Better Gas Milage and Shift Lock on e-350 based RV?

I traded an 1999 f350 7.3 (4r100) with a camper for the e450 ford v10
class c
the diesel would pull Mont Eagle in Tennessee without down shifting

but..the 7.3 gets it's max torque at 1600 rpm vs. the v10 at 3500 or so rpm..

I agree with previous comment...lugging is no good for engine or tranny.

it has taken me a little getting use to with the shift patterns of the v10 vs the 7.3 ...and the fuel mileage 13.5 vs 8.5

but everything has its down side.

but I do enjoy the v 10 and it does have a good reputation.

DrewE wrote:
I think it also adjusts some of the logic for when the torque converter is locked up with the goal of reducing transmission temperatures and such.

That's where I think any gas mileage savings might come from by staying in TOW/HAUL mode more - at least with respect to the newer TorqShift transmission. Less torque converter slippage because the TorqShift stays longer in gears has got to have some positive impact on mileage. Torque converter slippage - it's other advantages notwithstanding - is wasteful, hence the additional transmission heating that results from slippage.

By the way, with the cruise control turned ON in hilly country, the TorqueShift does downshift automatically to maintain the set speed when going downhill ... even when the tranny is not in TOW/HAUL mode. Bottom line - the TorqShift tranny automatically downshifts when going downhill whenever it's in TOW/HAUL mode or whenever cruise control is turned ON.

rooney x2

We're talking about E4OD and its successor 4R100. Neither has Option #5.

I've driven 5R115 "TorqShift" in a Class C and an F350 with heavy BigFoot slide-in. TS is smarter than a trick pony. Both were V10's and I drove both in Alaska where it's hilly. Both Fords had better shift behavior than 4R100 in normal mode, and much better in TH mode.

Intentionally left this out since the question wasn't about TorqShift. It behaves way better than its predecessors, and I imagine GM's Allison and probably also GM's six-speed HydraMatic have similar bags of tricks.

Read Drew's post. He's correct in that the newer transmissions have their shift patterns altered by the tow/haul mode. The older transmissions (like the one the OP has, the E4OD) the tow/haul mode only locks out the top gear. So the tow/haul mode will not improve his mpg, in fact it will most likely make it worse. It will eliminate down shifts though, but only because it never upshifted.

As to whether or not you should use tow/haul mode, well that depends on terrain and whether or not you are putting strain on the transmission. I've hauled extremely heavy loads and not had to use it. Then I've hauled light loads and needed it. If you transmission is cycling through the gears a lot and seems to be hunting for the right gear, put it in tow/haul. If it's not doing that then it's not needed.

pnichols wrote:
TOW mode .....
It seems to me that running in TOW mode all the time is the correct way to go since a motorhome heavily loads the chassis all the time - just as if an E-Series delivery van was full of cargo and hence was kept in TOW mode while loaded.

This is my thinking. In tow mode I never (95%) ever have to step on the gas to go over a overpass or small hill and the engine never sounds like it is over worked. When out of tow mode on a lot of overpasses it drops a gear or revs the engine to get over it. I have the V-10 2008 32' Class C and tow a Colorado most of the time when traveling.

Maybe a Certified FORD mechanic could share their thoughts on this.

TOW mode on our E450 2005 5-speed (6 speeds internal) TorqShift does not eliminate OD ratios.

TOW mode only lengthens out the time in each gear when accelerating. Once at cruising speed, the TACH indicates the same RPM at any given cruising speed whether in TOW mode or not.

It seems to me that running in TOW mode all the time is the correct way to go since a motorhome heavily loads the chassis all the time - just as if an E-Series delivery van was full of cargo and hence was kept in TOW mode while loaded.

rooney77 wrote:

JAXFL wrote:

I have tried #5 and it stops some of the shifting

#5- You want to run Cruise - Push in the TOW button. You experience no downshifting even on overpasses. You get a very steady road speed. But it does not seem to do anything about increasing MPG.

I'd assume that would lower you're mpg. Basically tow mode just eliminates the OD (4th gear) so you're engine will be at a higher RPM at speed, same as if it downshifted.

On (some?) older Ford chassis, there's an overdrive off button on the end of the shift lever that does nothing more or less than disabling overdrive. That's what I have in my class C, with the venerable 4 speed transmission. (It's correctly labeled as "overdrive off", not as "tow/haul.")

On newer ones with the 5 speed transmission, the button is labeled tow/haul and has rather different effects. It doesn't entirely lock out overdrive, but it alters the shift point programming to (as I understand it) more aggressively downshift, less aggressively upshift, and to downshift automatically in response to braking when going down grades. I think it also adjusts some of the logic for when the torque converter is locked up with the goal of reducing transmission temperatures and such. This tow/haul mode is quite effective for heavy loads, much more so than a simplistic overdrive lockout.

Realistically, fiddling with transmission shift points isn't going to yield much better gas milage for a given speed and terrain. At least up to a point the engine is a little more efficient at lower RPMs, but the differences are comparatively small. Air resistance is proportional to something like the fourth power of speed, so slowing down a little results in a big savings. Air resistance at 72 mph is something like twice that at 60 mph. In other words, slowing down will have a much larger impact on gas milage than most any other easily made change, assuming the chassis is in proper repair.

I have the same Ford E-350 on my 1995 Callista Cove. I have always been told NEVER to go up hills/inclines with cruise control on. Also to turn off the overdrive and leave it in the drive position.

JAXFL wrote:

j-d wrote:
Check this Cruise Control Downshifting Thread.

I've driven Class C's with the three-speed C6, four-speed 4R100, and five-speed 5R110 TorqShift. The E4OD you have is pretty much same as 4R100, but I haven't driven that specific version.

My guess is the thread linked above pretty much explains what goes on with a Ford automatic and cruise control. Let me try four scenarios:

1. You want to run Cruise - You experience LOTS of downshifting. In return for the noise you get a very steady road speed.

2. You want to run Cruise but reduce downshifting - Anticipate grades by increasing speed with the accelerator. If you increase speed enough, it'll work. If you don't, the transmission will downshift according to cruise control rules.

3. You want to keep speed as steady as Cruise but you're willing to use your foot on the accelerator - A little less downshifting, and you get pretty close to the speed control the cruise affords.

4. You're willing to sacrifice a tight speed range to avoid downshifts and will use your foot to do it. Anticipate a grade by speeding up 5MPH or so, accept a loss of 5MPH or so, and you'll have much less downshifting. But your speed will be 5 or more above, and 5 or more below, your desired speed.

I just drove ours 600 miles. I tried them all outbound and used 4. all the way home. 4. was much less stressful. Too bad Ford doesn't allow some form of adjustment, but Cruise is useless on any terrain hillier than Texas.

I have tried #5 and it stops some of the shifting

#5- You want to run Cruise - Push in the TOW button. You experience no downshifting even on overpasses. You get a very steady road speed. But it does not seem to do anything about increasing MPG.

I'd assume that would lower you're mpg. Basically tow mode just eliminates the OD (4th gear) so you're engine will be at a higher RPM at speed, same as if it downshifted.

j-d wrote:
Check this Cruise Control Downshifting Thread.

I've driven Class C's with the three-speed C6, four-speed 4R100, and five-speed 5R110 TorqShift. The E4OD you have is pretty much same as 4R100, but I haven't driven that specific version.

My guess is the thread linked above pretty much explains what goes on with a Ford automatic and cruise control. Let me try four scenarios:

1. You want to run Cruise - You experience LOTS of downshifting. In return for the noise you get a very steady road speed.

2. You want to run Cruise but reduce downshifting - Anticipate grades by increasing speed with the accelerator. If you increase speed enough, it'll work. If you don't, the transmission will downshift according to cruise control rules.

3. You want to keep speed as steady as Cruise but you're willing to use your foot on the accelerator - A little less downshifting, and you get pretty close to the speed control the cruise affords.

4. You're willing to sacrifice a tight speed range to avoid downshifts and will use your foot to do it. Anticipate a grade by speeding up 5MPH or so, accept a loss of 5MPH or so, and you'll have much less downshifting. But your speed will be 5 or more above, and 5 or more below, your desired speed.

I just drove ours 600 miles. I tried them all outbound and used 4. all the way home. 4. was much less stressful. Too bad Ford doesn't allow some form of adjustment, but Cruise is useless on any terrain hillier than Texas.

I have tried #5 and it stops some of the shifting

#5- You want to run Cruise - Push in the TOW button. You experience no downshifting even on overpasses. You get a very steady road speed. But it does not seem to do anything about increasing MPG.