Force Truck to Run in 4 Cylinder Mode

[kalapakim]

I just bought my 2021 Ram 1500 Big Horn and I'm interested to know how to run on 4 cylinders all the time, to save on gas, and how to change it back to 8 when I want the power. Any assistance would be appreciated.

Thank You!

 

[Drewster]

Just a heads up, you're going to be in the minority. Your best option is going to be managing your right foot, but you might also reach out to Range Technology - their product was actually designed to use MDS more often to make the vehicle more efficient, but it turned out most folks just wanted MDS off all the time, so that's most of what they sell now. I don't think they have anything for DT vehicles, but they'd probably like to hear someone who wants more MDS

AFM+

Range AFM Plus optimizes your performance by better identifying your driving situations helping you get more miles out of a gallon of gas.

www.rangetechnology.com

 

[Richard320]

It will never run on 4 all the time. You'd be accelerating from stops like one of those 1980s Toyota motorhomes. To get the most MDS, a light foot is what it takes.

And be sure you have turned on the ECO light in the uConnect settings so you know when it's active.

 

[silver billet]

You can have my MDS, that way you have two 4 bangers and then ... wait.

Just razzing you. There is no way to force it on, these trucks can barely hold speed on a flat road with MDS active.

 

[User_3336]

I just bought my 2021 Ram 1500 Big Horn and I'm interested to know how to run on 4 cylinders all the time, to save on gas, and how to change it back to 8 when I want the power. Any assistance would be appreciated.

Thank You!

You're NOT serious are you????????????????????????????

 

[LouNY]

I would like to be able to control this function also,
keeping it on a bit more at times and off at times.

 

[jdmartin]

I don't know - doesn't really sound that useful to me. I can't imagine that 4 cylinders could pull this truck on anything more than total flat ground in good weather at low speeds. This is a pretty heavy vehicle. How much fuel could you possibly save? If one could save more than 2 MPG I'd be surprised, but even if you could save 5 MPG and could use it 50% of the time (I doubt it), here's how it would look over a year (let's say 1k miles per month):

12k miles @ 18 MPG average = 666 gallons
6k miles @23 MPG + 6k miles @18 MPG = 593 gallons
70 gallons per year @$3/gallon = $210 savings per year.

Maybe it's just me, but the added complexity to save $200 per year - and that's if you could use it 50% of the time, which I seriously doubt - doesn't sound financially worthwhile to me. And I can't think of any other reason you'd want to do this except save money, unless you're a super eco-activist that also believes in driving a big, thirsty full-size truck.

 

[Dusty1948]

I just bought my 2021 Ram 1500 Big Horn and I'm interested to know how to run on 4 cylinders all the time, to save on gas, and how to change it back to 8 when I want the power. Any assistance would be appreciated.

Thank You!

In reality you would more likely to suffer increased fuel consumption by constant four cylinder operation. Trying to move a 5000+ lb. vehicle with half the displacement of the 5.7 Hemi would likely mean you would be using excessive throttle pressures to accelerate and maintain speed.

The MDS system was not designed to be anything more than a supplemental fuel management approach under no-to-light load conditions.

Best regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 053848 miles.

 

[Drewster]

In reality you would more likely to suffer increased fuel consumption by constant four cylinder operation. Trying to move a 5000+ lb. vehicle with half the displacement of the 5.7 Hemi would likely mean you would be using excessive throttle pressures to accelerate and maintain speed.

The MDS system was not designed to be anything more than a supplemental fuel management approach under no-to-light load conditions.

Best regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 053848 miles.

This isn't actually true - when you switch to MDS, those 4 cylinders will run at higher load. That load transition is why there's a "bump" - you're switching from 8 cylinders putting along to 4 running almost as hard as they can

If you think about it, a V8 running at 30% load can't just switch 4 cylinders off without suddenly slowing down and the driver noticing. It has to change throttle position and run the four at 60+% load to make up for the dead cylinders. The magic here is that cylinders at high load have a lower Brake Specific Fuel Consumption (BSFC), so it's more efficient overall.

That being said, the ECU has loads of tables it uses to tell when it's optimal to engage MDS - BSFC is not linear. I'm sure it's not *entirely* optimized for fuel consumption since they know it creates NVH; it's probably true that placing efficiency over comfort would yield positive results at the pump... but there are other areas where all 8 cylinders probably have a better overall efficiency. I'm honestly not sure if you can even idle properly with MDS engaged, for example.

 

[Mountain Whiskey]

I'll let you in on a secret. Not many people know this, so keep it under your hat. Ram will sell you a truck that has only uses six cylinders at any time. That's right. It never jumps in and uses eight gas hogging cylinders.

 

[mmcbeat]

Dang, I wish I could “force“ my Ram to run on eight cylinders all the time,

 

[Trippi]

take the truck back if you're actually trying to save on gas. Although I was happy to see my Rebel hit 18.3 today with proper foot management and cruise control on the thruway.

 

[Trooper4]

Dang, I wish I could “force“ my Ram to run on eight cylinders all the time,

Turn off MDS?

 

[Rlaf75]

My 2011 bighorn seemed to enter "eco" mode a lot easier than my new 21 does. I could actually feel the difference in the 11 compared to the 21.

 

[Scram1500]

This can't be a real question

 

[User_3336]

This can't be a real question

That's what I was going to say (but didn't). Almost like we're being trolled. BUT, it got people to responding.
Strange that would be a newb's first question on the day they signed up!

 

[Expat]

Dang, I wish I could “force“ my Ram to run on eight cylinders all the time,

you can...............

 

[Buffchief52]

I just bought my 2021 Ram 1500 Big Horn and I'm interested to know how to run on 4 cylinders all the time, to save on gas, and how to change it back to 8 when I want the power. Any assistance would be appreciated.

Thank You!

Buy a 2021 Ford Ranger or 2020 Maverick. (4 cyl 4x4 Ranger gets same mileage as Ram 5.7 ETorque!!)

 

[millerbjm]

I find it strange how upset people get at the idea someone might want to run in 4 cylinders and be more efficient with their truck - will never understand why others seem defensive about it and feel the need to question the validity of the question. My 1st ram had the V6 and it was a great truck that did everything I needed and used less fuel doing it. My last 2 have been Hemi trucks because I couldn't have a CC and 6'4" bed with a V6 and that combo was important to me. I would love a truck that could run on fewer cylinders in daily driving and more when I want fast starts or heavy towing like to OP is thinking. My truck is in Eco mode at least 50% of the time in both city and highway driving so it seems to work well. In the end I think the V6 is the perfect mix of mpg and power for 99.9% of truck users who don't tow more 5,000lbs.

 

[Trooper4]

I find it strange how upset people get at the idea someone might want to run in 4 cylinders and be more efficient with their truck - will never understand why others seem defensive about it and feel the need to question the validity of the question. My 1st ram had the V6 and it was a great truck that did everything I needed and used less fuel doing it. My last 2 have been Hemi trucks because I couldn't have a CC and 6'4" bed with a V6 and that combo was important to me. I would love a truck that could run on fewer cylinders in daily driving and more when I want fast starts or heavy towing like to OP is thinking. My truck is in Eco mode at least 50% of the time in both city and highway driving so it seems to work well. In the end I think the V6 is the perfect mix of mpg and power for 99.9% of truck users who don't tow more 5,000lbs.

Guess it makes some people feel superior to step on others. There really is no "perfect", otherwise we would all be driving the same identical vehicle, living in the same identical house, and agree with everything that everyone thinks, says, or does. How boring. But, then again, some are just up for an argument no matter the situation.