Question: RPM range for best MPG

[werewolf]

Just wondering if any of you have ran across a specific RPM that get the best MPG while towing. I have the EGR deleted and have tried towing with PPE on level 2 and really not impressed with my MPGs, only getting around 9. Mostly highway speeds at about 70 MPH and around 1750 RPM is my numbers from my last haul with a 7000-7500lb boat.

Is this normal?

Just wanted to see what any of you thought

 

[hondarider552]

When I had my PPE I got the best MPG on level 4.

 

[LWATSON]

I got good mileage on level 4 but I got my best on level 3. Level 2 wasnt good at all for me.

 

[werewolf]

Was that while towing though or just driving around?

 

[Lofti7]

while towing my 21ft boat from 1600-1700 rpm keeps me at 65-70 seems to be the sweet spot for me about 15mpg my boat is a little lighter probably 5500ish @ 75 i get around 12-13 mpg and at 80+ I get around 9-10 mpg.

 

[LWATSON]

Was that while towing though or just driving around?

It's been a while but I think I got my best mileage towing and driving empty on level 3. Just be easy on level 3 when your towing, you do have guages right?

 

[werewolf]

It's been a while but I think I got my best mileage towing and driving empty on level 3. Just be easy on level 3 when your towing, you do have guages right?

Not at the moment. Thats the next step in the process and why i am taking it easy on the truck.

 

[1953drtelco]

I drive around 62-65 mph towing my boat....boat/trailer around 6500 lbs. I have a tow tune (EFI) 7500 lbs or less and get around 14 mpg....I drive light footed when towing, with most of the time on cruise control.

 

[nuffsaid]

Try towing in manual mode and select 5th gear. Truck has power to pull in 6th, but it makes the engine work harder, higher egt's and more boost.

 

[LWATSON]

Not at the moment. Thats the next step in the process and why i am taking it easy on the truck.

Get guages as soon as you can. I've never had trouble towing on flat ground but hit a little grade and EGT's climb fast. As mentioned before tow in 5th gear and that will help with EGT's, I think I actally get better mileage towing in 5th instead of 6th.

 

[A_T_Ver]

I know anything after 2000rpm, and fuel mileage drops quickly.

 

[werewolf]

Thanks for the replies. It seems I gotten more feefback about dropping back to 65, just been running 70 since that is the speed limit, but with a load it would be better to have more miles out of it than get there a few minutes quicker. Also, the manual mode 5th gear has been suggested, things I really hadn't thought of. Just thought the tow/haul was all i needed to use. Will try these out and hope that gets me a least breaking double digits.

Thanks again

 

[duramaxdiesel]

I know anything after 2000rpm, and fuel mileage drops quickly.

That is exactly what I see too.

Nick

 

[TonOfDalt]

Thanks for the replies. It seems I gotten more feefback about dropping back to 65, just been running 70 since that is the speed limit, but with a load it would be better to have more miles out of it than get there a few minutes quicker. Also, the manual mode 5th gear has been suggested, things I really hadn't thought of. Just thought the tow/haul was all i needed to use. Will try these out and hope that gets me a least breaking double digits.

Thanks again

From what I know the "Tow/Haul" mode simply changes the shift characteristics for the transmission in the TCM. It may change fueling slightly to help with EGT's but I think it just changes the shifting feel as I have never seen anything about the "Tow Haul" mode in EFI Live while programming and the manuals dont have this feature.
I believe the mileage increase you will see from towing in 5th instead of 6th isnt from dropping to 65 from 70 but mainly due to your pedal position. These DMAX motors seem happiest at 1800 RPM and throttle position below 50%. They are very sensitive to throttle position... This is why many see the best mileage with a hot tune, because in a hot tune you will see the most timing "cylinder pressure" in the cruise area and therfore see the most efficiency.

 

[DBUSHLB7]

I just towed our boat (5-6k) from ABQ to Page AZ(Lake Powell) and back. Used the lowest tune on my DSP5 and set cruise at 75. Elevations went from 5k to over 7k in Flagstaff and one 6%grade just before Page. I got 13mpg. Wanted to use the stronger tunes in DSP but didn't want the boat cover to get covered in soot. Best MPGs I ever got was driving on flat west TX roads with cruise set at 65-70. Got 21

 

[wildwolfproducts]

My truck is stock and towing our 16,000 lb 5th wheel I get 10 MPG running 70 @ 1900 RPM's

 

[duranut03]

I am stock except for the tires and pulling a 9k lb camper I never get over 9.5. I honestly don't se much difference between 65 and 70. I get basically the same fuel mileage. I have tried trips where I played every card trying to get better mileage. Nothing makes any difference for me.

 

[Boostlee93]

As others said i see a major drop after 2k with my best mileage right around 1800rpms or so which puts me at about 65-68mph.

I got about 14mpg towing 12k from florida on my 100hp DD tune until the tranny took a shit..lol Dropped it down to the tow tune and it hasnt shifted the same since. Time for a tranny build i guess. :woott:

 

[Doug Diesel]

Mpg

I tow a 15K 5th wheel with my PPE on 3 and I leave my truck in 5th gear and travel around 65 to 68 and I get 13.5 on flat ground. If I go to 6th gear it drops the RPMs to around 1500 and my fuel mileage goes down to around 12.

 

[adeso]

Don't forget to factor in wind, up at 60-70 mph a 15 mph head or tailwind will factor a lot. IIRC 1800 rpm is around where the peak tq is on the stock engine. I still think mph/wind is the biggest factor towing something like a camper