mpg's with MDS turned off

operator · Jan 18, 2014

does anybody know their avg mpgs with MDS turned off do u get better or worse? took my first trip since having my flow master super 44 installed and the 4cylinder sound doesn't bother me its just that when I set cruise control to 75mph or higher MDS doesn't engage as my rpms stay at 2000 the whole time. Is this normal? what kind of numbers do you guys running tuners get?

NYCruiser · Jan 18, 2014

You won't see an RPM drop when it engages. Ideally, you won't really notice it unless you are paying attention. Maybe notice a slight vibration, or different tone to the exhaust. Also ECO light will be on. You may sense a slight hesitation on accelerating out of it as it comes off. First it tries to accelerate on 4 cyl's for a sec then kicks off.

operator · Jan 18, 2014

NYCruiser said:
You won't see an RPM drop when it engages. Ideally, you won't really notice it unless you are paying attention. Maybe notice a slight vibration, or different tone to the exhaust. Also ECO light will be on. You may sense a slight hesitation on accelerating out of it as it comes off. First it tries to accelerate on 4 cyl's for a sec then kicks off.

that's the thing after 73mph my eco light doesn't come back on at all it stays off even when set to cruise

NYCruiser · Jan 18, 2014

Slow down. LOL

Mine definitely comes on, even at over 80mph if I take my foot off the gas.

operator · Jan 18, 2014

NYCruiser said:
Slow down. LOL

Its Louisiana I stay at 75 but u go anywhere below that 18 wheelers are passing & boxing you in along with all the other traffic I stay with the flow 70mph is creeping anytime I went out of town but I may try slowing it down a bit lol. but is there a certain cut off speed that MDS wont kick in?

bouf0010 · Jan 18, 2014

operator said:
that's the thing after 73mph my eco light doesn't come back on at all it stays off even when set to cruise

yeah im in the same boat as you - unless i start going downhill or theres a nice tail wind. Im pretty sure it doesnt kick in past 80 mph maybe even 75

As for the MDS - ive had mine off for quite a while now (tuned off) and ive noticed no drop in fuel mileage. In fact, hwy mileage is the same since i drive about 75-80mph all the time and in town seems to have improved by about 0.5 mpg.

NYCruiser · Jan 18, 2014

Not that I know of. As long as there is reduced load on the engine, it will kick in. If you have a lot of wind drag, or are climbing a hill, having your foot in it will prevent it from coming on. Also if you have the tranny in manual mode it is disabled. Maybe tow/haul too?

operator · Jan 18, 2014

NYCruiser said:
Not that I know of. As long as there is reduced load on the engine, it will kick in. If you have a lot of wind drag, or are climbing a hill, having your foot in it will prevent it from coming on. Also if you have the tranny in manual mode it is disabled. Maybe tow/haul too?

yea wish there was an option to keep it on when I wanted like a switch or setting I could use for long trips just hit a switch once im at cruise speeds and be able to turn it off at will

bouf0010 · Jan 18, 2014

operator said:
yea wish there was an option to keep it on when I wanted like a switch or setting I could use for long trips just hit a switch once im at cruise speeds and be able to turn it off at will

that might not necessarily be beneficial - lets say theres a high load on the engine, itll take a lot more work for those 4 cylinders to meet the demand and it might use a lot of fuel, at 8 cylinders the engine will have to work a lot less and might actually use less fuel.

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operator · Jan 18, 2014

bouf0010 said:
that might not necessarily be beneficial - lets say theres a high load on the engine, itll take a lot more work for those 4 cylinders to meet the demand and it might use a lot of fuel, at 8 cylinders the engine will have to work a lot less and might actually use less fuel.

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yea I guess your right maybe that's why im not an engineer for mopar lol. do you think the switch to my flow master from stock and me running reg tune with my bully dog on 87 octane has any affect on it? at all after I finish out this quarter tank that I have im gonna run it on plus gass which is 89 octane here super is 93 im just curious and I know a lot of guys here know about this sort of stuff this is my first hemi

bouf0010 · Jan 18, 2014

if anything it might kick on easier since youve increased the performance of your engine - less throttle required to get the same outcome. I didnt really gain much from a canned tune, but when I got my 93 performance tune from hemifever I gained about 1.5mpg, which is now negated by the fact that I drive the truck really hard cause its so much fun lol

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operator · Jan 18, 2014

bouf0010 said:
if anything it might kick on easier since youve increased the performance of your engine - less throttle required to get the same outcome. I didnt really gain much from a canned tune, but when I got my 93 performance tune from hemifever I gained about 1.5mpg, which is now negated by the fact that I drive the truck really hard cause its so much fun lol

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yea I thought about checking out the diablo tuner for that reason what type do u have the intune or the trinity? can the intune get custom tunes for the 2013

ericlee9386 · Jan 18, 2014

MDS is useless around town or traveling over 70 mph. My city mpg increased when I turned it off hwy stayed the same since I drive 80+ anyway. Truthfully no matter how fast I drive I get about the same mpg and oddly it seems I get the best when driving 85.

operator · Jan 18, 2014

ericlee9386 said:
MDS is useless around town or traveling over 70 mph. My city mpg increased when I turned it off hwy stayed the same since I drive 80+ anyway. Truthfully no matter how fast I drive I get about the same mpg and oddly it seems I get the best when driving 85.

what are you averaging highway if you don't mind my asking? I just don't want to turn it off and mess something up by having it off I don't know much about MDS I'm learning as I go along on this forum

NYCruiser · Jan 18, 2014

I usually drive on the highway at 70 and get low 20's on the computer with MDS on. I average under 15 around town.

bouf0010 · Jan 18, 2014

operator said:
yea I thought about checking out the diablo tuner for that reason what type do u have the intune or the trinity? can the intune get custom tunes for the 2013

I have the trinity. Both tuners will allow for custom tuning. The only difference is that the trinity will allow you to set up and live monitor various gauges.

operator said:
what are you averaging highway if you don't mind my asking? I just don't want to turn it off and mess something up by having it off I don't know much about MDS I'm learning as I go along on this forum

It wont mess anything up having it off.

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operator · Jan 18, 2014

NYCruiser said:
I usually drive on the highway at 70 and get low 20's on the computer with MDS on.

with it on going to baton rouge which is an hour north of me I averaged 18 mpgs with it on at 75 mph was wondering what people where averaging with it off and will it hurt my motor in the long run to have it off

NYCruiser · Jan 18, 2014

You can use the +/- tranny buttons to put your tranny in manual mode. Leave it displaying "6" and the tranny will operate normally, but MDS will never come on. See if you notice any difference.

ericlee9386 · Jan 18, 2014

operator said:
what are you averaging highway if you don't mind my asking? I just don't want to turn it off and mess something up by having it off I don't know much about MDS I'm learning as I go along on this forum

On the hwy I avg 18.1 during the winter and 20.4 during the summer and that's on 24's. I am in Northern La its more hilly here than it is down your way. Turning off the MDS has no side effects.

operator · Jan 18, 2014

ericlee9386 said:
On the hwy I avg 18.1 during the winter and 20.4 during the summer and that's on 24's. I am in Northern La its more hilly here than it is down your way. Turning off the MDS has no side effects.

ok one more question since installing the super 44 I notice my truck idles at about 715 to 730 rpms where as before with stock exhaust it stayed at 780 to 800 rpms at idle is this good or bad?

mpg's with MDS turned off

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