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Discussion Starter #1
I just pulled the trigger on a Diablo Sport controller and Hemifever custom tune. Hemifever wants to know if I want to disable the MDS. I've searched online but could mainly find debates on if MDS actually saves you gas or not. Are there any advantages or disadvantages to MDS such as throttle response time? If not then I'll probably keep MDS for highway cruising. Thanks in advance.
 

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I would disable the MDS. You're getting a "custom tune" for an 8 cylinder, so forget about the 4 banger mode.


I run my Scat Pack in "Sport Mode" all the time, and still get 25+ mpg on the highway/Interstates. On my previous '10, Sean did a custom tune for me, and I had the MDS disabled too.


IMO, the 1.5/2.0 mpg increase with MDS just isn't worth it. The engines just don't run as smooth on 4 cylinders, and there is a slight delay in throttle response.


Just not a fan of MDS anymore.
 

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Discussion Starter #3
Sounds reasonable. I'll have it disabled. I can always enable it via the controller if I really want to, I suppose. Thank you.
 

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If I could disable it without a tune I definitely would. I'm always in sport mode now because I find the MDS to restrict the car too much. I feel like I'm forcing the car to accelerate when it's active. As far as gas mileage goes, I'm hovering constantly around 13 whether I'm in default mode or sport.
 

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I would disable it also. One of my R/T's had an auto (MDS) and I currently have a Ram R/T. I noticed no difference in mileage at all with MDS on or off. I suspect MDS is just eyewash to placate the Feds. I'm sure in their fantasy test loop in the shop when they certify these things, there is a slight difference. But in the real world, nada. This is one reason I now have a Challenger SXT. I wanted the 8 speed but that MDS is just too damn annoying and I don't want to run in sport mode all the time. That DOES decrease mileage.
 

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I love the MDS with it I'm around 24 avg and babying it 25. Sport mode or stickshift 19-21. May not seem like much however that is 50+ mikes difference an extra day of gas
 

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Glad i read this, i might someday have to make this decision soon too.
I dont know if its placebo when it goes into 4cyl mode im thinking im saving gas.. but at the end of the day or week, from my driving and idling the mpg reading i cant trust because it factors in the car sitting idling.
When i get my tune i'll probably disable it, if i dont like it i can always turn it back on. I guess thats the good thing about having a choice to tunes to buy from.

The only real proof i have of 4cyl helping is the hwy mpg i topped out at 29mpg
 

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if possible, see if you can have two versions of tune:

-one with MDS enabled
-one w/o MDS

so that if you wanted to, you could load either tune depending on the situation (presuming you're using a hand-held device to load / unload tunes)

I see you have '17 which disables MDS with Sport Mode (unless a tune would over-ride that function)

If you're driving on the highway, MDS + 5.7 can get pretty good MPG with the A8...which is pretty remarkable that you can hit nearly 30 mpg.
 

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Discussion Starter #13 (Edited)
If I cared about my warranty I would have bought a Toyota or a v6 Challenger. The other option is to have a stock ECU. Then they'll never know.
 

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Discussion Starter #14
I've been wondering that that drone sound was for weeks. It sounds like lowend bass and I thought there was something wrong with the speakers. Turns out it's when the car actually goes into the MDS mode. I hate it. It sounds awful. I'll probably turn it off and have a second tune file with it on if I ever want it on but I can't imagine I would.
 

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If you disable MDS should you replace the lifters in the center 4 cylinders? Just asking. For everyone saying to use "Sport Mode" to disable it manually, that is not really the same as disabling MDS by itself. As Sport Mode also changes the way the Transmission works (Shifts at higher speeds) that will eat into gas mileage alone when on the freeway. If I am on the freeway and it goes into 4 cylinder mode, I do put it into Sport mode or just put the shifter into slap stick mode every 20 minutes or so for about 1 mile just to keep the cylinders from drying out due to no fuel on top. (Just a worry I have no proof it actually hurts them). In the spring I also drive it in Sport Mode for the first couple weeks I get it out after sitting all winter... Again no real proof it does anything....
 

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Discussion Starter #17
If you disable MDS should you replace the lifters in the center 4 cylinders? Just asking. For everyone saying to use "Sport Mode" to disable it manually, that is not really the same as disabling MDS by itself. As Sport Mode also changes the way the Transmission works (Shifts at higher speeds) that will eat into gas mileage alone when on the freeway. If I am on the freeway and it goes into 4 cylinder mode, I do put it into Sport mode or just put the shifter into slap stick mode every 20 minutes or so for about 1 mile just to keep the cylinders from drying out due to no fuel on top. (Just a worry I have no proof it actually hurts them). In the spring I also drive it in Sport Mode for the first couple weeks I get it out after sitting all winter... Again no real proof it does anything....
Keep the lifters. I just put mine into Auto Stick mode to get it out of MDS because it sounds awful. It's like a low frequency bass drone. It's the worst sound ever. Since I absolutely hate MDS mode I'm going to just disable it.
 
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