Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (
-   Grand Cherokee - WK2 - (
-   -   "ECO" display on Hemi-V8 (

yodamel 04-24-2012 01:57 PM

"ECO" display on Hemi-V8
When the ECO display comes on, is this when the engine management program cuts off fuel supply to 4 cylinders in an effort to improve fuel economy?


ColdCase 04-24-2012 03:43 PM

Re: "ECO" display on Hemi-V8
Yes, on the V8 that is the indication. You can turn the indicator off in one of the EVIC menus if you want.

LaRADo 04-24-2012 09:12 PM

Re: "ECO" display on Hemi-V8
I am aware that the V6 does not shut down any cylinders, however mine still has the ECO light as well... is it doing anything in ECO or just telling me that I am at a lower fuel consumption due to lower RPMs and if I had a V8 it would be shutting down cylinders...?

ColdCase 04-24-2012 09:29 PM

Re: "ECO" display on Hemi-V8
The ECO light on the V6 is simply telling you that you are currently doing a good job driving for mpg. Nothing more.

On the V8 the ECO light simply indicates when the MDS deactivates cylinders, nothing more and nothing related to actual mpg.

BManz 04-25-2012 09:16 AM

Re: "ECO" display on Hemi-V8
The ECO light will come on for the Hemi even if MDS is not active but MDS will eventually activate if ECO stays on long enough and with a light engine load. There is a distinct change in exhaust tone when MDS activates and I've seen the ECO light on a lot without the MDS activated but this is at lower speeds (25-35mph). When MDS is activated, though, ECO is the definitely on. MDS activates/deactivates frequently when I'm driving but is subtle when it does so.

ColdCase 04-25-2012 10:30 AM

Re: "ECO" display on Hemi-V8
I have never seen the ECO light on without MDS also active +/- a couple seconds. At low speeds it is much more difficult to feel/hear MDS. But for the last 10,000 miles I've had the ECO indicator turned off, so I may have missed it.

jd2012jgc 04-25-2012 11:35 AM

Re: "ECO" display on Hemi-V8
Eco light does not always mean MDS is on, it means you're light on the gas pedal.
The MDS "hum" is an exhaust resonance drone due to the changed exhaust flow of shutting down 4 cylinders.

ColdCase 04-25-2012 12:37 PM

Re: "ECO" display on Hemi-V8
You don't always get a resonance with MDS, especially at the low rpm and speed mentioned here. You can't tell if MDS is active or not simply by exhaust resonance. You may be able to feel vibration when MDS is activated a low rpm, perhaps with a bit of throttle, you will notice the MDS kick out upon acceleration. Because its so difficult to determine if MDS is active under some conditions, similar to how difficult to tell what gear the transmission is actually using, observations may be anecdotal. Not so sure what the right answer is, and how much of a difference it makes.

All times are GMT -5. The time now is 10:34 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community