Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WK

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #1  
Old 01-06-2011, 07:14 PM
Member
My Jeep: 2007 5.7L WK
 
Join Date: Nov 2010
Location: Rome
Posts: 48
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 1537
Blutarsky is on a distinguished road
MDS Enable/Disable custom switch?

I've read about the custom led indicator to show when MDS is engaged and wondering if there would be a chance to build a custom switch to enable or disable MDS on the fly, without having to use tools such as Diablo or Superchips.

On my GC 5.7 HEMI - MY2007.

Any idea?
__________________

__________________
Reply With Quote
  #2  
Old 01-06-2011, 08:12 PM
Chaoul1's Avatar
The Original

My Jeep: 2010 6.1L WK
 
Join Date: May 2009
Location: Fairfax, Virginia
Posts: 6,913
Thanks: 2
Thanked 25 Times in 25 Posts
Rep Power: 63488
Chaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond reputeChaoul1 has a reputation beyond repute
Re: MDS Enable/Disable custom switch?

LOL. Press Tow/Haul. Seriously....
__________________

__________________
-Paul-
2010 Jeep Grand Cherokee SRT8

PaulsProfessional Automotive Detailing

PPAD's Custom Headlights

Contact for both DetailingPPADscustomwork@yahoo.com
Reply With Quote
  #3  
Old 01-06-2011, 08:20 PM
Member
My Jeep: 2008 5.7L WK
 
Join Date: Jan 2010
Location: mid-Michigan
Posts: 450
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 2285
Walt has a reputation beyond reputeWalt has a reputation beyond repute
Re: MDS Enable/Disable custom switch?

Quote:
Originally Posted by Blutarsky View Post
I've read about the custom led indicator to show when MDS is engaged and wondering if there would be a chance to build a custom switch to enable or disable MDS on the fly, without having to use tools such as Diablo or Superchips.

On my GC 5.7 HEMI - MY2007.

Any idea?
Manually shift from D to 5 will do it also.
__________________
'08 WK Limited, 5.7L HEMI, Quadra-Trac II, Bright Silver Metallic, Class IV Hitch, Michelin LTX M/S tires, Billet Technology oil catch can, Fumoto oil drain valve.
Reply With Quote
  #4  
Old 01-06-2011, 11:19 PM
Overboostin's Avatar
Member
 
Join Date: Nov 2010
Location: Rhode Island
Posts: 62
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1560
Overboostin is on a distinguished road
Re: MDS Enable/Disable custom switch?

What if you wanted MDS to stay on longer? It seems like mine is always shutting on and off, even when I'm not adjusting the throttle.
__________________
08 : Hemi : Overland : OME : Rancho : 33" MTR : Thule : SUV Racks : 6" Offroad Lights : D-Ring Shackle : Hi Lift : Midland : Firestik
Reply With Quote
  #5  
Old 01-07-2011, 04:04 AM
Member
My Jeep: 2007 5.7L WK
 
Join Date: Nov 2010
Location: Rome
Posts: 48
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 1537
Blutarsky is on a distinguished road
Re: MDS Enable/Disable custom switch?

Quote:
Originally Posted by Chaoul1 View Post
LOL. Press Tow/Haul. Seriously....
No mate, I've tried that, but RPM increase is unacceptable, IMO!

Quote:
Originally Posted by Walt View Post
Manually shift from D to 5 will do it also.
I've tried that but can't feel changes. I believe that that "D" and "5" are the same thing; when switching to "5" the computer is warning you that you are entering the "manual" mode, showing current gear, but nothing really changed. OR?

Quote:
Originally Posted by Overboostin View Post
What if you wanted MDS to stay on longer? It seems like mine is always shutting on and off, even when I'm not adjusting the throttle.
Correct, what's bothering is a feeling like the MDS is continuously switching in and out. If it could stay on constantly it would certainly be better, unless engineer at Chrysler have tested it and discovered the engine reacts like a mule...
__________________
Reply With Quote
  #6  
Old 01-07-2011, 04:23 PM
Senior Member
My Jeep: 2006 5.7L WK
 
Join Date: Dec 2009
Location: Home of the Mountain Blue Bird
Posts: 1,064
Thanks: 0
Thanked 26 Times in 24 Posts
Rep Power: 155089
jeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond repute
Re: MDS Enable/Disable custom switch?

I am the one that came up with the LED indicator for the LX's back in 2005, and later entertained the same idea you're addressing here. One of the guys (magnumrt) over on LXForums.com had been on the R and D team for the MDS sytem and put a halt to my plan. Here's his response to my original thread:

"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."

If you want to read more on this, you can see my (magnuman) original thread here: http://www.lxforums.com/board/showthread.php?t=11756

So, when you're cruising down the highway, not changing anything, things in the powertrain ARE changing, and the PCM is making adjustments accordingly. Just a couple are, the timing is continually changing resulting from ongoing sensor reads, and engine load varies with the slightest change in incline, wind conditions, timing, etc. If you hook up something like a DashHawk and continually monitor some of the powertrain functions, you'll get a better understanding of some of the variables and how they interact with one another. I've found that when all is said and done, most of it is way over my head. I just love to tinker and have enough knowledge to be dangerous.
__________________
05 LX/RT & 06 WK/GCO, modded similarly, MDS "ON" Light, Vortex Gens, Debadged, DashHawk, BT Catch Can, SRT CAI W/Add Air Inlet, K&N Filter, Sonnax Trans Press Booster, SC Tuner W/Adv Trans Tuning App, DS Tuner, Cust tube headers w/3 in. catback, Bilsteins, SRT frt/rear bumpers, Eibach SRT Lwr Sprgs & Sways, FRI Sidewinder Cam Adv 2*, 6.1 valvetrain, SLP 25% UD Pulley, BBK 90mm TB, SOS Coils/.060 plug gaps. 20 in. SRT Reps.
Reply With Quote
  #7  
Old 01-07-2011, 06:30 PM
Member
My Jeep: 2007 5.7L WK
 
Join Date: Nov 2010
Location: Rome
Posts: 48
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 1537
Blutarsky is on a distinguished road
Re: MDS Enable/Disable custom switch?

Nice one, jeepgcoman!

Some questions/comments:


- I believe about the efforts done. What it seems has been understimated by Chrysler is that many drivers could feel (badly) those transitions quite clearly. How could they ignore this?

- I wonder why some drivers comment about *NOT* feeling at all MDS transitions, maybe because they're not too sensible or maybe they own newer models, or what?

- Maybe it still could be a good idea to disable MDS by means of on-dashboard switch: leave it off in town, turn it on when wishing to feel a smooth driving. Could it be easily implemented?

My car is 2nd hand (MY2007), with PCM updated by 08-007-10 and will go through an oil change with proper 5W-20, however I strongly suspect this will not help, avoiding MDS jerking...!!
__________________
Reply With Quote
  #8  
Old 01-07-2011, 06:54 PM
Member
My Jeep: 2007 5.7L WK
 
Join Date: Nov 2010
Location: Rome
Posts: 48
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 1537
Blutarsky is on a distinguished road
Re: MDS Enable/Disable custom switch?

BTW, while awaiting for your next comment, I have been reading about the supposed MDS disabled when using the so-called "autostick mode" (forcing manual mode from "D" to "5").
Do you know if this is a myth or reality?
__________________
Reply With Quote
  #9  
Old 01-07-2011, 08:03 PM
Senior Member
My Jeep: 2006 5.7L WK
 
Join Date: Dec 2009
Location: Home of the Mountain Blue Bird
Posts: 1,064
Thanks: 0
Thanked 26 Times in 24 Posts
Rep Power: 155089
jeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond repute
Re: MDS Enable/Disable custom switch?

All I can do is relate my personal experiences with both my LX and WK. When my LX, with the NAG1 transmission was "totally" stock I could not feel the MDS kicking in/out at all. The NAG1 transmission IS NOT a true autostick unless you reprogram it with one of the tuners. In the stock mode there is no 5 position, so you cannot do the backshift trick. With either tuner (I have both DS and SC for both vehicles) the MDS becomes more noticeable, but the active parameters are expanded from stock. This is true for the WK too. Of course, incorrect weight oil will cause problems also, as will a vehicle that needs a tune up. A non-stock exhaust system will make the MDS operation very noticeable due to droning and exhaust pitch change.

I know there is a TSB for MDS operation on some of the WK's. You may want to check to see if yours is within that group. Also, just on general principles, you may want to have your PCM/TCM updated to the latest CALID flash files for your vehicle. When I bought my WK there had been 4 updates from the original. Granted, it didn't make a world of difference, but it did resolve some irritating accessory and driveability issues. Also, as far as the WK goes, my 06 GCO 545RFE transmission is not anywhere near an autostick, with or without the use of a tuner. It does not have a "5" position either way, and is not even close to being as good as the NAG1 in the LX. Maybe the newer 545RFE's have the "5" position. The LX with the tuner, has the "5" position. Without the tuner, it does not.

What I do in town sometimes is put the selector in "4". This keeps it out of MDS, and allows normal upshifts, as far as 4th gear. On either of mine there is only a slight difference in gas mileage in town, with or without the MDS. On the highway, the difference is substantial. Also, I don't know if you're aware, the 545RFE (as well as the NAG1) has a converter lockup feature. This can, and is, very noticeable on my WK, almost imperceptible on the LX. Some of what you may be feeling is the converter going in and out of lockup. This happens at all speeds and RPM's, and is accompanied by a bump and very slight RPM shifts up or down, depending on whether it's kicking in or out. On my WK this is much more annoying than the MDS operation. Knowing what they are and what to expect, I just try and ignore it. As far as it's benefit, it's probably about like the MDS.....little difference in town, more on the highway. I have made a half hearted effort to see how to manually control the converter lock, but haven't had the time to look closer. As someone stated above, pushing the "tow/haul" button eliminates the MDS (won't shift past 4th either) and the converter lock. It gives quite a different feel to the vehicle, IMO, but resolves both those issues. I also suspect there are other powertrain parameters changed too, some of which may not benefit gas mileage. One other thing with the converter lockup and MDS.....I have found that at some speed/RPM combinations they are trying to engage/disengage at the same time, which really makes for noticeable jerking, bucking, and MDS/converter lockup "hunting". I have found that I can get rid of most of this by using the Advanced Transmission Tuning App. in the SC tuner. By modifiying the upshift schedules, I have been able to pretty much eliminate these simultaneous operations.

You're right though, you'd think Chrysler would have resolved some of these issues before production. I wish they had put the NAG1 in all the WK's, not just the 3.7 and the 6.1. Maybe they have resolved them on newer models. Any of you newer WK owners have any input on this???
__________________
05 LX/RT & 06 WK/GCO, modded similarly, MDS "ON" Light, Vortex Gens, Debadged, DashHawk, BT Catch Can, SRT CAI W/Add Air Inlet, K&N Filter, Sonnax Trans Press Booster, SC Tuner W/Adv Trans Tuning App, DS Tuner, Cust tube headers w/3 in. catback, Bilsteins, SRT frt/rear bumpers, Eibach SRT Lwr Sprgs & Sways, FRI Sidewinder Cam Adv 2*, 6.1 valvetrain, SLP 25% UD Pulley, BBK 90mm TB, SOS Coils/.060 plug gaps. 20 in. SRT Reps.
Reply With Quote
  #10  
Old 01-07-2011, 10:10 PM
Member
My Jeep: 2008 5.7L WK
 
Join Date: Jan 2010
Location: mid-Michigan
Posts: 450
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 2285
Walt has a reputation beyond reputeWalt has a reputation beyond repute
Re: MDS Enable/Disable custom switch?

Quote:
Originally Posted by jeepgcoman View Post
....In the stock mode there is no 5 position, so you cannot do the backshift trick.... This is true for the WK too. ..... Also, as far as the WK goes, my 06 GCO 545RFE transmission is not anywhere near an autostick, with or without the use of a tuner. It does not have a "5" position either way..... Maybe the newer 545RFE's have the "5" position.... Maybe they have resolved them on newer models. Any of you newer WK owners have any input on this???
Just one:
On the '08 WK 545RFE xmission, moving the shift lever to the left now puts it in "5". I do that in town for slower speed driving to lock out MDS.
MDS can kick in as low as 24mph if conditions are right and the transmission selector is in "D".

Goes back to default when you start over. Since I grew up on stick shift, it's not a big deal for me.
__________________
'08 WK Limited, 5.7L HEMI, Quadra-Trac II, Bright Silver Metallic, Class IV Hitch, Michelin LTX M/S tires, Billet Technology oil catch can, Fumoto oil drain valve.
Reply With Quote
  #11  
Old 01-08-2011, 04:56 AM
Member
My Jeep: 2007 5.7L WK
 
Join Date: Nov 2010
Location: Rome
Posts: 48
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 1537
Blutarsky is on a distinguished road
Re: MDS Enable/Disable custom switch?

I own an export WH Model year 2007. I do have 5 gears with "5" appearing when moving the stick. Not sure about the exact transmission model.

I had applied latest patches to the PCM as soon as I read about the TSB that would address excessive transitions in the low speed range. That changed also the way the engine behaves looking like RPMs are now a little higher before gear changes.

Can you tell me more about the Advanced Transmission Tuning App? Very interested on this as I couldn't reproduce easily the jerking or identify a proper pattern, it may really be more problems happening at the same time.....
__________________
Reply With Quote
  #12  
Old 01-08-2011, 08:25 PM
Senior Member
My Jeep: 2006 5.7L WK
 
Join Date: Dec 2009
Location: Home of the Mountain Blue Bird
Posts: 1,064
Thanks: 0
Thanked 26 Times in 24 Posts
Rep Power: 155089
jeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond reputejeepgcoman has a reputation beyond repute
Re: MDS Enable/Disable custom switch?

Before you invest in a Superchips Tuner, you should contact them and confirm that it will indeed work on your export WH, and if it does, verify that the Advanced Trans. Tuning App. will also work. Next, you should verify that your WH has the RFE545 transmission. If the SC folks say everything will work, you have it. I can't imagine them putting something else in for export only.

If all is good, the ATT App. allows you to program up/downshift schedules to suit your particular needs and desires. The SC folks don't provide a lot of guidance, but there are plenty schedules available on these forums that others have come up with. You can try them or develop your own. This App. really makes the transmission more tolerable. When I made my shift schedules, I started by writing down the stock settings and after driving around awhile I made mental notes of where I thought the problems were and what I wanted to change. Then I made the changes in the App. and wrote them down, so I could make further adjustments, if needed. I think it took me about 3 renditions to get it where I wanted. Hope this helps you a little.

Regarding the jerking/bucking, I used to have the most problem with everything happening at once while cruising between 60-70 mph. There are a few spots (RPM/speed/incline, etc.) where the transmission would hunt between 4th and 5th gear. This would cause havoc with the MDS and the converter lockup clutch. They would activate/deactivate in response to the continual gear changes.
__________________

__________________
05 LX/RT & 06 WK/GCO, modded similarly, MDS "ON" Light, Vortex Gens, Debadged, DashHawk, BT Catch Can, SRT CAI W/Add Air Inlet, K&N Filter, Sonnax Trans Press Booster, SC Tuner W/Adv Trans Tuning App, DS Tuner, Cust tube headers w/3 in. catback, Bilsteins, SRT frt/rear bumpers, Eibach SRT Lwr Sprgs & Sways, FRI Sidewinder Cam Adv 2*, 6.1 valvetrain, SLP 25% UD Pulley, BBK 90mm TB, SOS Coils/.060 plug gaps. 20 in. SRT Reps.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
MDS Disable = 2mpg loss bluethunderjeep Grand Cherokee - WK 25 06-27-2010 01:43 AM
5.7 mds disable KidFresh5.7 Performance Modifications 3 02-21-2010 05:40 PM
How do I enable seatbelt chime again? White WK Swagga Grand Cherokee - WK 14 02-10-2010 01:10 PM
How to Disable MDS with Predator 06HemiLtd Performance Modifications 1 12-16-2009 04:16 PM
MDS Disable? 1 GRAND Performance Modifications 16 08-29-2009 08:01 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 11:45 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

JeepGarage.org is in no way associated with or endorsed by Chrysler Group LLC.