Can New Sumitomo Tires Cut Fuel Mileage??....& UPDATE - Human Error!

[willbo777]

We have a routine in our 19 years of full timing.  I pull into the truck stop, pull on the braking brake and check for level, one to be sure I'm not leaning toward whichever side I am pumping on, then with the manual air leveling tilt the coach away from the pump.  Then I go out and fuel, meantime my wife is marking down our mileage since last fill up, resetting the Aladdin fuel screen, and then when I finish she notes the exact gallons, and presses travel.  Then I usually come back in, stop in the rest room, and then I pull out, at travel.  Even if I would forget, the Valid system defaults to travel when the parking brake comes off and I put it in D.  I don't think you could actually move more than 50 yards at a very slow speed before you'd be at travel even if you forgot to press the button.  I have a 35 year aviation background and believe in checklists and flows, not saying we have never forgotten between the two of us, but knock on wood, it hasn't happened yet.

[Steven P]

21 hours ago, saflyer said:

Mea culpa time, maybe. After fueling yesterday I moved the coach a few feet to a spot where it tilted a little to the right. Got out to find fuel pouring out of the right hand side. I quickly opened the fueling door to find the tank cap off and hanging from its lanyard. In most cases I fuel on the left side almost always but I guess I fueled on the right side in June which was the last time before the new tires. 
Now this doesn’t necessarily explain all of the mileage loss but it does explain some, possibly. Confounding factors: (1) I found the right side of my toad covered in fuel after one but only one refueling. (2) I would think after the loss of a few gallons fuel would no longer come out the open fill line. I did check for leaks multiple times and found no evidence of any. 
I won’t have a chance to do another mileage test until our next trip in February. Will update then.

Ed      
I thought I was wrong once but I was mistaken.     
 

That happened to me once before.  I recall noting the fuel mileage loss. The diesel smell after refueling grabbed my attention and made me check the other door.  In my case, I had opened it to add a fuel additive and forgot to cap it.  Lesson learned. 

[Guest Ray Davis]

 

I think we can take from this debate that it ain't the tires and any degree of MPG accuracy has got to be done systematically over an extended amount of time, miles, and fill-ups.  Otherwise, we're guessing or being misled by something.

I know that many members document every drop but that's not me, I prefer to rely on my Trip-Tek, It's more accurate than I would probably be anyway.   I get in the 8 mpg range & that makes me happy, more would be better though.

Prices are down around here so it's sort of like more MPG.   Under $4.00 & gas under $3

[Ivan K]

9 minutes ago, Ray Davis said:

Prices are down around here so it's sort of like more MPG.   Under $4.00 & gas under $3

I wish I would see this again, that was one of the few painless fill ups. I had no worries about MPG then.

[Guest Ray Davis]

6 minutes ago, Ivan K said:

I wish I would see this again, that was one of the few painless fill ups. I had no worries about MPG then.

Looks like you framed it and hung it on the wall, or should,  I couldn't blame you.

I noticed that was back in 2020,  the good old days.  LOL

[nvrtoofast]

Come Baaaack 2020! I did 15K miles in 2021 and while they weren't that good. They weren't 2023 bad. Nice memory!

[96 EVO]

I'd be happy to buy a liter for $1.339.

Right now I'm paying $2.19 per liter! ($8.27CAD gallon) ☹️

Edited October 17, 2023 by 96 EVO

[dl_racing427]

58 minutes ago, Ivan K said:

I wish I would see this again, that was one of the few painless fill ups. I had no worries about MPG then.

PBP = Pre-Brandon Price

[cbr046]

23 minutes ago, Dr4Film said:

We could fix that in a heat beat by using our own domestic oil instead of purchasing oil from countries that hate our existence and want to wipe us off the face of the planet.

Let's not go down that rabbit hole and get this long and confusing thread locked.  BTW, Venezuela just signed an agreement to start shipping us oil.  Not sure what that will do with OPEC pricing but should put negative pressure on price / barrel. 

EDIT…. 

THANKS…..   Anyone recall the old joke.  Young bride marries the elder and as they leave the church, the horse acts up?  New hubby gets off horse and hits him upside the head with fist….  THATS ONE, he says.  They get a few miles…..then the horse really acts up.  New elder hubby stops, finds a limb, akin in shape to a Louisville Slugger.  Takes a mighty Babe Ruth swing and almost knocks out the horse…..THATS TWO, he says…..

Finally, they get to his house and the horse rears up.  He gets out.  BOOM from his Colt 45.  THATS THREE he calmly says.  He goes back to the buggy…his young wife is screaming and shouting and calling him names.  He calmly picks her up, lifts her off the buggy, holds his hand over her mouth until she calms down and shuts up.  He says…THATS ONE!

Post has been edited…..THATS ONE!!!!!

End of EDIT….

Getting back on track . . . .

My last 2 fillups this last weekend were 11.8 and 7.3 mpg.  Must be the tires?

Nope, the coach was level with the 11.8 and fuel was pretty level in the tank, not how I fill a tank.  On the return trip I jacked up the left slightly and got the extra gallons in, but at 7.3 mpg.  Total the two trips (893 miles / 104 gallons) and came out to my trusty 8.5 mpg.

So I guess it wasn't the tires after all . . . .

The second fillup was 75 gallons (100 gal tank) and the gauge showed half full.  I learned that painful lesson a long time ago. 

- bob

 

Edited October 17, 2023 by Tom Cherry
Politics or Political statements not allowed

[96 EVO]

Speed you fill the top of the tank can make a big difference as well.

Was in a hurry at a busy truck stop once, and ended up with about 7/8 tank when I got on the road.

Must have had 3 or 4" of foam on top of the liquid!

[Frank McElroy]

Although this doesn't apply in the case of the OP, when the new ISL 425 engines with DPF first came out in the 2008 model year coaches, the engine computer calculated and the Aladdin displayed fuel economy in the mid to high 9 MPG range.  Folks thought this was great.  I knew something was wrong because my actual fuel economy was in the high 7 to low 8 MPG range.

Sure enough, Cummins corrected the error a few years later in one of their software reflash updates.  After that happened the internet blew up telling folks not to get the software update because it lowered engine fuel economy.  Those were the folks that believed the Aladdin numbers and never did their own calculations based on tank fills and making corrections for generator and aquahot use hours.

So, how did Cummins get the wrong MPG calculation?  As it turns out for this ISL engine, on each power stroke there are 3 separate fuel injections timed to specific crankshaft positions and engine load.  Also, if in a regen cycle, there is a 4th injection near the end of the power stroke if more fuel needs to raise the temperature of the DPF. (The ISX uses a separate dosing injector on the exhaust manifold - The ISL doesn't have a separate dosing injector).  So, what happened is that Cummins basically forgot to include one of the 3 main fuel injections as part of the MPG calculation thus causing MPG to display on the Aladdin about 20% too high.

An interesting story that I thought folks would like to know about. 

[96 EVO]

Frank, do you think the '07 400hp ISL would be included in that group?

My Aladdin shows lifetime average of 7.6 MPG.

On longer trips with plenty of flat ground, my trip meter shows 7.9-8.0MPG.

The fuel remaining lines up pretty well with my fill ups!

Don't believe the ECM has ever been updated .

[Frank McElroy]

1 minute ago, 96 EVO said:

Frank, do you think the '07 400hp ISL would be included in that group?

My Aladdin shows lifetime average of 7.6 MPG.

On longer trips with plenty of flat ground, my trip meter shows 7.9-8.0MPG.

The fuel remaining lines up pretty well with my fill ups!

Don't believe the ECM has ever been updated .

The 400HP ISL didn't have that issue.  When you say that the ECM has never been updated, if you or any previous owner ever brought the coach to a Cummins shop, the ECM software most likely would have been reflashed with the latest software.  One way to know is to get a copy of the ECM report via Insite.  I could then tell you what software revision is on your ECM and if it is the latest one.  After about 10 years, Cummins stops issuing new updates because most all issues have been resolved.

[96 EVO]

I've never brought it in to a Cummins shop, but, the coach was about 5yrs old when I bought it.

I'll look into the Insite!

[Frank McElroy]

11 minutes ago, 96 EVO said:

I've never brought it in to a Cummins shop, but, the coach was about 5yrs old when I bought it.

I'll look into the Insite!

Offline if you send me your engine S/N, ECM Product ID (something like CM850) and the ECM code from the engine data plate, I can look up and send you a list of all available engine updates, when they were issued and major items they fixed.

[Tom Cherry]

3 hours ago, Frank McElroy said:

Although this doesn't apply in the case of the OP, when the new ISL 425 engines with DPF first came out in the 2008 model year coaches, the engine computer calculated and the Aladdin displayed fuel economy in the mid to high 9 MPG range.  Folks thought this was great.  I knew something was wrong because my actual fuel economy was in the high 7 to low 8 MPG range.

Sure enough, Cummins corrected the error a few years later in one of their software reflash updates.  After that happened the internet blew up telling folks not to get the software update because it lowered engine fuel economy.  Those were the folks that believed the Aladdin numbers and never did their own calculations based on tank fills and making corrections for generator and aquahot use hours.

So, how did Cummins get the wrong MPG calculation?  As it turns out for this ISL engine, on each power stroke there are 3 separate fuel injections timed to specific crankshaft positions and engine load.  Also, if in a regen cycle, there is a 4th injection near the end of the power stroke if more fuel needs to raise the temperature of the DPF. (The ISX uses a separate dosing injector on the exhaust manifold - The ISL doesn't have a separate dosing injector).  So, what happened is that Cummins basically forgot to include one of the 3 main fuel injections as part of the MPG calculation thus causing MPG to display on the Aladdin about 20% too high.

An interesting story that I thought folks would like to know about. 

AMEN.  I contacted Cummins after making the “commitment” or actually during my decision as there was a “custom” Scepter with a Dynasty ISL425 Mill….  And I had a verbal on the Camelot. I had the build sheet on each and VIN and Engine SN.  Cummins tech support advised….get an oil change from a Cummins dealer and get this (Revision) to the ECM.  Was FREE.  I stipulated that to the dealer….of course he did it….and I did require an invoice at delivery.  That was the one that Frank called out.  There were “HOWLS” about going back and making Cummins “roll back” the revisions because this blankety blank revision killed their mileage.  Some folks don’t understand keeping fuel records and recording mileage….Excel handles that. I became email and later phone friends with Frank.  He had more columns in his “fuel log” than mine….OMG….this guy is a genius.  LOL…seriously, the update just corrected a logic error….  Cummins billed it, IIRC, a major drivability issue….right…as in fixing the ECM….

[dl_racing427]

Wow, that's one revision that I'd think Cummins would want to thoroughly educate owners about, before getting them all in a panic. 😱

This reminds me of when Cadillac came out with the digital dash.
They had a fuel gauge display that read in gallons.
It was something like a 20 gallon tank, and the display would say F-19-18-17, etc. on down to the low fuel warning.
People complained that their old cars gauge would stay on F for 75 to 100 miles, while their new car started dropping after only 20 miles or so.
Basically, the fuel gauge was too accurate for the average idiot. 🤣
GM's fix was to reflash the dash so the gauge read F-17-16-15....  SMH  The idiots were happy though.

Ford had a similar issue back when they started putting oil pressure gauges in place of lights.
Drivers would complain on a hot day that their oil pressure dropped at idle.   Well, yeah, that's normal.
Instead of trying to explain that, Ford changed their gauges to have only two positions, normal and ZERO.
Now, instead of having an actual useful gauge, it tells you that your engine just seized.
It's actually WORSE than the idiot light.  At least the red light got your attention.

It's a d*** shame that the whole world has to cater to the dumbest 20% of the population. 🤬

[96 EVO]

It IS nice when you drive several miles before your needle drops to full!

Makes you feel like you had some free fuel 🤣!!

[dl_racing427]

1 hour ago, 96 EVO said:

It IS nice when you drive several miles before your needle drops to full!

Makes you feel like you had some free fuel 🤣!!

So you're the guy who barely puts enough fuel in your rental car to show F before turning it in.  🤣😉

[96 EVO]

13 minutes ago, dl_racing427 said:

So you're the guy who barely puts enough fuel in your rental car to show F before turning it in.  🤣😉

Yeah, but I do feel bad for the car waiting behind me at the pump, while I make several trips to check the gauge on the dash 😁!

Seriously.... I've never rented a car in my life!

[saflyer]

On 10/17/2023 at 7:49 AM, Steven P said:

That happened to me once before.  I recall noting the fuel mileage loss. The diesel smell after refueling grabbed my attention and made me check the other door.  In my case, I had opened it to add a fuel additive and forgot to cap it.  Lesson learned. 

What is confusing is after one fill a few miles down the road there was fuel all over my toad’s right side but that didn’t happen after the first refuel. For that matter the first time I actually overfilled to the point of getting some on the ground. But none on the toad after a long drive. Like I have said there are a lot of confounding points in this issue. My trip to Texas in February should give a lot better data.

[Tom Cherry]

9 hours ago, dl_racing427 said:

So you're the guy who barely puts enough fuel in your rental car to show F before turning it in.  🤣😉

DIVERSION WARNING....

Used to travel extensively.  Flew out of some smaller airports in Pennsylvania a lot.  Then started to drive back to Baltimore.  REASON.  Most of my Friday flights were mid afternoon.  In the smaller airports (say Harrisburg), there were many smaller convenience stores near the airport.  BUT, on Friday afternoon....the lines INSIDE were backed up....10 plus deep.  Folks buying their lottery tickets.  I finally DROVE OFF after throwing a $20 bill down and said....KEEP THE CHANGE...almost missed my flight...

YES....when you are trying to get fuel and make your flight...  

SERIOUSLY.....BUT, if one does, as most of the "Seasoned Citizens" member do here, one pulls up a Satellite view of the fuel stop....then decides.  I have been "burned" too many times by using the CHEAPEST place.  Once, I THINK, I cut a tire down as I ran over a curb....so all my "Savings" went up in smoke.  

NOTE...it does NOT take a high speed HIT THE CURB to cut a chunk out or make a ding.  Many of the folks on the old site would use common sense....Gas Buddy and Google Earth....and plan their fuel stops.  I do that without even thinking now, but I am more prone to using easy in and easy out level truck stops than fighting the obstacles to save a few pennies and I worry LESS about fuel contamination.....

2 minutes ago, saflyer said:

What is confusing is after one fill a few miles down the road there was fuel all over my toad’s right side but that didn’t happen after the first refuel. For that matter the first time I actually overfilled to the point of getting some on the ground. But none on the toad after a long drive. Like I have said there are a lot of confounding points in this issue. My trip to Texas in February should give a lot better data.

Not that I have done that....more than once.  It is to me, simple physics.  If you overfilled by tilting and DID NOT measure the angle that the MH was at.....you put in varying amounts of fuel....in that when level, one time the fuel level was really full and the fuel was higher up or you had more fuel in the filler spout.  The next time....not quite as much fuel....so it was lower.

The higher the level, then as you go into a gradual curve...with the open filler spout on the outside, the more centrifugal force....and the greater the odds of sucking or it expelling.  ALSO....if you drove on a level road for many miles, then the fuel level would drop.  

Bottom line.....either have a check list and follow it closely....or don't tilt.  All of this is random.  I would not try to analyze events or come up with crazy cause and effect scenarios when the parameters are totally different and the "design of experiments" ....what we engineers call the SCIENTIFIC APPROACH do not prevail.  Thus, it is all a matter of chance and the only known variable is the MH.  The amount of fuel that you "over added", the angle of the tilt, the final "level" of the fuel, the speed that you drove at, the crown of the roads, the number of gradual vs sharper (smaller radius curves, etc....are mindboggling.

At LEAST you figured it out.  NOW, if you did it big time, one would be using Simple Green to clean the inside of the fuel bay door, the chassis....  or maybe the Toad.

 

[Steven P]

1 hour ago, saflyer said:

What is confusing is after one fill a few miles down the road there was fuel all over my toad’s right side but that didn’t happen after the first refuel. For that matter the first time I actually overfilled to the point of getting some on the ground. But none on the toad after a long drive. Like I have said there are a lot of confounding points in this issue. My trip to Texas in February should give a lot better data.

I'd bet you may have made a lot more left turns on that trip or left curves causing fuel to move to the passenger side and slosh out easier.  Maybe other trips were straighter or more right curves?  Who knows?

[jacwjames]

When we bought our coach in 2008 I had no idea on fuel mileage.  I did rely on the fuel gauge a little but kept a log of miles and gallons.  Over time I had a pretty good idea of my fuel mileage.  A good test came in 2009, I got laid off from my job and we decided to take a trip to Alaska.  +14K miles later the log said  8.38 mpg including generator usage, not bad BUT we didn't pull a toad.

So if you really want to know what your real fuel mileage is keep a detailed log for 10K miles. 

In my case I just want to know how much fuel I have left in my tank and "Miles to Empty" which I get off my Silverleaf display.  If I really start thinking about fuel mileage I wouldn't take any trips. 

[Larry Laursen]

Fuel milage variation is very real from full tank to tank.  This because the tank runs across the width of the coach.  A one-to-two-inch difference in the left to right side of the coach while fueling will give about 5 gallons difference.  If you are only filing about 30 gallons this is significant.  I have tracked my fuel usage for 140,000 miles and the tank-to-tank fill varies from 5 to 12 mpg.  The 10-fill average is 7.5 to 8.5 mpg.  Total lifelong is average is 7.8.