MDS Question

[68PowerWagon]

Ok the MDS shuts off 4 cylinders when load is not demanding. My question does the computer shut off the same 4 cylinders every time or does or does it alternate? I would think there would be some uneven wear if it shut the same ones off every time.
Another question does it work like a hybrid vehicle? They shut off while your idling at a red light does the MDS kick in & only run 4cyl. while idling?

 

[SilverStreak88]

The back 4 cylinders, does not go to 4 at idle and only becomes active at speeds 15MPH (I think) and over.

 

[cptwing]

Good questions, I'm gonna subscribe here as I am curious. Personally I think the whole MDS thing is horsecrap. As far as bang for the buck in gas mileage, it's a lot of exspense for almost no savings at all. And I do believe it will lead to premature failures.


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[Underarock13]

Correct me if I'm wrong I believe all brands use it now in gassers. I know Chevy does.

 

[2015HD]

Chevy does, it's called AFM and it sucks. One of the 1st things I did was buy a disable device for my Silverado. Correct me if I'm wrong, my 2015 2500 5.7 has VVT, is that another flavor of MDS?

 

[sbarron]

Good questions, I'm gonna subscribe here as I am curious. Personally I think the whole MDS thing is horsecrap. As far as bang for the buck in gas mileage, it's a lot of exspense for almost no savings at all. And I do believe it will lead to premature failures.


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Loads of high-mileage (well-maintained) MDS Hemi's in the world.


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[sbarron]

Chevy does, it's called AFM and it sucks. One of the 1st things I did was buy a disable device for my Silverado. Correct me if I'm wrong, my 2015 2500 5.7 has VVT, is that another flavor of MDS?

VVT is about engine efficiency. Nothing like MDS.


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[MN-Ram]

My 2011 Ram 1500 with a 5.7L had 87,000 miles when I traded it in for my new 3500. The only issue it ever had was a cracked exhaust manifold gasket. No problems related to the cylinder shut down. I never really noticed the MDS when I was driving either. I did see the mpg increase when I was driving 55-60mph. I do not see a big mpg change in my 6.4L though.

 

[68PowerWagon]

VVT=Variable Valve Timing? Advances & ******* the timing I do believe.

 

[Galion]

Chevy does, it's called AFM and it sucks. One of the 1st things I did was buy a disable device for my Silverado. Correct me if I'm wrong, my 2015 2500 5.7 has VVT, is that another flavor of MDS?

VVT is variable valve timing, basically it changes the timing of the valves opening and closing at different RPM's to increase power and fuel efficiency. It's unrelated to MDS and had been around for much longer too.

 

[68PowerWagon]

My 2011 Ram 1500 with a 5.7L had 87,000 miles when I traded it in for my new 3500. The only issue it ever had was a cracked exhaust manifold gasket. No problems related to the cylinder shut down. I never really noticed the MDS when I was driving either. I did see the mpg increase when I was driving 55-60mph. I do not see a big mpg change in my 6.4L though.

Mine on the 6.4 rarely kicks in. I am assuming this is due to the weight & increased wind drag of the HD's. This is why I was asking if it worked at idle. It might actually save fuel if it worked like a hybrid.

 

[drittal]

Mine kicks in a lot at 45, even some slight uphill.

At 70 it kicks in on level ground with no head or side wind.

At 80 you gotta be going downhill.

 

[MN-Ram]

Yeah, mine really kicks in between 45 and 60. Lately my EVIC has been saying I'm getting about 20mpg around 60mph. We'll see on my next long trip on back roads.

 

[Snyd]

Correct me if I'm wrong I believe all brands use it now in gassers. I know Chevy does.

Tundra 5.7 does not.

 

[chris1965]

Tundra 5.7 does not.

That's the reason why they never get better than 15mpg.

 

[SupermanWV]

My MDS must not work right. Best mileage I've ever gotten is 15 mpg. When truck was new. Now I'm between 7 and 10 mpg depending. That's with mix if in town and highway driving. No mods except for Magnaflow 18" muffler. I'd rather get rid of the MDS all together. But I have to deal with WV hills.

 

[RoadDog66]

SupermanWV, yea the hills kill the MPG's. The cold too (or maybe just the winter additives). I've got a mildly hilly 40 mile commute and even babying the throttle the 6.4 chugs like a frat boy. Unless the road is completely flat the MDS is useless.

 

[Underarock13]

Ahaha 15 mpg for a tundra is pretty generous ahaha.

 

[RodRam]

What weight oil are you running, thicker oils than 5-20 in the 5.7 make my MDS sluggish and hurt my mpgs.

 

[tjfdesmo]

What weight oil are you running, thicker oils than 5-20 in the 5.7 make my MDS sluggish and hurt my mpgs.

My 6.4 calls for 0W40.