When to use Tow/Haul mode?

[rock04max]

Originally Posted by loubazooka

Ditto that, why would you guys want to haul without it ? just asking ...I use it ALL the time when trailer is hooked up

likewise no matter what i hook up i use the t/h. I take of overdrive when im towing 16k or more.

[Ranger Ric]

I manage a State in Washington State and talk to alot of rv haulers, one of my camphosts has an 01 3500/allison set pulling a 16k moblie suite fifth wheel and got 10 mpg. I haul a 17foot toyhauler and with the Harleys and loaded for a trip it goes about 9k and I get 10 mpg. Has anyone else found the to be true or consistent. We do haul up here in the inland North West with many mountain passes, but once we are out of there it flattens out on ur trips even in AZ lately I got the 10 mpg. Yes I concur the T/H is a great invention, I use it running empty over passes in the snow and ice for downhill braking.

[Ranger Ric]

Sorry,
I manage a State park not the entire State, wouldnt want that job.

[rock04max]

Turbo's have a/r (air ratio) induction wheel measurements. The induction wheel puuls a certain amount of air then flattens out. If you go above the flat spot you will only burn more fuel because, the turbo can only pull a certain amount of p.s.i. Without going into lengthy dissc. you can put in perspective.

[lubeman1969]

I used the t/h mode this past weekend for the first time and willl agree it was great for braking and keeping the trans temp down. I was pulling about 5k through some very steep hills and passes in Murphy NC, got 10 mpg. I think some times it felt like it didn't want to downshift very easy, maybe it was "fighting " with my Edge controller?? The engine has no lack of power whatsoever, but maybe it would help to use the manual shift feature more often?

[daddysLBZ]

Cruise brakink not active in manual mode,I use it and never manual shift higher than about 2700 rpm's,seems to work well though..

[daddysLBZ]

Like the way the T/H works,positive lockup of tourque con. Use it a lot when not towing to ease to a stop,or punish her a bit i.e. SMOKING PSD's OR CTD's,love the LBZ with allison!!!

[Ranger Ric]

Originally Posted by rock04max

Turbo's have a/r (air ratio) induction wheel measurements. The induction wheel puuls a certain amount of air then flattens out. If you go above the flat spot you will only burn more fuel because, the turbo can only pull a certain amount of p.s.i. Without going into lengthy dissc. you can put in perspective.

Rock04max
I am not up on how turbos work, are you referring to my 10mpg comment, if so is there a way to increase what the induction wheel pulls, resulting in higher fuel mileage when towing? Or am i way off base?
Thanks for your time on this, RR

[dieseldoc]

I think using Tow/Haul is more important in the new LMM engines with the emissions crap. We all know when a diesel is "lugging" at lower rpms it does not burn the fuel as efficiently - thus the black smoke the older diesels and big rigs make. I know we all like to see that, but in the new engines with the DPF's this will just result in more particle build up and more regen cycles and thus worse fuel mileage. The T/H mode keeps the engine in a more efficient RPM range for cleaner burning and likely will lead to higher MPG overall. Not a mechanic but a valid point IMO.