know when you're about to top a hill and can roll out of the throttle and let it roll over the top, then gradually pick you speed back up, the cruise only sees that it's not doing the proper speed and runs WOT till it gets there, that's wasted fuel.

Again, slowing down helps, it's like a 10% drop in fuel mileage from 555 to 65, but like another 8% from 65 to 70, then another 7-8% to 75 mph. Also, look at putting some high flow mufflers on it, they can help .2-.5 mpg.

 

I agree that if you know how to drive efficiently you can get better fuel mileage by "free footing" than using cruise control in rolling terrain. Cruise can do better in the flats. Get an mpg display of some kind, or a boost gauge. Keep boost at or below 50% on your climbs unless you have to bite the bullet and floor it to climb a long sustained grade.

 

here you are, shows clear why you get 4mph;


Increasing speed from 55 to 75 mph can increase fuel consumption by over 50 per-cent, while cutting tire fuel efficiency by nearly half.

more here; http://www.trucktires.com/bridgestone/us_eng/brochures/catalogs/fuelecon/2.asp








http://www.atdynamics.com/


[video]http://player.vimeo.com/video/101716154?theme=none&wmode=opaque[/video]

 

mufflers won't do it. Tried that. What does work is around $10,000

 

Yep. Gotta decert that acert.

 

how many hours of idle time do you have
more fuel goes up the stack with the brake pulled then any other
along with speed over 65
speed racer around parking lot and on ramps