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For those of you with the EVIC who use the advanced menus by pressing the lower inner buttons, I have a question about the screen that shows Economy/Performance and has a left to right bar that fills from left to right.

When I first found this screen, I assumed it to be telling me when I was in MDS and when I was not. My assumption was Economy meant 4-Cyslinders and Performance meant 8-Cylinders, but I find it odd that when I hit the gass hard on the highway to pass, the economy kicks in and the performance is on when cruising at 70-75.

Can one of you experts please tell me how to read this screen properly and what the bar is showing me?

Thanks
 

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For those of you with the EVIC who use the advanced menus by pressing the lower inner buttons, I have a question about the screen that shows Economy/Performance and has a left to right bar that fills from left to right.

When I first found this screen, I assumed it to be telling me when I was in MDS and when I was not. My assumption was Economy meant 4-Cyslinders and Performance meant 8-Cylinders, but I find it odd that when I hit the gass hard on the highway to pass, the economy kicks in and the performance is on when cruising at 70-75.

Can one of you experts please tell me how to read this screen properly and what the bar is showing me?

Thanks
Well my question is similar...I can be cruising at 65-75...and Fuel Saver Mode will enable...but after a minute it will switch off...then turn back on...it keeps going on and off...i tried put on cruise for 65mph and it does the same...when i hit the gas to pass...i never see fuel saver mode...hope someone knows this well
 

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I do not know if I can answer the first question, but I think that depending on the roads that you drive in and you have a car cruise control set to 70, then everything there is an incline on the road, the fuel saver turns off because it has to accelerate, and then once it gets back to the speed set, it doesnt have to accelerate anymore. I think... Makes sense in a way...
 

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Well my question is similar...I can be cruising at 65-75...and Fuel Saver Mode will enable...but after a minute it will switch off...then turn back on...it keeps going on and off...i tried put on cruise for 65mph and it does the same...when i hit the gas to pass...i never see fuel saver mode...hope someone knows this well
MDS will periodically switch off to "recharge" the closed cylinders. This is with a steady pedal. It will happen maybe once every 4-5 minutes or so, maybe even longer.

However, cruise control does not work to favour a steady pedal, it works to favour a steady speed. So MDS will shut off quite often when on cruise control, more often as you reach higher speeds.

It's interesting to note the MDS activity versus pedal position. At 60, the threshold to turn on MDS on my '06 is 17% or lower. The threshold to kill MDS at that speed is about 22%. I can drive for really long periods of time cruising at that speed using 15-16% position readings, and occasionally dip into 20% or so on inclines. I'll lose 1 or 2 mph at that incline but hopefully regain it on the way down. MDS remains on. However, with cruise control, that pedal position will be varying constantly, from 13% to 17% to 20%... all in the name of keeping that speed. So on those occasions where it has to blip above 22%, ballgame over for MDS until it comes back down to below 18%.
 

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MDS will periodically switch off to "recharge" the closed cylinders. This is with a steady pedal. It will happen maybe once every 4-5 minutes or so, maybe even longer.

However, cruise control does not work to favour a steady pedal, it works to favour a steady speed. So MDS will shut off quite often when on cruise control, more often as you reach higher speeds.

It's interesting to note the MDS activity versus pedal position. At 60, the threshold to turn on MDS on my '06 is 17% or lower. The threshold to kill MDS at that speed is about 22%. I can drive for really long periods of time cruising at that speed using 15-16% position readings, and occasionally dip into 20% or so on inclines. I'll lose 1 or 2 mph at that incline but hopefully regain it on the way down. MDS remains on. However, with cruise control, that pedal position will be varying constantly, from 13% to 17% to 20%... all in the name of keeping that speed. So on those occasions where it has to blip above 22%, ballgame over for MDS until it comes back down to below 18%.
Ahh okay, well I guess even when u believe the road to be straight with no inclines....ur vehicle will always find that little point where there is an incline...but that understandable...I guess Im gonna mess around with it and see how long i can stay on fuel saver mode :p
 

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Ahh okay, well I guess even when u believe the road to be straight with no inclines....ur vehicle will always find that little point where there is an incline...but that understandable...I guess Im gonna mess around with it and see how long i can stay on fuel saver mode :p
Of course, the really interesting thing will be to actually compare over a long term (say, over a month each trial) whether it's more economical to drive long distances with MDS on at a certain speed (more or less) or to have it on cruise control and give it permission to drop out of MDS more often.

Tough thing to verify... resetting the EVIC doesn't start off the MPG reading from the immediate instantaneous mileage, it actually drops or increases from the previous value. So one cannot take single trials as final results, it would take a larger spread (like, a month or so).

It might be argued that staying in 4cyl mode longer would definitely be more fuel efficient, but then again MDS is programmed to deactivate periodically (for about a second or two) to "recharge" the shutdown cylinders (and perhaps warm them up?). So cruise control results in more frequent MDS shutdowns (for about the same length of time)... maybe that in itself would result in better overall results? Would be interesting to know...

Anyway, one thing for sure... there have been quite a few commutes where I've reset my EVIC before leaving work, and then gotten home to see 27.x MPG on my display. Often enough to know it wasn't a fluke. And I never use cruise control, so maybe there is something to be said about steady-pedalling it over relying on cruise control on this car?
 

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For those of you with the EVIC who use the advanced menus by pressing the lower inner buttons, I have a question about the screen that shows Economy/Performance and has a left to right bar that fills from left to right.

When I first found this screen, I assumed it to be telling me when I was in MDS and when I was not. My assumption was Economy meant 4-Cyslinders and Performance meant 8-Cylinders, but I find it odd that when I hit the gass hard on the highway to pass, the economy kicks in and the performance is on when cruising at 70-75.

Can one of you experts please tell me how to read this screen properly and what the bar is showing me?

Thanks
This screen has nothing to do with the MDS. Give it gas and its in performance. Let off gas its in Economy. I had my car in 2nd gear going down hill and it was in economy. Its like the old vacumm switches for the gas pedal in the 70's. It was fun to watch the needle move back and forth with the pedal. Just eye candy.
 

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MDS NORMALLY disables itself periodically, to keep the de-activated cylinders at normal temperature and to recharge the air in the shut-off cylinders, which acts as a spring.

From one of the ORIGINAL MDS design engineers:

http://www.lxforums.com/board/showpost.php?p=58320&postcount=11

magnumrt said:
The MDS system is much more complicated than most people realize. The design of the system took MANY more years than you may think, I actualy started working on this system back in 01 in some DC concept vehicles. Trust me, there were many issues to try and get it right. One of the requirements for this system was the electronic throttle controll. When you deactivate 4 of the 8 cyls, you get about a 50% reduction in air requirements meaning that when you hold your foot on the gas at 25%, in V8 mode, the throttle blades are at about 25% open, but when you go into 4cyl mode, we need to immidiatly adjust the throttle to about 15% throttle without YOU fealing it. This is an extreamly complex algorithm and is QUITE heavy in closed loop feedback with the MAP sensor, Crank/Cam position sensors, Input/output shaft speed sensors, etc. Also when you move from 8-4cyl there is obviously less vacuum being drawn by the motor. Lower vacuum to the MAP sensor is translated normaly as a higher load on the motor, but you need the PCM to realize that this is not the case at this particular moment. Now, as far as your question of why the motor doesnt stay in MDS longer to give you better fuel mileage? That is another compicated story that has been tuned quite extensively to give the best overall gas mileage without issues. When the lifters cut out and trap exhaust gasses in the cyl, that gas acts as a spring to keep the motor from wasting energy while the inactive pistons are going up and down. This gas begins to loose it's energy because the cyls will tend to leak a bit (through the rings and through the valves). The motor needs to re-initialize the cyl to allow the spent gases to escape. Now, the question is, why do you not re-initialize right away to save more gas? Simple, you gotta keep the engine's temperature equal so that you dont have 4 cyls working at a different opperating temperature than the others. The 4 cyls that are not firing will get cold as well as the valves, intake runners and specificaly the exaust pipes. Cold exhaust pipes dont flow as well as hot pipes and therefore you get an imbalance in those 4 cyls when running in V8 mode. The timing has been optomized for all these conditions to occur as transparently as possible. Extending the MDS time or frequency would end up creating more problems than are apparent to most.

So yeah, in conclusion.... It aint easy to do, there wont be any way for quite some time for you to increase the amount of time the MDS turns on for the simple fact that the design aint simple ;-) Not to mention the strategy has been developed to be as optimal as it could be. Trust me, the goal was fuel economy and transparency, TONS of time and effort went into making it as good as it can be.
 
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