Cummins 600 fuel mileage

[wyldman]

It seems as if the new Cummins 325\600 is getting very poor fuel economy.The regular 305 does much better,with only minor differences in useable power output.

What are you experiencing with yours ? What have you heard about it ? Have you or your dealer had any success in making it better ?

[Joey D]

I was reading on TDR about a TSB coming out to fix the low fuel milage and white smoke at start up on the 600's.
It looks like all the newer trucks are not recording high milage #'s the older trucks were making. GM is in the same boat with the newest D Max. Milage is down. Could be all the new emision crap.

[John DiMartino]

the "600" has a 3rd pilot injection cycle, it is this thats the cause of the mileage. That same cycle is supposed to be one of the reasons its so clean,and quieter than a gasser. I wouldnut buy one by choice anyway because its got a cat convertor on it. The 250 and 305HP HPCR are good on fuel. there are a few guys that claim there 600 gets over 17mpg.

[Crimedog]

My Ol' Man's truck is an 04.5, he started off getting as bad as 14. It is now up to 17, the last month it has been steadily climbing. I talked to a horse rancher that has 60,000 mile on his already and he gets 220-21 on average. He said his sucked until he hit the high teens (in thousands) then it took a nice jump. Dad's has I think 15,000 or close to it. One of these days he is going to let me take his cat off, see if that helps. You can just smell the unburnt fuel coming out the tailpipe:o I've been told it is also a retard in timing, so that they keep the exh. hot for the cat:( We'll see what the next 5K brings. Everytime he complains about fuel milage I ask him how many people he smoked today and that puts somewhat of a :D on his face.

[Crimedog]

Better clear this up, he is getting 17 steadily now, and that's driving fairly rough. I've also heard of the TSB coming out this October, I'm stopping in at the dealer tomorrow to see.

[Lawngodfather]

I got the 305 with 4:10 gearing...

Pulled a 10,000# load all day today started the day out with 210 miles on the tip odomotpr and ended the day needing fuel with 413 miles.

With no load I been getting 450 miles to a tank...

Same truck same gearing 4:10 with a gas 360 200 miles to a 34 gal tank was pushing it.

I now have a 30 gallons tank and put 29.04 gallons in it today

14.22 miles to a gallon.

Hyway I been gettin right at 20mpg.

City 15mpg but that is climbing some, and has a lot to do with the gas peddel on the floor.

[BWhite]

some Cummins 600 info
Prior to January 2004, the 2004 Cummins HO was rated at 305 hp and 555 lb-ft of torque. After Jan 1, the "600" was introduced at 325/600. The "600" also includes a cat-con and a revised injection sequence to cut emissions and noise.


Here's the funny part... the 2005 Cummins is now rated at 325/610 (a very quiet notice was sent to dealers about this). Why the tiumy bump in torque? To stay ahead of the 05 Duramax which is also over the 600 lb-ft mark (but only with the Allison automatic).

[John DiMartino]

the numbers game wil continue,as far as torque goes, i dont think Ford or Gm can match the torque that a Cummins can make,so ultimately the trans will limit the Cummins.I think the ford ,GMs torque numbers will keep coming at higher RPMS if they want to match the numbers made by Dodge.

[wyldman]

Yes,the trans and drivetrain capabilties are the limiting factor for torque output.

The Cummins will always be ahead torque wise,as an inline engine is a much better design for making good torque.

[Lawngodfather]

19.8 mpg all hiway for a trip to KY

[synner]

I sure hope the mpg increases with mileage because right now my 2005 CTD is as bad as my 94 F250 with a 351 gasser and a C6 tranny. Only 6500 kms on the clock right now, we'll see how it goes.

[BWhite]

Seems like you just have to break them in . Did the previous versions experience lower mileage when they were new ? I would think they would have ?