MPG with your 3rd gen...

[SilverStreak88]

Yeah something isn't right then if that's all highway. If I keep my cruise on 60 I'll get around 18 even with the 35s. Depends on the road though.

Do you have a lot of idle time? Idle time kills mpg numbers a lot more than most people think. Also, the mds DOES work. I know people hate it and all, but on a correctly running truck it does make a difference especially on the highway. The people that say it makes no difference are the same people talking about they get 10mpg highway. No offense to anyone who has it disabled lol. Yeah it sounds bad, yeah it takes away some responsiveness, but it does help.

I have MDS diabled and I can say without out doubt from hand calculation that when it was ON (just about a month ago) I was sitting around 10. In all honesty the MPG I have ever gotten was 16.5 highway and that's when I got the truck bone stock in 09. Idle time does kill it, but I have no choice with traffic, I'm getting some Arch Oil and trying it out to see what it can do... I may just park it and buy a Smart Car.

 

[SilverStreak88]

Yupp and the 3.92 gears help.. I got 17-18 around town when it was just leveled. Now my highway is about 18-19 mpg.

I think a detailed DOT inspection of your rig is required for this one... I wanna see what you've got going on in there to get MPG's like that.

 

[justin13703]

I have stop and go traffic going back and forth to work. I always start my truck while making coffee to get everything going and warmed up a bit.

Your numbers may be fine then. Stop and go traffic both ways daily combined with letting it idle before work daily is exactly where your mpg is going. I'd say your truck is probably fine.

The mds topic is tricky because it is so touchy that some people, depending on driving style, will never get it to activate. Your general commute of mostly idling and stop and go traffic will not see mds ever activate so you'll see no difference by disabling it. When you can get on the highway, set the cruise, and just hang out with mds activated constantly, it does make a difference. Also, I noticed that since I put my 35s on mds barely kicks on anymore. Another time when disabling it will make little to no difference. Your tires are basically 35s as well.

 

[SilverStreak88]

Your numbers may be fine then. Stop and go traffic both ways daily combined with letting it idle before work daily is exactly where your mpg is going. I'd say your truck is probably fine.

But on a 4 hour drive to my land I maxed out at 14, coming back I turned MDS ON and got "about" 12.

 

[blackbeautyhemi]

I think a detailed DOT inspection of your rig is required for this one... I wanna see what you've got going on in there to get MPG's like that.

Lol I wish I still had the pic of my mpg display when it was just leveled and I took it to the beach, I had over 23 mpg on the way there and back. My hand calculation on the way back actually gave me .5 mpg higher avg than the display did. I just had exhaust, cold air intake and the programmer with the leveling kit at that time.

 

[justin13703]

But on a 4 hour drive to my land I maxed out at 14, coming back I turned MDS ON and got "about" 12.

Was this when you had your 295/70/18s?

 

[SilverStreak88]

Was this when you had your 295/70/18s?

Yep... about 3 weeks ago

 

[justin13703]

Lol I wish I still had the pic of my mpg display when it was just leveled and I took it to the beach, I had over 23 mpg on the way there and back. My hand calculation on the way back actually gave me .5 mpg higher avg than the display did. I just had exhaust, cold air intake and the programmer with the leveling kit at that time.

I've gone on a trip to Lancaster pa and back when I was on my stock wheels and got 21.3 hand calculated so these numbers are completely doable.

 

[justin13703]

Yep... about 3 weeks ago

Right there is why you didn't see any positive difference when you turned your mds back on. It probably hardly ever activated.

 

[SilverStreak88]

Right there is why you didn't see any positive difference when you turned your mds back on. It probably hardly ever activated.

Why is that? It came on plenty, but it was usually going down hill or on flats.

 

[blackbeautyhemi]

I've gone on a trip to Lancaster pa and back when I was on my stock wheels and got 21.3 hand calculated so these numbers are completely doable.

Yea so add the intake, programmer and exhaust gains it puts me where I said. That's funny cause my trip started just north of Lancaster to Maryland lol

 

[justin13703]

Why is that? It came on plenty, but it was usually going down hill or on flats.

Just because the added weight and rotating mass of the bigger tires cause you to use more power than when the smaller, lighter factory wheels and tires were on there. This will cause the mds to come on much less often. I've noticed mine doesn't come on near as much now that I have the 35s.

Just putting my ideas out there. But honestly I believe your numbers are ok when you take into account the idling and stop/go traffic. As far as them being low on the highway, this could just be because the highways you use are maybe more hilly than some others? This causes highway numbers to fluctuate a lot from one area to another.

 

[SilverStreak88]

Just because the added weight and rotating mass of the bigger tires cause you to use more power than when the smaller, lighter factory wheels and tires were on there. This will cause the mds to come on much less often. I've noticed mine doesn't come on near as much now that I have the 35s.

Just putting my ideas out there. But honestly I believe your numbers are ok when you take into account the idling and stop/go traffic. As far as them being low on the highway, this could just be because the highways you use are maybe more hilly than some others? This causes highway numbers to fluctuate a lot from one area to another.

Thank you for that - yes I have taken into account for tire size and all that, but I still think I should get a little better. Going to my land is the hill country so it's always down shifting, but I'll usually not use CC going through there. I have already decided that when these tires wear I'm going back down to OEM size.

I never thought about the extra weight effecting the MDS as you stated above, but it makes sense.

 

[justin13703]

Another thing I just thought of lol, I see that you have a tuner. I'm guessing you have your speedo corrected for the bigger tires? I'm asking because if it's not, you will go more miles than your odometer tells you, which will make both the overhead display and hand calculated mileage show lower than it actually is. But I'm assuming this isn't an issue because you probably have your speedo corrected.

 

[usaf2006]

All this talk makes me want to lower my rcsb... lol

 

[SilverStreak88]

Another thing I just thought of lol, I see that you have a tuner. I'm guessing you have your speedo corrected for the bigger tires? I'm asking because if it's not, you will go more miles than your odometer tells you, which will make both the overhead display and hand calculated mileage show lower than it actually is. But I'm assuming this isn't an issue because you probably have your speedo corrected.

Actually with the tires I have now the speedo is correct without calibration. I checked it without adjustment to a speedo sign we have down here and it's dead on. When I set it to the exact size of my tire it's off by 4 or 5 mph (can't remember exactly). Not sure how that works, but I leave it alone.

 

[SilverStreak88]

All this talk makes me want to lower my rcsb... lol

Good aero with it...

 

[xb1230]

All this talk makes me want to lower my rcsb... lol

You bet !

 

[stev0n]

stock 4.7, 3.92, 265/70-17s. my best so far has been 11.5mpg.

just replaced spark plugs & pcv valve before my last tank, never got above 2k rpms except doing 65 on the interstate... 9.7mpg for the tank according to my gas buddy app.

 

[usaf2006]

Do ya think a 3/4.5 drop would make a difference? I could run 245s as compared to my 265s with the lower height.