Cylinder deactivation technology. It's out there on some vehicle. Why not more? Why not on the heavy duty Ford trucks specifically? I've noticed the #1 talked about topic in here is fuel mileage. It's my #1 concern and the reason I got the diesel instead of the gas engine.

I understand these are built to tow, but let's be honest, a large percentage spend a great amount of time driving around with nothing hooked up to them.

Mine is a '14 so I "only" have 800tq. Before getting it, I was pulling roughly 7500 pounds around with my V10 rated at 450tq with relative ease. So I'd like to think that my new diesel could manage getting itself around on half of it's cylinders and half of it's torque/hp. I wouldn't expect a 50% mpg improvement, but even if it was 20% that would be a huge savings.

My truck is not a daily driver. It was purchased for taking trips, with or without the travel trailer behind it. It sure would be nice on those trips without the rv if we could get 25+ mpg.

So, why can't/don't/won't they do this?

Just something that's been bugging me since getting the truck. We've taken three trips in it so far, one with the rv and two without. When we aren't pulling anything the truck accelerates so effortlessly I know it could cruise down the highway with half of the engine asleep.

Any geniuses on here have a good guess for me?


Ken

 

I have two buddies, both had a GM product, one a Suburban, the other a Yukon. Both have the variable displacement. Both have had problems, both no longer own them. One of them the engine was so gunked up with sludge it had to be rebuilt.

If you want good mileage, buy a VW Jetta TDI. If you want to haul stuff, keep your Superduty.

 

I am not aware of any diesel which utilizes cylinder deactivation technology. I suspect this is because
1. diesels are compression ignition and do not need to run a stoichiometric fuel ratio. Therefore if you only need to develop 60 hp to run at cruise down the highway it doesn't make any difference whether you squirt 60 hp worth of fuel into 8 cylinders or 4 cylinders.
2. No throttle on a diesel so less pumping losses. Not sure but I suspect that there may be some way to reduce the pumping losses on a gas engine in the deactivated cylinders
If this doesn't make sense it is probably because I have never really thought about it before, need to do some research on this technology
Feel free to educate me!

 

I'm just waiting for them to mandate the engine stop on medium duty truck market, and watch people start having all kinds of problems.

 

Your buddys' problem was that they owned a GM product. (ha...ha)

A Jetta isn't going to tow my travel trailer, unless Jettas have changed drastically from what I remember them being.

I need my truck to take trips, sometimes towing the rv, and sometimes not. It would be nice if it got GREAT fuel mileage when not towing the rv.

It was just a thought, and I wondered if maybe it was physically impossible with a diesel engine for some reason, or maybe they just don't feel like investing the time and money into developing it, or maybe Big Oil is slinding some money under the table to encourage them not to do it. Who knows? I don't.

 

That is the biggest reason right there.

 

get a retrofit for a cummins they only have 6 cylinders my grandpas chevy has the variable cylinders with 28k on it. he's 85 so he drives like that old person you hate to get stuck behind on the road and he gets the same milage as the f150 ecoboost i recently got ride of since it was a lease i drove it like i stole it

 

I just shed an 07 Chevy with that crap, scored 1 & 8 cylinders, went from a quart of oil ever 1000 miles to every 500. 100k and the motor was ready for a rebuild. If Ford put it in a desiel I'm out.

 

I've driven a 300C with the Hemi with MDS. Doesn't seem to do any good IMO. Can't really break 20 mpg on the highway.

 

In the same vein, as it were, why can't we buy an SD with 250hp/450 torque?

I'd be happy towing all my work and play trailers around if I gained 10% fuel economy by virtue of lower power. I mean really, I love yanking 12,000lb trailer up interstate on-ramps and passing cars before I have to merge, but I don't need to, lol.

Some of us drive in excess of 5,000 miles/month and even a 5% gain in economy is hard money very quickly.

I love the power but if I could flip a switch and get a de tuned motor for running long hauls, it'd be great and I'm sure make the EPA happy.

 

Guys, your trucks are already equipped with a variable power output switch. It's located on the floor, a couple inches to the right of your brake pedal. Learn to use that one gently and you'll get dramatically better mileage.

 

What fun is that??????

 

I had an 07 Avalanche with 5.3 AFM engine, around 185k km the AFM started acting up and was diluting the oil with fuel so I disabled it. My son had an 08 Sierra that he bought cheap with bad AFM lifters so he replaced the lifters, cam and cam drive to disable AFM. They need to have very good oil and oil change intervals, also a mod from GM to correct issues with it that requires dropping the pan and changing a rocker cover. Saves some fuel when it works but only on the highway.

 

My wife's Hemi Magnum used to get better mileage when it was younger, at 200k km area the MDS doesn't seem to help much, right now it's inactive as I have a failed oil sensor again and MDS quits when the CEL is on.

 

Since other vehicles were doing it, I was under the impression it helped fuel mileage. After reading posts here, I guess it doesn't. Should've looked into it more I guess before asking.

That would be very nice to have. I guess cutting half the cylinders off doesn't work or help, it would be nice to have something else that did like you said.

I'm well aware of this. After 5 years with a V10 gasser I'm probably one of the best out there at attempting to squeeze every mpg I can out of my truck.