Engine Revving While Towing on Hills

[Astepatatime]

I have a new Ram 1500. It has the e-torque 5.7 and the 3.21 transmission. It's a limited, anniversary edition.

We are on an extended, 6,000 mile road trip. Left Texas yesterday. We are towing a Haulmark 7x14 Transport cargo trailer (dual axle). It's 2,110 lb dry. We have a 1,000 lb motorcycle in it, plus some luggage. Let's say 3,500 pounds. I figure payload (with 10% tongue weight) at less than 1,000 pounds, well under capacity.

I've been suprised how poor fuel mileage is. Cruising at about 65-70, most of the time the engine is around 2,000 RPM and I get 10-11mpg. Ok. I'll live with it.

My real concern is that any kind of hill (think rolling hills in KS) and/or a stiff headwind (it's gusty in north Texas) and the engine will rev up to 3,000 rpm or more. Sometimes just the slightest acceleration and the engine revs. Gas mileage then drops to 7 or 8. I can get it back down to 2k rpm by letting off gas, but then speed drops off course...to like 60.

I've got a lot of mountains ahead of me. A little worried about it handling it...or having to crawl up them.

Tomorrow I'll play with the manual shifting (ERS) and see how that works. But a question to the forum - is this "normal" transmission behavior? The revving up in RPM and big drop in gas mileage is a bit nerve wracking.

P.S. I'm coming from a F250 diesel so this it an all new animal to me. Thanks in advance.

 

[LaxDfns15]

The weight isn't really the issue with the truck. It's the ~50 square foot sail you're pulling at 70mph and expecting to go 70mph up hills. With the 3.21 gears you're also going to have to downshift (hence the 3k rpm's to maintain 70) to get enough torque.

Drive 55-60 and everything will be better. Comparing an F250 diesel to a 1500 3.21 gasser is apples to oranges.

P.S. Going 75mph up the Smokies pulling nothing I see 7-8 mpg with my 3.92 gears.

 

[Astepatatime]

Comparing an F250 diesel to a 1500 3.21 gasser is apples to oranges.

Wasn't comparing, I know it's different Just referencing what I am familiar with.

Yeah, I tried to keep it mostly at 65...sometimes 60-65. Hard to do 55-60 on TX roads with 75 or 80 limit...you become a safety hazard.

I'll try the downshift on the hills and see how that helps.

I've also been watching transmission temp. It seems to rev a lot more when the temp gets above 200F. Not as much below that. Interesting.

 

[Sascwatch]

Yep enclosed trailers are horrible for mileage loaded or unloaded. This is why I got the ecodiesel, it tows my 7x17 extra tall v-nose with ease in 7th gear all the time. I still only manage an average of 14-15mpg towing it tho.

 

[Dewey]

Sounds like 3.92’s would have worked better for you. Might even get better gas mileage in this case since the trans won’t be shifting up and down so much.

 

[JF19Longhorn]

Yeah, 100% normal.

I have a larger trailer (20' x 8.5' w/ 5.5' V-nose), but we're probably pushing close to the same frontal area. Empty towing I can see anywhere from 12.5mpg to 8mpg depending on the speed & grade of the roads. I leave T/H on and RPMs usually she sits just above 2k (3.92's) on level ground going hwy speeds, but will climb at the slightest hill, headwind, etc. She sat at 3,800 rpms for a solid 5 minutes climbing one hill heading to TN last year. Had more pedal to give and would have accelerated if I had asked.. but I felt bad and kept to the slow truck lane going around 60mph.

Temps were all normal while towing. (pic below)

 

[Rick3478]

At the end of the day, it's a truck engine.
It's designed to do this.
All day long.

 

[Scram1500]

The Hemi loves to rev, let it rip. Mine sees 5-6K rpms multiple times a week

 

[John Jensen]

I've been suprised how poor fuel mileage is. Cruising at about 65-70, most of the time the engine is around 2,000 RPM and I get 10-11mpg. Ok. I'll live with it.

My real concern is that any kind of hill (think rolling hills in KS) and/or a stiff headwind (it's gusty in north Texas) and the engine will rev up to 3,000 rpm or more. Sometimes just the slightest acceleration and the engine revs. Gas mileage then drops to 7 or 8. I can get it back down to 2k rpm by letting off gas, but then speed drops off course...to like 60.

Sounds normal to me for your load and how you are driving.

 

[Rebel2022]

As others have said, no worries with anything you said. I also came from a diesel (cummins) and it does take a little getting used to all the constant shifting and revving but the truck is built to do that. One thing I do though is limit the gears to 7 or 6 depending on the wind or hills. This leads to much less shifting.

 

[CalvinC]

It’s a naturally aspirated Gas V8, so it’s really not trying if it’s not screaming at least 3k rpm. Hemi has plenty of horses, but they live in the penthouse.

It would actually be bad for you to try to keep the revs down, such as manually shifting up (if it even allows it) or constantly backing out of the throttle when it downshifts. That is how you overheat.

Let it rev where it makes its power most efficiently, moves coolant through the engine at higher volumes, and keeps your transmission from being hyperactive about gear selection.

Diesel vs NA V8…. Welcome to a whole new world.

In short, let er eat.

 

[Astepatatime]

Thanks everyone.

Better day today...worked up thru western Nebraska and South Dakota. More rolling hills. Played with shift up/shift down.....but the computer often overrides it. Still, by being a bit more light footed on the up hills and getting it into 6th or 7th whenever I could, averaged a bit over 10mpg today while running around 65mph most of the time.

And good to know it likes the high RPMs.

 

[Bpebler]

I’m just assuming you’re probably also in Tow/Haul mode, right?

 

[Richard320]

I’m just assuming you’re probably also in Tow/Haul mode, right?

An excellent question. Tow/haul stops a lot of that gear hunting on uphills.

 

[bucolic]

Sounds like 3.92’s would have worked better for you. Might even get better gas mileage in this case since the trans won’t be shifting up and down so much.

3.92's won't make any difference at HGWY speeds. They help to get a heavier load going but at hgwy speeds zip nada no difference. I had both and towed the same trailer and no difference.

Traded for the Ecodiesel and it's a much more relaxing tow vehicle. The Hemi wants to rev and scream and the Ecodiesel just gets it done.

As others stated all is normal. Let it rev up and go all day long the Hemi loves it!!!

 

[fishslayer]

its fine.. You are puling a big parachute behind you.. think drag car at the end of 1/4 mile.. the HEMI needs to get a little rpm up to produce torque for hill climbing with loads.. its normal . you cant hurt it.. I regularly pulled 12,000 lb trailers with both of mine .. no issues .

 

[Bob.]

Also on the down hills (get a running start) pick up the speed a little more, it's easier to crest the next hill. Sure the motor has the ponies but the ponies will not be needed as much.

 

[c3k]

As others asked, the Tow/Haul mode is made for your scenario.

I don't know if all versions of this truck come with it.

 

[Astepatatime]

I’m just assuming you’re probably also in Tow/Haul mode, right?

Yep.

But of course there is the issue with the etorque engine and towing when it throws a U0402 code and then goes into limp mode and CEL goes on. It's happened twice on this trip (1800 miles so far).

Easy fix, stop, turn off, back on. But irritating. Various reported fixes included turning Auto Stop/Start off and or T/H on or off.

 

[usedup]

My '22 has 3.92's in it and on interstate with just a little grade I've seen 4500 rpm doing 75 in tow mode with the cruise on. The best thing to do if you need to go that fast is to pedal it on any slight grade. Takes gas to move stuff.