Turning off MDS kills my gas mileage..

[BlownGP]

So I've been running with it out since I bought the truck two years ago.

Read all the threads about turning it off and how great it is.
Turn it of and really didn't notice much of a difference. Exhaust sounded the same and acceleration might have lagged a little less.

Ran it for two fill ups and got barley 12mpg. With it on I was get mid 14s.

So just my 2 cents..lol

 

[Hemi395]

Good info, so that's about a 15% drop. That definitely adds up over time.

Personally I like MDS. I try to get my truck into it as much as possible on every highway trip and my highway mileage is 20-21 usually and my truck is leveled.

 

[SlowRoller]

Yep. MDS is a proven fuel-saver. About the only folks that MDS won't help are those with a 400 lb right foot,,, =)

 

[dhay13]

i don't have official data but my mileage seems to be worse with MDS off too. but that may be that i only turn it off when i'm in town, which naturally will be worse mileage either way

 

[WadXpress]

I turned off mds a month ago. Driving in town I had lost some mpg. I thought the guys that said they gained mpg with it off I thought were nuts. Then I saw the gains

I did my drive from oregon to north dakota and gained 3 mpg for the drive. I had made the drive 4 or 5 times and the best I could do was 18.5 mpg on the evic. This last time with it off ot was 21.5 or maybe even a little better. I'm still getting 18-19 mpg to and from work out here but it's a straight shot no traffic lights or stop signs

 

[sicmadek]

I get great mpg and mds has been disabled for over a year now.

 

[DavidRam]

What's MDS??


Lol

 

[preachp]

Hi davidram,

MDS stands for multiple displacement system. It shuts unneeded cylinders off to save fuel.
Instead of firing all eight cylinders all the time it only uses four when the engine is not working hard.

preachp

 

[BlownGP]

Hi davidram,

MDS stands for multiple displacement system. It shuts unneeded cylinders off to save fuel.
Instead of firing all eight cylinders all the time it only uses four when the engine is not working hard.

preachp

I think he was being sarcastic. lol





Yeah, my fuel log app computes my gas mileage between tanks.

I did my normal driving to work and bs on the weekend like normal and MDS was worse.


BTW, this was on the canned 87 tune with 89 octane gas.

 

[Ramrt1]

Negative, I maintain 22-23mpg highway anytime I leave the stop and go traffic. Once I set the cruise to 65-70mph and stay off the gas my gas mileage doesn't suffer. My truck was rated at 15 city/ 20 hwy. 2012 R/T with 4.10 gears, flowmaster 50 series hd, stock intake with k&n drop in filter and throttle body, hemifever 93 octane hr custom tune. I deactivated traction control and mds so that's not your problem. I only use 93 octane fuel, and use seafoam in my oil and gas.

 

[MSExpress]

It is nice to turn off driving around town, but on the eway it's always on in my truck

 

[BlownGP]

Negative, I maintain 22-23mpg highway anytime I leave the stop and go traffic. Once I set the cruise to 65-70mph and stay off the gas my gas mileage doesn't suffer. My truck was rated at 15 city/ 20 hwy. 2012 R/T with 4.10 gears, flowmaster 50 series hd, stock intake with k&n drop in filter and throttle body, hemifever 93 octane hr custom tune. I deactivated traction control and mds so that's not your problem. I only use 93 octane fuel, and use seafoam in my oil and gas.

I never tired it on the highway..

But I dont see how you are getting 23 on the highway. Especially with not even having the 8 speed and you have 4.10s? ooooooooook.

 

[SlowRoller]

93 octane custom tune is why. Pull it back to 87 / OEM and try it again,,,

 

[sicmadek]

I never tired it on the highway..

But I dont see how you are getting 23 on the highway. Especially with not even having the 8 speed and you have 4.10s? ooooooooook.

I have 6 spd 3.92 qc and i get 22-23 mpg at 70 mph. I usually avg 16-17 mpg for the tank but i cant keep my foot out of it when off the hwy.

 

[jwheeler]

Why would anyone be surprised by lower fuel economy with mds off? Better mileage is kind of the entire idea behind the mds.


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[SlowRoller]

Why would anyone be surprised by lower fuel economy with mds off? Better mileage is kind of the entire idea behind the mds.

Stranger still, why would anyone argue they get BETTER mpg with it off?

 

[RLJ10X]

I always suspect that the guys getting 23 mpg, are resetting the evic once they are up to speed. Then they quote the evic reading. However, an evic reading of 23, is probably 20.5 or better in reality; Which is still impressive.

I also suspect the Tune helps.

RT is another example of 6/4.10 getting good fuel economy. The catch is: You have to put in a little effort to get good mpg.

I'll accept that the truck gets better mpg with the mds turned off, as soon as someone explains why.

 

[Rzrman328]

I turned mine off for 2 tanks and big surprise, I got worse gas mileage.

It's already bad to begin with(37's)...but it was slightly more horrific without it.

I think if you absolutely don't care about gas mileage then turn your mds off lol.

I don't need all 8 firing ALL the time.

I will admit, when it kicks on my exhaust note is not very pleasant but it's only For short intervals.

My mds will remain active lol.

 

[BlownGP]

93 octane custom tune is why. Pull it back to 87 / OEM and try it again,,,

If you're talking to me. I run the 87 canned tune.

I have 6 spd 3.92 qc and i get 22-23 mpg at 70 mph. I usually avg 16-17 mpg for the tank but i cant keep my foot out of it when off the hwy.

Must be nice.. hahahahaah

I did get 19ish on my road trip last month.

Why would anyone be surprised by lower fuel economy with mds off? Better mileage is kind of the entire idea behind the mds.


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I'm not, I was surprised when people said they get better MPG's with it off. So I decided to try it.

 

[jwheeler]

I'm not, I was surprised when people said they get better MPG's with it off. So I decided to try it.

Oh ok. Yeah, that is likely hog wash. I turned mine off after my header install because of the sound and lost 2mpg.


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