Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (http://www.jeepgarage.org/forums.php)
-   Grand Cherokee - WK2 - (http://www.jeepgarage.org/f73/)
-   -   MPH with MDS on WK2? (http://www.jeepgarage.org/f73/mph-with-mds-on-wk2-17093.html)

WK2 Rover 01-05-2011 08:16 PM

MPH with MDS on WK2?
 
ECO/MDS stayed engaged at 80 MPH while cruising on a flat dry highway! I have only had my Overland 4x4 a month but am pleased to be able to cruise this fast as a "four banger". And it was only running at 2100 RPMs at 80 MPH, 300 lower than my 2006 Lexus IS 350 with a six-speed transmission.

The EVIC showed about 22 MPG at 80 MPH, and 25 MPG at 65 MPH. More tick marks (15, 25, 30) on the display would help with these estimates.

Chaoul1 01-05-2011 08:28 PM

Re: MPH with MDS on WK2?
 
Remember, there's different gears on a Jeep!

Technosavant 01-05-2011 08:31 PM

Re: MPH with MDS on WK2?
 
Cruising at a constant speed takes very little power. Getting to that speed is much more demanding.

mjw930 01-05-2011 10:13 PM

Re: MPH with MDS on WK2?
 
Quote:

Originally Posted by Technosavant (Post 329081)
Cruising at a constant speed takes very little power. Getting to that speed is much more demanding.

Correct up to a point but drag is logarithmic, not linear so while it may only take 50 hp to maintain 70 mph it could take 100 to maintain 80. The fact it can lug down to 2100 rpm and switch to 4 cylinders and still maintain 75 mph is a testament to the aerodynamics of the new WK2.

Bmwister 01-05-2011 10:20 PM

Re: MPH with MDS on WK2?
 
Affirmative, Techno/mjw. It's how much horsepower one needs in order to maintain speed that is the key. That's why I laugh at all the talk of needing an 8spd transmission to lower engine speed on the highway; if you need 20hp at ~1500 RPM to cruise 60mph, you need 20hp and lowering the RPM more than that yields minimal/nil gains. Highway cruisng is where low-end torque helps fuel economy because with more potential torque at that low RPM, speed can be maintained without significantly increasing engine friction by running at a higher RPM.

jimoverland 01-06-2011 07:25 AM

Re: MPH with MDS on WK2?
 
Quote:

Originally Posted by WK2 Rover (Post 329064)
MDS stayed engaged at 75 MPH while cruising on a flat dry highway this weekend! I have only had my Overland 4x4 a month but am pleased to be able to cruise this fast as a "four banger".

And at 80 MPH it was only running at 2100 RPMs, 250 lower than my 2006 Lexus IS 350 with a six-speed transmission.

How do you know when MDS is engaged?

mjw930 01-06-2011 07:50 AM

Re: MPH with MDS on WK2?
 
Quote:

Originally Posted by jimoverland (Post 329303)
How do you know when MDS is engaged?

From the manual

Quote:

Display Fuel Saver— If Equipped
The “ECO” message is located in the Compass/
Temperature display, this message can be turned on or
off. To make your selection, press and release the FUNCTION
SELECT button until “ON” or “OFF” appears.
To be more precise, I think ECO or ECON is displayed in the EVIC display when MDS switches to 4 cylinder mode.

jimoverland 01-06-2011 08:03 AM

Re: MPH with MDS on WK2?
 
Quote:

Originally Posted by mjw930 (Post 329308)
From the manual



To be more precise, I think ECO or ECON is displayed in the EVIC display when MDS switches to 4 cylinder mode.


I think ECO is only a function of throttle position and RPMs. Milous (or any of the other Jeep guys), can you confirm this?

MDS only engaged between 40 & 60MPH on my WK and I'm pretty sure it only engages within a limited range on my WK2, too.

mjw930 01-06-2011 08:15 AM

Re: MPH with MDS on WK2?
 
Quote:

Originally Posted by jimoverland (Post 329310)
I think ECO is only a function of throttle position and RPMs. Milous (or any of the other Jeep guys), can you confirm this?

MDS only engaged between 40 & 60MPH on my WK and I'm pretty sure it only engages within a limited range on my WK2, too.

On the last WK2 demo drive I did there is a display in the EVIC when the vehicle goes into 4 cylinder mode, I"m pretty sure it said ECON and as noted by the OP he sees it at 75mph so the old WK restriction is obviously not there anymore. I was doing ~35 when I saw it.

Red G8R 01-06-2011 09:55 AM

Re: MPH with MDS on WK2?
 
As far as I know, ECO does not equal MDS.

mhassler 01-06-2011 10:12 AM

Re: MPH with MDS on WK2?
 
Quotes from the Manual:

MDS (if equipped) 5.7L Engine Only: "This feature offers improved fuel economy by shutting off four of the engine's eight cylinders duringlight load and cruise conditions. This system is automatic with nodriver inputs or additional driving skills required."

And under the EVIC Section:

- ECO = Fuel Saver Indicator

- Display Fuel Saver (if equipped): "The 'ECO' message is located in the Compass/Temperature Display, this message can beturned on or off. To make your selection, press and release the FUNCTION SELECT button until 'ON' or 'OFF' appears."

From this I interpret that ECO does equate to an active MDS.

CPT2010 01-06-2011 10:22 AM

Re: MPH with MDS on WK2?
 
Quote:

Originally Posted by mhassler (Post 329342)
Quotes from the Manual:

MDS (if equipped) 5.7L Engine Only: "This feature offers improved fuel economy by shutting off four of the engine's eight cylinders duringlight load and cruise conditions. This system is automatic with nodriver inputs or additional driving skills required."

And under the EVIC Section:

- ECO = Fuel Saver Indicator

- Display Fuel Saver (if equipped): "The 'ECO' message is located in the Compass/Temperature Display, this message can beturned on or off. To make your selection, press and release the FUNCTION SELECT button until 'ON' or 'OFF' appears."

From this I interpret that ECO does equate to an active MDS.


my 05 hemi, is the same, i can hear it shutting off cylinders...

Awesome news dude!


All times are GMT -5. The time now is 09:58 AM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community