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Allison Economy Mode


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#1 wolfe10

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Posted 24 April 2009 - 11:59 AM

ALLISON MODE BUTTON

There are TWO TOTALLY DIFFERENT "LET THE TRANSMISSION CHOOSE THE CORRECT GEAR" MODES/PROGRAMS in the Allison ECU which is the "electronic brain" controlling shifting and other functions.

In ECONOMY MODE, the transmission will not downshift even at WOT (Wide Open Throttle) until the engine pulls down to peak torque RPM in some application and 200 RPM lower that "regular mode" in others.

In REGULAR MODE, the transmission WILL downshift much earlier (to maintain higher engine RPM).

ONLY at higher throttle positions is there any difference, so on flat ground you will NOT notice any difference (except accelerating from a stop IF you are at or close to wide open throttle).

It can make a BIG difference in rolling hills. If you are in rolling hills and regular mode (particularly with the cruise control on), it is common for the transmission to shift down to 5th on the uphill and back to 6th on the downhill. Repeat this process hundreds of times. In economy mode, you will stay in 6th gear unless the hill is so steep or so long that the engine can not pull it without dropping below peak torque RPM. If you can pull a hill in a higher gear (lower engine RPM) AND the engine does not overheat, THAT IS WHAT CATERPILLAR, CUMMINS, DD, ETC RECOMMENDATION FOR THE MOST ECONOMICAL WAY TO CLIMB A HILL with a modern turbo, after-cooled diesel engine.

If you know you will need a lower gear because of the steepness of the grade and/or are engine temperature is rising higher than thermostatically controlled temperature, if driving in economy mode, use the down arrow to drop a gear (this is what I do) or switch out of economy mode. Be sure to switch back into economy mode when past the steep section, or agree to pump extra fuel in the tank.

IF your engine begins to overheat, your HP/weight ratio is low OR if it irritates you to loose a few mph on a hill in the name of saving fuel, in the hills, by all means drive in regular mode.

It confuses me to hear people advocate driving in economy mode only on flat ground, as there is not 1% difference in shift RPM's between regular and economy mode on flat ground, excepting accelerating from a stop if you use WOT.

Every time you start the coach, the transmission is in regular mode. This is the default setting. IF you push the mode button, it goes to "economy mode" AND the light illuminates.

There is no "absolute" on how much difference in fuel economy driving in economy mode will have. On flat ground where you will be in 6th gear irrespective of what mode you are in, there will be ZERO difference. The MOST difference in mileage will be in rolling hills, where in regular mode, particularly if on cruise control you will start up a hill in 6th gear, go to WOT in 6th gear, downshift of 5th gear still at WOT (WHERE IT IS USING A LOT MORE FUEL). After the hill is crested, the transmission will up-shift to 6th, then likely coast a little in 6th gear (unless you are driving with the exhaust brake on-- if you are it then applies the exhaust brake AND downshifts TOWARD the pre-select gear which is generally either 2nd or 4th).And so on 6-5-6-5-6-5-6-5.......

A modern turbo inter-cooled diesel is much more efficient at low RPM high throttle settings. This is NOT my opinion. It is stated in just those words in most modern diesel's Owner's Manual.

Note: In either mode, you are free (and welcome) to use the up and down arrows to PRO-ACTIVELY choose the correct gear. You can not screw anything up-- even if you down-arrow to 1st gear at 70mph, the transmission understands that you meant "please downshift to the next lower gear as soon as the engine RPM will not exceed the pre-set amount. Then downshift again when safe....."

By the same token, you can shift between regular and economy mode as often as you want with the transmission in any gear when you make the change.

OPINION: I drive in economy mode 99% of the time, including in REAL mountains, but use the up and down arrows to choose the proper gear. I use regular mode ONLY when I am willing to say, "I am willing to throw a lot of fuel away to gain a little performance." When passing on 2 lane roads, THIS IS the case.

Brett Wolfe
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#2 Guest_Wayne77590_*

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Posted 24 April 2009 - 09:32 PM

Knowing "nothing" about the Allison transmissions, it took me some time to find any information in the manual and the first time out and back I didn't even know about pressing the "mode" button. So I was working on the WAG principle. After reading the manual I was working on the SWAG principle. (Anyone needing information on WAG and SWAG, PM me.)

Brett,
I found your article very informative. I already drive with the mode in economy so I'm driving like you. (Is that good?)

Thanks.

#3 -Gramps-

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Posted 26 April 2009 - 06:35 PM

The mode button doesn't work with all coaches. It doesn't do anything with my chassis.
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#4 wolfe10

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Posted 26 April 2009 - 08:47 PM

The mode button doesn't work with all coaches. It doesn't do anything with my chassis.


I am familiar with the Allison 3000 and 4000 series. The mode button certainly functions as described on them.

I do not know if/how the mode button functions on the gasoline chassis with smaller Allisons.

You might call Allison:

Allison help line 800 252 5283

And to verify mode button function, next time you are accelerating from a stop in regular mode (Mode OFF), note the max RPM's in each gear before it up-shifts when you are at WOT (Wide Open Throttle). Repeat with mode button ON. You should notice a real difference in max RPM before the shift, with it shifting earlier (lower RPM) in Mode ON.

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#5 DougC

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Posted 28 April 2009 - 04:41 PM

Brett,
Good information, the best explanation I've read about the Allison 3000 mode button.

Thanks.

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#6 DougC

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Posted 28 April 2009 - 05:22 PM

Brett,

Again thanks for the Allison information.

I have another question. my 2003 Newmar KS has 32,310 miles on it which is about 5,500 miles on average driven per year (not very much.) Ususally I just get in the RV, turn the key on and put it into gear (I've never used the economy mode).

Now I'm planning the 7-8,000 trip in June and would like to get the best performance out of the engine/transmission and also not abuse the engine/transmission.

So I plan to use the economy mode and down shift as needed. When in mountains I'll move into regular mode. I usually leave the exhaust brake on, which I find helps both in stop and go traffic and coming down a hill.

My question is about accelerating and general highway driving. From a complete stop is it better to slowly depress the gas pedal to come up to speed or to fully depress and let RV come up to the appropriate speed (safety first) and then back off the pedel?

Then, for highway crusing, again safety first along with speed limits, does the Cat 3126 perform better at 60, 65, or 70 mph? While the RV will get up 75 mph, I find 65 mph is a comforable highway speed. The Michelin tires 275/70R22.5 I think are rated for 65 mph.

Also, I'm told that when coming off the highway that the engine should idle/cool down a few minutes before it is shut off. Does that make sense?

Thanks again,
DougC
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#7 -Gramps-

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Posted 28 April 2009 - 10:03 PM

Wolfe10,

My Chassis manual says the mode button has no function.
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#8 wolfe10

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Posted 01 May 2009 - 04:33 PM

Brett,

Again thanks for the Allison information.

My question is about accelerating and general highway driving. From a complete stop is it better to slowly depress the gas pedal to come up to speed or to fully depress and let RV come up to the appropriate speed (safety first) and then back off the pedel?


Then, for highway crusing, again safety first along with speed limits, does the Cat 3126 perform better at 60, 65, or 70 mph? While the RV will get up 75 mph, I find 65 mph is a comforable highway speed. The Michelin tires 275/70R22.5 I think are rated for 65 mph.

Also, I'm told that when coming off the highway that the engine should idle/cool down a few minutes before it is shut off. Does that make sense?

Thanks again,
DougCpedalcruisingcomfortable


Doug,

Best MPG when accelerating from a stop is to accelerate slowly until you reach 6th gear.

Best economic cruise speed with the 3126 is between 1500 and 1650 in 6th gear. Faster is OK, but WILL use more fuel.

And if coming off the highway, you should idle the engine for about 3 minutes to cool down the turbo. For 99% of the CG's we pull into, by the time you pull up to the office, you have ample cool down time and can turn it off. It is on-freeway rest stops and fuel stops where you are going from highway speed to stopped that you have to pay attention to this.

For more information on driving economically, read this Caterpillar Document:

https://ohe.cat.com/.../7/LEGT5364.pdf

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#9 Cooxie1234

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Posted 03 May 2009 - 01:50 PM

Hi

I have a 2005 KS Pusher 330 Cummins and Allison. This push button thing total confuses me! Give me 9 speed manuel any time.
I can't seem to feel when I need to downshif on the climb or if it is auto shift. I'm short, so I have to look over and behind my left arm to see the mode. Do I have the economy? I down shift as I get steeper, and also use my jake down hill and stop and go. I think the worst pull have been on so far is HWY 160 from I-15 in Vegas to Pahrump NV. That was work! The worst road I wrongly got on was Hwy CA 178 from Lake Isabella, CA to Bakersfield, CA. Not for the weak of heart! :rolleyes:

Thanks
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#10 wolfe10

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Posted 03 May 2009 - 02:39 PM

Hi

I have a 2005 KS Pusher 330 Cummins and Allison. This push button thing total confuses me! Give me 9 speed manual any time.
I can't seem to feel when I need to downshift on the climb or if it is auto shift. I'm short, so I have to look over and behind my left arm to see the mode. Do I have the economy? I down shift as I get steeper, and also use my jake down hill and stop and go. I think the worst pull have been on so far is HWY 160 from I-15 in Vegas to Pahrump NV. That was work! The worst road I wrongly got on was Hwy CA 178 from Lake Isabella, CA to Bakersfield, CA. Not for the weak of heart! :rolleyes:

Thanks
Cookie


Cookie,

Indeed, your Allison 3000 series 6 speed transmission has a mode button as I described above (first post in this thread).

And NO transmission is PROactive. Only you can see that you are going from down hill to an 8% upgrade and need to downshift to keep up speed. If you are comfortable with a manual transmission, use the UP and DOWN arrows to select the gear YOU want.

And with a Cummins 330 HP, you will not have a Jake brake (also known as an engine compression brake). The Cummins ISL is the smallest engine with an option of a Jake brake. You will have an exhaust brake, though it could be manufactured by Jacobs Corp-- a little confusing.

If your shift pad is MIS placed (my opinion-- if it does not fall readily to hand without requiring you to take your eyes off the road to find it), consider moving it. Most shift pads come with plenty of cabling to allow you to relocate it to a more convenient position.

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#11 Cooxie1234

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Posted 03 May 2009 - 04:12 PM

Your right, it is a Exhaust Brake..old habit to call it a Jake Brake. When I start it up again I will check out this economy setting and read up on it.

Thanks!

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#12 mbisson

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Posted 29 September 2009 - 09:46 PM

Brett

Thank you for putting in this information. I am a Newb, so all the info I can find is helpful. I have been using my new(to me) Kountry Star with a cat 330 with the economy mode selected. I just am not sure when I should push the button to downshift. What is the best RPM range for this setup.

Thanks
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#13 wolfe10

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Posted 30 September 2009 - 08:25 AM

Mike,

Welcome to the FMCA Forum.

Two different answers-- dependent on whether your engine coolant temperature is OK or if you are starting to overheat.

If coolant temperature is not a problem, Caterpillar's recommendation in writing for max MPG is to allow the engine to lug down to peak torque RPM before downshifting. That is 1,440 RPM for your engine. And economy mode should be programmed to do just that-- shift down when you are heavy into the throttle and RPM drops to 1,440 (or a little above). Said another way, the Allison ECU is programmed to do what Caterpillar recommends.

Obivously, if a few more miles an hour up that hill are important to you (AND you are willing to pay for the drop in fuel mileage) downshift, raise engine RPM and you will go a FEW MPH faster. For an excellent discussion of performance and MPG, read this Caterpillar Corp document (makes good reading irrespective of what brand engine you have-- physics is physics): Understanding Coach (RV) Performance

If coolant temps start to rise, raising engine RPM (and backing out of the throttle a little) will lower engine temperatures. It takes XX HP to go up a hill at YY speed. And producing that HP produces a certain heat load. If the engine is turning over at 2,100 RPM instead of, say, 1500 RPM, the water pump and fan are turning a lot faster and can dissipate a lot more heat load.

Also, be sure to read this thread to reduce overheating: http://community.fmc...p?showtopic=288

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#14 mbisson

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Posted 30 September 2009 - 09:19 AM

Thank you for the info. No problems with overheating yet. Went to AZ two weeks ago, drove through 110 degree heat.
I now find myself looking for threads you have started.

Thnaks again.
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#15 wolfe10

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Posted 30 September 2009 - 10:32 AM

Thank you for the info. No problems with overheating yet. Went to AZ two weeks ago, drove through 110 degree heat.
I now find myself looking for threads you have started.

Thanks again.
mike



Mike,

The FMCA Forum makes it easy to search for any other member's TOPICS or POSTS.

On the upper left of a member's post, scroll over their NAME (wolfe 10 in my case).

You will see a "down arrow" appear when you scroll over their name. CLICK on it.

Scroll down to "Find Member's Topics" or if you want to view all of a member's posts to "Find Member's Posts". CLICK on it.

That will bring up a list of that member's TOPICS or POSTS starting with the most recent at the top.

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#16 skyking8

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Posted 07 October 2009 - 11:06 AM

My rig has a CAT C7 with Allison 6 sp. There are some significant RPM ranges that the book discusses with respect to manual shifting in differing terrain. In order to take advantage of RPM and not put stress on the transmission by improper shifting, I marked my gage with colored tape as a handy reference for staying within the proper RPM values.

With the gage marked, I have found that the statement "And economy mode should be programmed to do just that-- shift down when you are heavy into the throttle and RPM drops to 1,440 or a little above)" doesn't always happen. I am wondering if there is a terrain variable. Meaning that on steeper grades, you will need to monitor RPM and manually shift before it drops below that magic number.

Good info on the mode button. I've never found much difference in fuel mileage using the mode button, but it certainly does eliminate the need to manually downshift when I come to the hill that's just a bit steeper than the others. If no other reason that was mentioned, I can keep my eyes on the road.
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#17 wolfe10

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Posted 07 October 2009 - 11:40 AM

With the gage marked, I have found that the statement "And economy mode should be programmed to do just that-- shift down when you are heavy into the throttle and RPM drops to 1,440 or a little above)" doesn't always happen. I am wondering if there is a terrain variable. Meaning that on steeper grades, you will need to monitor RPM and manually shift before it drops below that magic number.

No, the Allison ECU can not sense grades, only RPM (both output and engine /input) and throttle position.

So at the same throttle position it SHOULD hold that gear down to the same RPM each time with that RPM being different in regular vs economy mode.

BUT, if you were at, say 85% throttle vs 100% throttle, it SHOULD be different.

Brett Wolfe
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#18 ChunkyBeastracin

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Posted 20 January 2010 - 07:49 AM

Well, still just getting my feet wet with the operation of our first diesel. I decided to try the economy mode on the Allison 6-speed transission to see if it really made a difference.

We drove over 300-plus miles towing our car down to Ignacia, Colo., without the economy mode. On the way back we took the exact same route, which went over several steep passess up to 11,000 feet throught the Rocky Mountains. Wen we finished our trip we got an extra 1 mpg using the economy mode. I really did not notice too much difference in the speed we were able to maintain, other than the transmission seemed to work a lot less hard. To me, it's an easy decision on which mode to use.
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#19 TBUTLER

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Posted 20 January 2010 - 01:09 PM

I use my economy mode all the time - unless I forget to select it. I was told once that the economy mode was planned to be the default mode but that too many people wanted the better performance. The person who said this claimed that people who were used to driving gasoline engines wanted to hear the higher RPM's they were familiar with instead of the low rumble of an efficient diesel engine. Your results are consistent with what I have found with our rig.
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#20 wolfe10

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Posted 20 January 2010 - 07:53 PM

We will see a wide range of "improvements" in MPG reported when using Economy Mode over that using Regular/Performance Mode.

And that is reasonable-- as Mode makes virtually no difference on flat ground since the transmission is not down/up shifting whether in regular or economy mode.

But in rolling hills/mountains, economy mode can minimize/eliminate the 5-6-5-6-5-6... shifting on each grade. Under these conditions use of economy mode can significantly improve MPG.

Brett Wolfe
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