F-150 towing a Hybrid 23SS - something is wrong...

[Stygshore]

Picked up a Shamrock 23SS a few weeks back, we have been getting it tweaked and setup for creature comforts in the drive. Had to bring it back up to the dealer the other day to get a leak in the bunk ends fixed.

Our first trip home with it we didn't pay a whole ton of attention to mileage or whatnot, it seemed to roll along well and we were happy to have a New to us camper.

This trip we filled up and paid attention. in 100 miles round trip the F150 ate up nearly 1/2 a tank of gas! That's going to make for some long expensive trips having to fill up every 200 miles.

Trailer is 23 ft long tongue to back - Tandem Axle - Shamorck 23SS Hybrid 4432 dry GVWR 6278

Truckis 2006 F-150 XLT SCrew with factory tow package including heavy duty hitch, larger trans cooler, and air assist bladders with 5100 adjustable Bilstein shocks.

Now where I think my issue may be... The truck has always seemed to have sort of a trans shutter on long slow slopes. When I got it from the dealer it had big 33" tires on it - but I am not sure they ever adjusted the speedo to the tire size, which seems to me would also mess up shifting?

I am working on 3 different ideas...

1 - Install a Chip Tuner to adjust performance for towing and adjust systems to the larger tires

2 - Put new tires on that are factory sized ( 30" as opposed to current 33"s )

3 - Switching from the factory 3:55 to a 4:10 rear differential or maybe larger to specifically setup for towing

I am not sure what will/will not work, and my options get exponentially more expensive as I go down the list.

Any help from the folks that have done this all before on what I can do to get this truck set up for towing would be awesome!

[Mr Havercamp]

Originally Posted by Stygshore

Picked up a Shamrock 23SS a few weeks back, we have been getting it tweaked and setup for creature comforts in the drive. Had to bring it back up to the dealer the other day to get a leak in the bunk ends fixed.

Our first trip home with it we didn't pay a whole ton of attention to mileage or whatnot, it seemed to roll along well and we were happy to have a New to us camper.

This trip we filled up and paid attention. in 100 miles round trip the F150 ate up nearly 1/2 a tank of gas! That's going to make for some long expensive trips having to fill up every 200 miles.

Trailer is 23 ft long tongue to back - Tandem Axle - Shamorck 23SS Hybrid 4432 dry GVWR 6278

Truckis 2006 F-150 XLT SCrew with factory tow package including heavy duty hitch, larger trans cooler, and air assist bladders with 5100 adjustable Bilstein shocks.

Now where I think my issue may be... The truck has always seemed to have sort of a trans shutter on long slow slopes. When I got it from the dealer it had big 33" tires on it - but I am not sure they ever adjusted the speedo to the tire size, which seems to me would also mess up shifting?

I am working on 3 different ideas...

1 - Install a Chip Tuner to adjust performance for towing and adjust systems to the larger tires

2 - Put new tires on that are factory sized ( 30" as opposed to current 33"s )

3 - Switching from the factory 3:55 to a 4:10 rear differential or maybe larger to specifically setup for towing

I am not sure what will/will not work, and my options get exponentially more expensive as I go down the list.

Any help from the folks that have done this all before on what I can do to get this truck set up for towing would be awesome!

Any benefits you'll gain from any of those ideas will be so small you'll not notice anything. Save the money you would spend on those for gas. You're towing a wall through the air. The best thing to get max mileage is slow down. The sweet spot will be somewhere around 60-65MPH. As you go faster the mileage will drop almost exponentially. Welcome to full height trailers. You could always get a diesel but you have to tow a ton of miles to offset the initial cost and it sounds like your occasionally camping and not full timing.

[rockfordroo]

Most folks with gasser 1/2 tons seem to get 9-11 mpg while towing. So assuming your gas tank is around 20 gals, you're doing about what everyone else is getting. You're pulling a giant sail down the highway.

With respect to tires: Check the outside diameter of your 33" tires. You may find it's the same as the 30" tires you want to put, it's just the wheel that's bigger. (My Traverse is this way - comes with 18" or 20" tires, but the OD of both is the same.)

Unless you do a lot of towing, the options you're looking at may not be cost-effective.

[kevinstennes]

I have a 2012 and a 2015 F150, both with 5.0 V8, 4x4, Screw, 3.55 rears. Haven't towed with the 2015 yet, but plan to do so next month on a 2,000 mile trip. Towing my 27' TT with the 2012 yields between 8.8 and 9.8 MPG, at the very best. We'll see how the 2015 does with the trailer, as it certainly gets better mileage than the 2012, when not towing.

I'm not sure anything is wrong with your truck. I have 35 gal tanks on my trucks and the needle moves pretty fast.

[KMP44]

Originally Posted by Stygshore

Now where I think my issue may be... The truck has always seemed to have sort of a trans shutter on long slow slopes. When I got it from the dealer it had big 33" tires on it - but I am not sure they ever adjusted the speedo to the tire size, which seems to me would also mess up shifting?

I am working on 3 different ideas...

1 - Install a Chip Tuner to adjust performance for towing and adjust systems to the larger tires

2 - Put new tires on that are factory sized ( 30" as opposed to current 33"s )

3 - Switching from the factory 3:55 to a 4:10 rear differential or maybe larger to specifically setup for towing

I have a similar truck/trailer combo. I'm assuming you have the 5.4 liter? Gas mileage is a lost cause when you are towing a big square box behind you. Our first long trip with the Roo 3 years ago was 2800 miles with near $4 a gallon gas. Would have been cheaper to fly! But that wasn't really the point of the trip... Anyhow 7.5 mpg towing the Roo has been common for us even though I never tow over 65mph.

Not sure what exactly you mean about the tranny issue. With this engine (and most other gassers) you need fairly high rpms to get the max torque, so on the hills it revs pretty high (and kills you mpg). Mine sometimes hunts a little on hills as it downshifts but doesn't like to stay in the lower gears. Locking out the O/D doesn't really do anything for that issue.

A tuner might help you change shift points if that's the main issue. Going back to factory size tires might also help - but if you don't need new tires that's kind of an expensive guess. I definitely wouldn't invest the money in changing the gear ratio.

Before spending any real money though, I would try just letting it run at higher rpms on the hill. Sounds a little un-nerving, but my gage red lines at like 8,000 and I've found 3500 to maybe 4000 rpms on the hills keeps it from constantly up shifting/downshifting.

Congrats on the new Roo, btw.

[robsshots]

Amazing. I tow a fifth wheel 8280WS with my F150 and a 3.73 rear end ecoboost. Getting 10.5 mpg keeping it at 60 - 62 mph. That's my average with a 2014 truck and towing about 8,000 miles.

[stantyszka]

How large is your gas tank? You should figure roughly 10.5 to 11 mpg. If your tank is 22-24 gallons that's about normal consumption.

[ccsvolsfan]

That's why I traded the f150 for a low milage f350. Of course that led to buying a fiver. The f150 5.4 just isn't a great truck for the trailer you are pulling. Hill country will take a heavy toll.

[Stygshore]

I calculated roughly 5 MPG on this trip to and from the dealer - I run around town at about 12-13 in the limited driving I currently do in the truck ( work from home, drive wife's car as a family 90% of the time )

Currently at 65 mph the RPMs level out and aren't constantly shifting up and down and we are running about 3300 RPMs on the flats <- This seems high to me for a truck that runs 1800-2000 without towing and about 2200 towing a 12' box Coachman Pop-up camper( 3200 loaded ) prior to the Shamrock.

My tires themselves are 3" bigger than the stock tires 285 vs 255 70/r17s.

The dealer said the adjustment to tire size to speedo probably wont do much, but putting the factory tires back on or changing the rear differential will help a lot ( he was happy to sell me new tires or another truck if I wanted one as well )

Tuner shop said that tire size adjustment and tuning to tow may fix the stuttering and up/shift downshift on long slopes, and may keep it in a set gear more efficiently, but admitted if you are buying a tuner for better gas mileage, you would be better off just putting that money into your gas tank.

Kind of at a loss and starting to shop F250's locally in case I can get a $30 more a month car payment to save $100.00 a month in gas. ( we have at least 1 long or 2 short trips booked for the remainder of camping weather this year )

Styg

[Stygshore]

Originally Posted by ccsvolsfan

That's why I traded the f150 for a low mileage f350. Of course that led to buying a fiver. The f150 5.4 just isn't a great truck for the trailer you are pulling. Hill country will take a heavy toll.

In-laws live in Rapid City SD in the Black Hills... already nixed the idea of dragging the trailer out that direction. I remember an overloaded trip with a U-haul back to Michigan getting about 4mpg in the hills with only a 19' box.


Styg

[rsdata]

9-10MPG is great... I get about 7, but I have the 35 gal tank size and a small 5.2 liter engine...
go to local tire dealer (IF you need tires anyway) and find out what stock size tire is AND circumference of that tire. Smaller tires will be like upping the rear gear ratio which might be a good thing as 3.73, 4.10 and up are considered towing ratios, not 3.55.

I find I get better fuel economy with OD off... I used to manually cycle it on/off depending on terrain, but find it easier to leave it off and I get about 1/2 gal better fuel economy that way.

When you figure the current and projected price of gas... the extra $$$ you put in the tank won't be nearly as mcu as a bigger car payment.

Easy check on speedo accuracy is to drive at 60 MPH and click off 1 mile on interstate mileage markers... 1 mile should take 60 seconds.

[ilovecamping]

We tow the same trailer with a 1500 Suburban and that is probably about the mileage we get. We are planning a long trip this summer and what we save by camping vs hotels and eating in vs eating out will more than make up for the gas we spend. Even if it didn't we would still camp because that is what we enjoy. Take a deep breath and just enjoy it all. Good luck!

[Stygshore]

Originally Posted by stantyszka

How large is your gas tank? You should figure roughly 10.5 to 11 mpg. If your tank is 22-24 gallons that's about normal consumption.

My tank is 26 gallons so maybe 7.5 mpg is the best the 5.4 can do towing. Previous owner had it all decked out for towing when I bought it - maybe that's why he got rid of it - just couldn't do better no matter what he threw at it


Styg

[Stygshore]

Originally Posted by rsdata

9-10MPG is great... I get about 7, but I have the 35 gal tank size and a small 5.2 liter engine...
go to local tire dealer (IF you need tires anyway) and find out what stock size tire is AND circumference of that tire. Smaller tires will be like upping the rear gear ratio which might be a good thing as 3.73, 4.10 and up are considered towing ratios, not 3.55.

I find I get better fuel economy with OD off... I used to manually cycle it on/off depending on terrain, but find it easier to leave it off and I get about 1/2 gal better fuel economy that way.

When you figure the current and projected price of gas... the extra $$$ you put in the tank won't be nearly as mcu as a bigger car payment.

Easy check on speedo accuracy is to drive at 60 MPH and click off 1 mile on interstate mileage markers... 1 mile should take 60 seconds.

Speedo doesn't match the TomTom, so we know it is off, and also doesn't match the GPS app I put on my phone. I did verify stock tire based on VIN, and spoke to dealer and tire shop ( dealer told me they will beat any tire shop pricing by 1.00 )

The wife and I were trying to decide if the rule about O/D off when towing still applied with modern vehicles.

Styg

[RussPastuch]

Yep, on a good day I get 11.5 mpg pulling a 26 footer.

[mike.t]

Originally Posted by ccsvolsfan

That's why I traded the f150 for a low milage f350. Of course that led to buying a fiver. The f150 5.4 just isn't a great truck for the trailer you are pulling. Hill country will take a heavy toll.

I had an F-250 5.4 with tow package and it was the worst TV I have ever been in. Crapping mileage(tow and no tow) and no towing umph.

[Kaadk]

Hmm, if it has the factory tow package, does it also have a button for a tow mode? Might not need a different tune chip if it's already built into your truck.

But, for reference, my 1500 only gets about 9 mpg when towing, (17 otherwise as I do mostly highway between work and home). But if I forget to turn on the tow mode, that 9 mpg usually ends up closer to 8 mpg.

In the long run though, 8 vs 9 mpg isn't much of a difference compared to the 48 mpg I used to get with my old Saturn. But I couldn't sleep 6, cook meals and shower in a Saturn, so this is the trade off.


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[mike.t]

"In the long run though, 8 vs 9 mpg isn't much of a difference compared to the 48 mpg I used to get with my old Saturn. But I couldn't sleep 6, cook meals and shower in a Saturn, so this is the trade off".

Well said.

[ablindmule]

I have just about the same set up, and as others have mentioned, probably best just spending the money on gas and keeping the speed around 65 mph. Going 70+ really cranks up rpms and really decreases the mpg. Hills definitely kill the mpg. I live in central Virginia, heading towards the beaches, most of the trip being very flat, I can actually set the cruise control and have gotten 11 mpg towing my Roo. Heading west towards the mountains, or Southwest to one of the lakes we camp, being very hilly, mpg drops to eight or nine, plus I have a lot more control on shifting if I simply don't use cruise control when hilly.
Good luck! Congratulations on the new Roo, you will love it.

[KMP44]

Originally Posted by Stygshore

Currently at 65 mph the RPMs level out and aren't constantly shifting up and down and we are running about 3300 RPMs on the flats <- This seems high to me for a truck that runs 1800-2000 without towing and about 2200 towing a 12' box Coachman Pop-up camper( 3200 loaded ) prior to the Shamrock.

My tires themselves are 3" bigger than the stock tires 285 vs 255 70/r17s.

The dealer said the adjustment to tire size to speedo probably wont do much, but putting the factory tires back on or changing the rear differential will help a lot ( he was happy to sell me new tires or another truck if I wanted one as well )

3300 rpms on flat ground does seem high - and explains your drop in mileage. We pulled our 2800 pound popup for a year with the F-150 before getting the Roo. Night and day difference because of the giant square front on the Roo. The shape / size is more of an issue than the increased weight your pulling.

I think that the current tire size may be the biggest issue. And are you sure its a 3.55 ratio? I thought any f-150 with the factory tow package got the 3.73. But going smaller on the tire size will effectively increase your gear ratio. I can tow 65 on flat ground at 2200-2300 and get 8mpg or so.

I don't think you'll ever get this combo to 10mpg, but seems like maybe the prior owners mods might be part of the issue.

And my next truck will have at least a 34 gallon tank for sure. Glad to see Ford is offering bigger tanks on all the new trucks. 2017 F-250 cc long bed has a 48 gallon tank. That would fix the stop every 2 hours problem! Of course then we would need a new thread to complain about the cost of fill-up.