Aisin six speed question

[AH64ID]

Right after buying my '18 I started a log. I kept track of all miles and every drop used for over 6000 miles. Using that data, I ciphered that the EVIC value was right at 3.0 mpg high vs hand calculated. Now I dont need to hand calculate anymore as I just subtract 3.0 from the reading, and know that value is very very close to the actual number in the type of driving that I do. My $0.02.

Stock tires? Speedo accurate? That's the largest error I've ever heard of on a '13+ truck.

I've never had mine 3.0 mpg off, the biggest error was 2.2 and the only one above 2.0.

Figured I'd run some more numbers since it's all in excel. I have 21 samples so far.

Overall average is error 1.1 mpg, or 7.1% off
Standard Deviation of 0.6 mpg.

Like @SnoKing I have had it be closest to accurate when towing so I broke it down further

For tanks with 9-11 mpgs (8)
Average is 0.6 mpg, or 5.3%
Smallest error was .1 mpg, or 0.6%... best on record for difference and percentage
Largest error was 1.1 mpg, or 9.3%

For tanks with 12-14 mpgs (4)
Average error is 1.3 mpgs, or 8.0%
Smallest error was .6 mpg, or 4.3%
Largest error was 1.9 mpg, or 11.7%... worst percentage on record

For tanks with 15-17 mpgs (5)
Average error is 1.4 mpgs, or 7.7%
Smallest error was 0.8 mpg, or 4.7%
Largest error was 1.7 mpg, or 9.3%

For tanks with 18-20 mpgs (4)
Average error is 1.4 mpgs, or 7.0%
Smallest error was .8 mpg, or 3.9%
Largest error was 2.2 mpg, 10.5%..largest difference on record


I don't have as many miles on dad's '17, but it seems to be very similar. Both of our new trucks are FAR more accurate than our 3rd gens ever were.

I actually took a picture of the MPG calculator on the truck because I couldn’t believe how well the truck was doing on fuel.

First picture was 45 minutes before the second to prove I had the cruise set at 69 at that point.

Next time I do a trip with the truck, I will do hand calcs as well.

I took this one the other day. No traffic, no wind, and lost 150' in 18 miles. Not the longest sample, but was fun to watch.

 

[DeansRedRam]

My speed in my 18 I notice is off. When I say off I mean the digital speed is faster than the analog speedometer and I think the digital is correct.

 

[AH64ID]

My speed in my 18 I notice is off. When I say off I mean the digital speed is faster than the analog speedometer and I think the digital is correct.

Yes I would trust the digital over the analog, but they should match.

 

[DeansRedRam]

Yeah maybe one day I’ll stop by the dealer with the truck, strange.

 

[Mike Wenrich]

Since no one has mentioned the dead pedal problem I.E. torque management with the Aison, I must chime in with comments to the original person asking if their are any misgivings. In short, SOME Aisin equipped trucks have severe torque management built in and it's a PIA to drive these. Before you lay your money down, drive the truck you are going to buy and make sure you don't have a deadly lag in acceleration. Mine is 3-5 seconds depending on the gear and speed. RAM will not correct this problem and it does not occur on all trucks. Seems the 68RFE is not as affected. I just returned from a camping trip over the weekend where I had my camper on and towed a heavy trailer on curvy mountain roads. The lag was even more pronounced and as you wait 5 seconds to get power to move up the hill, it engages with a great amount of torque which then causes you to let off the pedal and go thru it all over again. There are those on this forum that say it does not exist but many others than myself have the issue. Other than that Mrs. Lincoln it's a wonderful truck. Wish I could sell it without taking a huge loss.

 

[Cummins12V98]

I fill to the top and hand calc every tank. Typically I am .4 lower than computer. When towing and head winds/mountains at 7.5 I am nearly right on.

 

[jhenderson]

I’ve got 135,000 on my 15 and hand calculated every tank. The lie-0-meter has been consistently optimistic by an average of almost 2 mpg and over 3 mpg a number of times. Towing or empty.

 

[MRFost]

My truck is stock, and almost all of those first 6000 miles was very lightly loaded and driven gently. I suspect that the folks that say the mpg indicator is much closer to actual have either a heavier load, more stop and go, shorter trips, or other conditions than I. My driving to/from the office as an example is 20 miles, of which 17 miles is relatively level interstate.

Some might ask why I need such a truck to use as a cruiser...and that is irrelevant to the discussion...I have a good explanation for that question and that is another topic for another day. I do load my truck heavily as need arises...and the truck is a tool to me.

I'm convinced the mpg indicator reads consistently 3.0 mpg FOR ME.

 

[dieselshadow]

Just completed this science experiment yesterday. Drove from OKC to Nashville for a total of just over 700 miles almost nonstop. I ran empty, cruise set on 75 when possible. Ran into traffic in Little Rock and was delayed in several construction areas and one accident. Overall not too bad. Pay attention to the clock, elapsed time, odometer, and average speeds.

Later that day.... only one quick coffee induced pit stop at a interstate rest stop.

I did manage to get another 1/2 gallon in the tank after it clicked off in that pic. It wouldn’t let me put anymore in. Seemed like that pump was very sensitive.

Then at the end of the trip.... BTW, forgot to get a pic of the pump, there was a good sized line and I pulled forward to be courteous and failed to get a pic.

Your mileage may vary.....

 

[dieselshadow]

I will say it doesn’t take much fuel to upset your calculations. Pair that up with the funky filler neck and the huge variety of diesel pumps out there, it’s very hard to get very accurate number consistently. Diesel foams up as it’s pumped, moreso the faster the rate and smaller diameter nozzle. I tried to keep things level, but there’s just too many variables that are out of anyone’s real control when calculating fuel mileage.

My EVIC seems to be close enough to not really worry about it. I mean after all, what are you gonna do about it? When it needs fuel, you put some in right? I still hand calc most fuel stops, but I don’t lose sleep over it. I just drive it. It’s not a Prius nor is it a big rig.

Sure would be nice if it got better mileage, but I’m not really complaining. It’s the price you gotta pay when you want to play.

 

[AH64ID]

I will say it doesn’t take much fuel to upset your calculations. Pair that up with the funky filler neck and the huge variety of diesel pumps out there, it’s very hard to get very accurate number consistently. Diesel foams up as it’s pumped, moreso the faster the rate and smaller diameter nozzle. I tried to keep things level, but there’s just too many variables that are out of anyone’s real control when calculating fuel mileage.

My EVIC seems to be close enough to not really worry about it. I mean after all, what are you gonna do about it? When it needs fuel, you put some in right? I still hand calc most fuel stops, but I don’t lose sleep over it. I just drive it. It’s not a Prius nor is it a big rig.

Sure would be nice if it got better mileage, but I’m not really complaining. It’s the price you gotta pay when you want to play.

Not to mention that 1 tank filled differently will effect the mpg readings on that tank, and the next one.

 

[SnoKing]

Pair that up with the funky filler neck and the huge variety of diesel pumps out there, it’s very hard to get very accurate number consistently.

The one time my truck pee'd it's pants on the ground was with one of those commercial truck nozzles that flows 3 or 4 times the flow of those car/pickup size ones.

 

[Cummins12V98]

When mine clicks off I slowly fill and have nozzle retracted to the max I can without closing flapper. When I see a drip on the ground it's full to that same level every time! So when I hand calc I get an accurate reading every time unless the fill location is sloped. If my puter says 15.0 you can bet my hand calc will be 14.6.

My 01 I fill right to the top of the neck every time.

 

[jhenderson]

When mine clicks off I slowly fill and have nozzle retracted to the max I can without closing flapper. When I see a drip on the ground it's full to that same level every time! So when I hand calc I get an accurate reading every time unless the fill location is sloped. If my puter says 15.0 you can bet my hand calc will be 14.6.

My 01 I fill right to the top of the neck every time.

Fill site sloped? When’s the last time you went to a gas station that the pumps weren’t level? More important would be the same pump each time for the same measure and automatic pump nozzle . I fill at the same pump 90% of the time using the same technique each time. Very repeatable.
I Do Not put fuel on the ground. I wouldn’t want someone to do it in my station so I’m careful not to do it in theirs.

 

[Wiredawg]

Friends,

This is unique mostly to me and others with tow bodies on C&Cs. When filling my 5500 OEM tank, the nozzle is mostly horizontal for approx. 18 inches back, so I'm careful to listen for the change in the sound as fuel starts filling the filler tube. I stop it there. Then, I open the drain valve on my 60 gallon aux tank and fill it. In the time it takes to fill it, except at high flow truck stops, the OEM tank is full. If I'm traveling, I top off the aux tank to the very top. If not, I stop the first time it clicks, allowing for expansion.

The first time I filled it though, the auto stop didn't work (broken) on the pump valve AND there was this terrible diesel tsunami that dumped about a gallon on the ground. After I was done filling, I put a bunch of paper towels on it, and went inside to tell the attendant what happened. They said they knew to auto stop was broken; i mentioned putting a sign up and they just blew me off.

Anyhoo, being fully competent at filling MY truck, I don't spill even a drop, just like in the mens room, a couple of shakes is all you need to not drip.

Cheers, Ron

 

[GJolicoeur]

I owned a 2013 dually with 4.10 gears and the 68RFE transmission. I towed a 43' toy hauler which, when loaded with small car, water, etc., weighed in at 20,000 lbs.
The truck was rated to tow around 23,750 lbs.
I owned a number of trucks with manual transmissions, and avoided the automatics since they were usually not capable of supporting the greater loads and full output of our Cummins engines.
The 68rfe was my first auto transmission in a truck. I was pleased with the gear ratio spread, but was not happy with the flare when upshifting. I would floor it pulling back onto the highway, and I couldn’t get it to downshift if the engine speed was above 2200 rpm. That was because, when it went to upshift, the revs would climb to 3000 rpm in a flare, shift, then lock again.
That all stopped with the Aisin - shifts were quick and positive - but not brutal. After several hundred miles towing when new, the transmission learned my usual throttle demands and shifted smoothly from then on.
I checked the towing capabilities with the different axle ratios and went with the 4.10s since I got the greatest towing weights with it. 3.42s were only rated for around 16,750 lbs. while the 4.10s could tow 31,000 lbs.
Guys were worried about the ultimate revs on the highway - and I’m happy to say that the revs with the 4.10s and the Aisin were actually lower than my manual Gen 3, 2004 one ton and 3.73 axle ratio.
70 miles an hour in 6th gear saw rpms around 1750. Empty mileage hovered around 19 mpg (Canadian, hand calculated) and between 9.5-11.5 towing (depending on which way the wind was blowing).
There was some talk about the power of the exhaust brake - my 2016 is twice as good as my 2013. I could take my foot off to coast into the highway rest stops with the trailer, and the exhaust brake would slow the whole 30,000 lbs. from 70-25 miles per hour by the end of the ramp. I would only have to touch the brakes to negotiate the corner into the parking area. The exhaust brake worked down to about 19 MPH in Tow-haul with the Aisin smoothly downshifting and relocking in each gear to maximize the stopping power.
So, don’t hesitate, the extra money for the Aisin was well worth it.

 

[Cummins12V98]

"3.42s were only rated for around 16,750 lbs. while the 4.10s could tow 31,000 lbs."