Allison Transmission Economy mode

[iluvuk]

I would like to hear opinions from those that have an Allison transmission with the Economy mode button on your DP. When do you use it? When do you not use it? Why or why not? Have you ever compared Fuel economy on the same route with and without Economy mode?

FYI I tend to use Economy mode almost always...the exception is if I want to downshift to pass someone on a steep hill. Other than that I have left it on. I am wondering if I am really helping my fuel economy or not. Look forward to your input.

[A Traveler]

I never bother to use it.

All it does is change the shift schedule at wide open throttle. With Economy Mode engaged, the transmission will upshift at a lower rpm when the throttle is in the floor. If the throttle is NOT wide open, it makes absolutely no difference whether it is engaged or not.

[Crasher]

I found that the difference in fuel economy while traveling cross country is insignificant at best. How you drive with your right foot will have more impact on economy than the eco mode. I rarely use it anymore.

[chuckftboy]

A Traveler is probably correct. I never felt any difference or got better mileage when I used economy so I simply never use it. I seldom feel the need to put the pedal to the metal, I figure not much point with a pusher.

[Ray,IN]

On advice from my son-in-law ( corporate maintenance manager for C to C trucking company) I turn on economy mode as soon as the engine starts. I have noted over several thousand miles of before eco and after eco mode runs, I get about 1/2 MPG more with eco on. I could probably do better if my right foot wasn't so heavy.
I do remember driver training in high school teaching to drive like there was an egg between your foot and accelerator pedal.

[FIRE UP]

The "Economy" mode means different things in different applications. For the most part, in Motorhome applications, it does change the way the trans thinks for you. The intent of it is to keep the rpms more constant, even in situations where, it's almost bogging the engine a bit, to try and eek out the maximum fuel economy. But, that, as you can read here, doesn't happen very often. About 98% of the folks that have it, NEVER use it, including myself.

But, when I said it means different things, it did with our fire trucks. The ECONOMY button in our shift pads was tied to 6th gear. If we didn't push that button, the trans would only use the first 5 gears, no matter how fast you wanted to go, just 5 gears. So, we trained all personnel (Engineers and trainees) to push that Economy button, right after startup. You just got into a habit of it, just like pushing all other buttons and switching switches, based on Code running or not.

As stated, I myself never, ever use it. I control that transmission, not it, for the most part. If driving normally, I let it do it's thing. But, when grades and or hills, or any situation where optimum torque/HP and cooling needs arise, I take over. Waaaaaaaaay better on performance etc.
Scott

[Finance]

You may get differing but accurate reports because of the different engines, transmission models, and generation of equipment involved. I use economy when I want to lower the shift points to prevent downshifting on rolling hills for instance. Or sometimes when the engine is cold and I want to just ease down the road and short shift. The economy mode on my 3000 changes more than just WOT shift points.

I don’t use it with the aim of fuel conservation much. However in my experience gear changing is the enemy of fuel economy, so it helps in that respect.

[Steve Ownby]

Originally Posted by FIRE UP

The "Economy" mode means different things in different applications. For the most part, in Motorhome applications, it does change the way the trans thinks for you. The intent of it is to keep the rpms more constant, even in situations where, it's almost bogging the engine a bit, to try and eek out the maximum fuel economy. But, that, as you can read here, doesn't happen very often. About 98% of the folks that have it, NEVER use it, including myself.



But, when I said it means different things, it did with our fire trucks. The ECONOMY button in our shift pads was tied to 6th gear. If we didn't push that button, the trans would only use the first 5 gears, no matter how fast you wanted to go, just 5 gears. So, we trained all personnel (Engineers and trainees) to push that Economy button, right after startup. You just got into a habit of it, just like pushing all other buttons and switching switches, based on Code running or not.



As stated, I myself never, ever use it. I control that transmission, not it, for the most part. If driving normally, I let it do it's thing. But, when grades and or hills, or any situation where optimum torque/HP and cooling needs arise, I take over. Waaaaaaaaay better on performance etc.

Scott

Great post! Thanks Scott. Couldn’t agree more.

[jimmy braden]

Yeah, you'd be better thinkin about the top gear selected on the shift pad - especially since most RVs dont spend time at any speed other than ~60 or 10-25mph. Make sure you dont lug it moving thru towns. 1150-1200 should be min for any IS series and probably for most cats or DDs.

[Quincy]

There is a constant fight between power and economy. You can not maximize both at the same time. Economy uses less fuel and power uses more fuel.

The mode button will have the trans shift at reasonable times with enough power to keep fuel usage at a minimum. For those with a heavy foot you wont get the maximum benefit of the torque capabilities of a motor until you up the rpms past where economic fuel use would be.

It seems many people will push the pedal to the floor when climbing a hill or accelerating to speed on higher speed roads.

If you do this then fuel economy goes out the window.

Keeping your foot just ahead of the acceleration when increasing speed is the most economical way to get to desired speed. And climb a hill. Pushing the pedal to the floor is totally unnecessary. (JMHO Of course).

The Allison also has two OD gears, 5 and 6. The torque converter locks at both 5 and 6 to avoid slippage. I don't see econo mode keeping the trans from shifting into 6th gear. 6th gear is the most economical gear to choose at the right speed. Again JMHO

Even Allison claims a six percent increase in fuel economy if using econo mode exclusively and that is with a professional driver paid to drive in the most economic way possible. Average drivers like us would not do that well which means the savings would be hard to notice.

So if WOT is the way you drive don't bother with econo mode you will negate any benefit it might provide. If you would like the most economical way to drive then do use it. But saying it is useless is definitely incorrect.

Again, JMHO

[Fiesta48]

I found we don't have enough power in almost all situations. Pushing eco only makes it worse. I can see ahead, the trans can't to anticipate hills. If you wait until it needs to downshift, it's too late. I use 5th a lot in hills, even left it there in repeated ups and downs. I never floor it.
I get a calculated actual 8.8 mpg on my 35k lbs ISL pulling an Accord. LBCU always reads 6-8% higher. Even in the Rockies this summer I averaged 8.6

[Mr_D]

The "Mode" button can be programmed many ways. Some trucks lock out 6th gear for around town use. Most MH's change the shift points to lower them under lighter throttle so the upshift sooner.
Lots of different ways to program them. Allison has publications that will help answer the questions.

[paddler1954]

When we had our previous coach with the 6.7L Cummins the Economy mode made a huge difference about 1/2 mpg. In our current coach, it seems to get maybe .2 or .3 mpg better. The difference, with the smaller motor it would force the transmission to stay in 6th (longer) when running in hills thus better mpg.

In our new coach, with the 8.9 L, it has enough torque not to need to downshift on the rolly-pollies. I also notice better economy in suburb driving situations, the economy mode forces the transmission into the highest gear possible thus better economy.

[1ciderdog]

I've put about 150K on my RV - sometimes using mode and sometimes not. I never noticed any difference in mpg.