Cruise control in tow/haul mode - Page 2 - Diesel Forum

DXprowler · 07-21-2008, 10:43 PM

Stymie.... how do you lug a motor that has an automatic transmission?? Sure with a handshacker it's easy enough to do, but with an auto and especially in Tow/Haul, it just doesn't happen!

Getting back to the original posters question... EGT temps go up with higher turbo pressure caused by more load. The result is higher rev's with the motor working harder with ALL temps rising. By staying out of cruise rev's can be kept lower resulting in lower temps. The Edge Insight is a great tool!

kghenson · 07-22-2008, 01:09 PM

Quote:

Originally Posted by Stymie

im not confused... i've been around diesels long enough to understand what lugging a motor does to egt's. Tell you what, hook up a pyro, run up the hill locked in od, and then let it drop a gear. See what happens...

jeez Stymie, your not only confused, your lost...LOL

It is an automatic, I'm not holding it in gear, I'm raising and lowering the speed a mile or 2 to help it stay in it's power curve. If it needs to shift it does, thats how automatics work. I'm just trying to influence it to stay in OD or to shift to OD by not asking it to go so fast.

It really isn't lugging at 2,000 rpm. If you have been around diesels so long you must know that.

Your implication that by slowing down to keep it in OD will hurt the tranny or motor makes no sense.

westvandude · 08-07-2008, 10:56 AM

You guys all have me confused. Last trip from Vancouver to the Okanagan (sea level to around 5300ft elevation and back down) with the Tymar I could hear noticeable surge (not crazy surge mind you ~2200rpm) with O/D engaged (unloaded no trailer just 4 people & luggage) 70mph up the steepest grades (top gear - no downshifting) and I saw just over 10psi boost and around 1100degF. Mind you that was leaving all cars in the dust behind me.

Anyway... at that high a load on the motor @ 2200rpm I'd almost consider that lugging it which is why you run into turbo surge and high egt's.

I'll be making the same trip next week but with 10,000lb 26' enclosed car hauler with a car and all the **** outta my buddy's house in it.

But definitely with cruise on I was giving it some throttle to gain speed before hitting uphill sections. That saves you fuel. I got 21mpg (imperial gal) unloaded overall @ 70-75mph avg speed, 5300ft elevation change.

So.... unless it's completely flat ground I'll be in Tow/Haul with O/D off and keep the rpm's up on the steep sections and watch the EGTs.

Any other suggestions?

Mark Kovalsky · 08-07-2008, 01:23 PM

Quote:

Originally Posted by westvandude

So.... unless it's completely flat ground I'll be in Tow/Haul with O/D off

If you're talking about the 2001 in your signature, no, you won't be in tow/haul. The 2003 model year was the first year Ford had tow/haul. Before that there was only a switch to turn off overdrive.

Vegas_Fergie · 08-07-2008, 04:35 PM

I use tow/haul and the cruise on flat ground w/shallow grades set at 60mph and it works great. I disengage the curise once I get into the mountains, though.

As far as someone being concerned about hurting the tranny or motor if the cuise causes the truck to downshift on a grade, that's what it's supposed to do to maintain speed. Also, I don't think it hurts the truck, but keeps the tranny from getting hot and egt's lower. If you have a heavy load and try and hold a higher gear up a grade, that will cause the tranny and egt's to run hotter. Basically, I leave it in OD and let the computer figure out when it needs to down shift, and this has worked well for me. The only time I manually shift is when desending an 8% grade, and I lock it in 2nd or 3rd.

westvandude · 08-07-2008, 09:02 PM

Quote:

Originally Posted by Mark Kovalsky

If you're talking about the 2001 in your signature, no, you won't be in tow/haul. The 2003 model year was the first year Ford had tow/haul. Before that there was only a switch to turn off overdrive.

Ok... but explain the difference please. Is it different gear ratio, converter lock, etc? Inquiring minds want to know.... not that I'd want one.

Mark Kovalsky · 08-08-2008, 08:00 AM

Tow/haul is a feature that was introduced with the TorqShift trans in 2003. You can tell if you have it because the button on the end of the shifter says TOW/HAUL instead of OD OFF.

Tow/haul changes the shift pattern, but does not turn off overdrive. It makes upshifts at higher RPMs, and it will make downshifts to help with engine braking. It also locks the torque converter a bit more than with tow/haul turned off.

wolfe14785 · 08-13-2008, 12:29 PM

The latest flash helps with the tranny shifting, when in tow haul it downshifts sooner than with it off, .5mpg diff in tow haul and 2mph diff at 70mph in cruise with it off (used handheld gps). I just did a trip towing with the new flash and it held cruise much better. I use tow/haul till I'm on the highway then take it off, I do like it in city driving.

The new flash also eliminates regen at idle, so no worry about the rpm's kicking up to 1200 when your backing a trailer into a tight spot, I almost wrecked my trailer in a campground once when this happened, had to shut my truck off 4 times because it kept going into regen when I was trying to put it into a really tight spot, I didn't want to sit there for 10min or more and wait for it to finish, besides that would piss off the other campers.