For the guys who think deactivating the mds via a tune is a good idea

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Wild one

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Has anyone got any knowledge of oil flow in an mds engine when functioning in 8 cyl?
It is far more often than not that the engine operates with 8 cyl. so the mds solenoids are closed limiting pressurized oil to the lifter bore.
There HAS to be oil still getting to the lifters for proper lubrication of the engine.

I'm honestly contemplating buying a block just to study all this.
There is still some oil getting to the lifters,it's just not all of it,and the oil leaking past the solenoids when they're closed (MDS in-active) isn't at the same pressure as when the solenoids are open (MDS active)
 

Black1500Ram

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Look at my two posts in this thread.
Thanks, I've seen everything Reignited has put out on the topic...
I'm more interested in the engineering aspects of the engine
There is still some oil getting to the lifters,it's just not all of it,and the oil leaking past the solenoids when they're closed (MDS in-active) isn't at the same pressure as when the solenoids are open (MDS active)
just found this, just as an fyi
MDS explanation
 
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Wild one

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Thanks, I've seen everything Reignited has put out on the topic...
I'm more interested in the engineering aspects of the engine

just found this, just as an fyi
MDS explanation
That's about the best explanation of the system in regards to oil pressure that i've seen.Good find,and thank-you for adding that link to this thread Black
 

ramffml

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So there is at least 3 psi to the lifter bores at all times, they specifically say "This lifter oil keeps the bores lubricated..."

But as with all discussions on the hemi it seems, this article too doesn't get everything right: from experience, I can say that my engine doesn't care whether it runs 20, 30, or 40 weight oil; I get no codes, and about the same percentage of the time regardless of oil choice I get some shake when it deactivates (but never anymore when it activates).
 
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Wild one

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For the guys who maybe can't see Blacks link ,here it is.



MDS operation, an explanation.​


Most of us really don't have an idea of how MDS works in our Hemi trucks. Questions are always popping up about Eco mode, MDS, affect on the truck, when it works etc.

Did some searching around the web and found some interesting information on MDS. So here goes.



mds_graph2_zpsa3f52cfb.jpg



How Chrysler's Multiple Displacement System Works



In 2005, the Multiple Displacement System (MDS) version of the 5.7L HEMI engine was introduced on the Chrysler 300C and Dodge Magnum. This engine can deactivate four of the eight cylinders, and operate as a 4-cylinder engine during periods of low load, improving fuel economy and emissions. The MDS provides the 5.7L engine the fuel economy of a V6 while maintaining the performance of a V8. The fuel economy improvement is estimated to be up to 20 percent, depending on driving conditions. The MDS operation, invisible to the driver, is fully integrated into the fuel injection system.

"In 2005, the Multiple Displacement System (MDS) version of the 5.7L HEMI engine was introduced on the Chrysler 300C and Dodge Magnum. This engine can deactivate four of the eight cylinders, and operate as a 4-cylinder engine during periods of low load, improving fuel economy and emissions.”

When the MDS engine switches to 4-cylinder mode, the powertrain control module (PCM) controls solenoids that manage special "dual mode" lifters, allowing the intake and exhaust valves to remain closed on cylinders 1, 4, 6 and 7. There is one solenoid for each cylinder (two lifters). The PCM also deactivates the fuel injectors for these cylinders when in the 4-cylinder mode.

When the MDS solenoids are in the "off" state (8-cylinder mode), they supply oil pressure of approximately 3 psi to the lifter bores. This lifter oil keeps the bores lubricated and prevents air from entering the system. When the solenoids are activated, oil pressure of 16 psi or greater is supplied to the lifters and the engine enters the 4-cylinder mode.

When the special lifters are supplied high oil pressure by the solenoid, pins inside the lifter move inward. This unlocks the outer portion of the lifter and allows it to move independently from the center portion of the lifter. The camshaft can move the outer portion of the lifter without transferring motion to the inner portion of the lifter.

8-cylinder mode: Solenoids are in the "off" state (de-energized). Minimal oil pressure is applied to the special lifter. They are working normally in this mode.

4-cylinder mode: Solenoids are in the "on" state (energized). High oil pressure is applied to the special lifters and the lifters become inactive and essentially the four pistons are along for the ride. Both valves are closed.

The PCM will activate the 4-cylinder mode when the following enabling conditions are met:

Low engine load

1200 to 3000 rpm

Vehicle speed between 12 mph and 90 mph

Battery voltage from 9 volts to 15 volts

Oil pressure from 15 psi to 147 psi

Oil temperature greater than 120 F

Engine coolant temperature from 158 to 248 F

Ambient temperature from 14 F to 248 F

No throttle position sensor or MDS faults

The PCM deactivates solenoids one cylinder at a time in the firing order. If the system is "on" for long periods of time, such as a long flat road with no stopping, the system will return to the 8-cylinder mode approximately every six minutes to maintain engine temperature. The PCM will also unlock the torque converter before the transition, to minimize the effect on driveability.

The oil temperature sensor used for this system is a two-wire sensor, negative temperature coefficient, like the sensors for engine coolant temperature or intake air temperature (IAT). The PCM uses this input - along with oil pressure, load and rpm - to calculate oil viscosity and flow rate. This information is critical to MDS operation.

It's important to know this engine uses 5W-20 engine oil. If the wrong oil is used, fault code P1521 can be set, and the vehicle may show symptoms of a shudder - similar to a torque converter shudder - when the MDS system is activated and deactivated. Other symptoms may include MDS performance codes or engine misfire codes.

Before spending a lot of time with these codes, use the vehicle service history to find out what type of oil is in the engine. Because this is not always possible, the next best thing is to replace the oil (and filter) with 5W-20. This may have to be done twice to fully restore the system back to normal. Oil sludging, restricted oil passages or lifter contamination can also cause problems with this system.

Quick facts:

Each MDS solenoid has about 12 ohms of resistance. When the solenoid is activated by applying 12 volts to it, an audible "click" can be heard from under the intake manifold. This test can be done with a jumper wire or by using the actuator test mode (ATM) mode of a compatible scan tool.

If the solenoid is mechanically stuck in the "on" position, the result will be one dead cylinder.

Hopefully, this information will be helpful if one of these systems shows up in your shop.
 
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Wild one

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So there is at least 3 psi to the lifter bores at all times, they specifically say "This lifter oil keeps the bores lubricated..."

But as with all discussions on the hemi it seems, this article too doesn't get everything right: from experience, I can say that my engine doesn't care whether it runs 20, 30, or 40 weight oil; I get no codes, and about the same percentage of the time regardless of oil choice I get some shake when it deactivates (but never anymore when it activates).
Some of the earlier trucks will set a code for improper oil viscosity,but it seems to be only the 2009's and very early 2010's that have that issue. Anything after that seems to have no issues with 5W-30 or 0W-40 weight oils.
In fact Ma Mopar says 5W-30 is okay to run in them if 5W-20 isn't available.
 

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Marshall

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Drove my truck to work this morning with MDS still active, first time since I can remember not turning it off with gear +/-.

To and from work is about 20 minutes each way.

HATED it! On the freeway wasn't bad unless I was coasting or decelerating but surface street speeds... Good lord I need a muffler now.

MDS delete/cam/converter may be on the list soon.
I can't hear the difference, unless putting around slow, with window open.
I have never really noticed it on or off. the light will come on the dash
truck is stock
That is one thing with old age , a lot of stuff don't bother me, have other things , sore joints . need to stop way more often, wife pissed because I can't hear her.
I do turn it off a bit when truck is cold to get the RPM's up a little, may not be a good idea?
1200-1500rpm around town.

Before I moved, with the older ones, a trip to town was 1 hr on the highway, and I had old trucks for work and short trips.
I will watch those clips, seen one before.

One question, all mine have been 5.7's, is there any difference with the 6.4 in the trucks?
 
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Wild one

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I can't hear the difference, unless putting around slow, with window open.
I have never really noticed it on or off. the light will come on the dash
truck is stock
That is one thing with old age , a lot of stuff don't bother me, have other things , sore joints . need to stop way more often, wife pissed because I can't hear her.
I do turn it off a bit when truck is cold to get the RPM's up a little, may not be a good idea?
1200-1500rpm around town.

Before I moved, with the older ones, a trip to town was 1 hr on the highway, and I had old trucks for work and short trips.
I will watch those clips, seen one before.

One question, all mine have been 5.7's, is there any difference with the 6.4 in the trucks?
I'm hoping the "hear the wife thing" starts to kick in soon,she justs gets louder until i say i've heard her ,lol /
I think the 6.4's have mds,maybe once you get into the 3500's or heavier they don't,but i'm pretty sure the 2500's have mds
 

Lsujker

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I'm hoping the "hear the wife thing" starts to kick in soon,she justs gets louder until i say i've heard her ,lol /
I think the 6.4's have mds,maybe once you get into the 3500's or heavier they don't,but i'm pretty sure the 2500's have mds
The 2500 does infact have and its more noticeable compared to the 1500.
 

RamDiver

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I notice the switching of the MDS on my Warlock, it's quite annoying in traffic.

I live in the country so most of my driving is rural and it doesn't bug there.

Whenever I go to the big city (Ottawa) or the little village near my house, my truck stays in 8 cylinder mode.

It's a small percentage of my driving, can't be any worse than those that tow. :cool:

And, it's much more fun to drive with 8 cylinders. :cool:

.
 
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Wild one

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I notice the switching of the MDS on my Warlock, it's quite annoying in traffic.

I live in the country so most of my driving is rural and it doesn't bug there.

Whenever I go to the big city (Ottawa) or the little village near my house, my truck stays in 8 cylinder mode.

It's a small percentage of my driving, can't be any worse than those that tow. :cool:

And, it's much more fun to drive with 8 cylinders. :cool:

.
Calgary is close to 1/2 million larger then Ottawa and i hate driving it in,i even hate driving in Airdrie now as it's grown to close to 90,000 now,it was under 9,000 when we moved here 30 years ago,and it's not the same city it was back then,aarrgghh,lol. I own land in Saskatchewan and it's looking better all the time,even being in the middle of buttfluck nowhere.If my wifes family wasn't still in Calgary and Airdrie,we would of moved there years ago :waytogo:
 

Black1500Ram

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I can't hear the difference, unless putting around slow, with window open.
I have never really noticed it on or off. the light will come on the dash
truck is stock
That is one thing with old age , a lot of stuff don't bother me, have other things , sore joints . need to stop way more often, wife pissed because I can't hear her.
I do turn it off a bit when truck is cold to get the RPM's up a little, may not be a good idea?
1200-1500rpm around town.

Before I moved, with the older ones, a trip to town was 1 hr on the highway, and I had old trucks for work and short trips.
I will watch those clips, seen one before.

One question, all mine have been 5.7's, is there any difference with the 6.4 in the trucks?
You must not have an exhaust.
When MDS kicks in with the Carven it sounds aweful.
 

Docwagon1776

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I'm hoping the "hear the wife thing" starts to kick in soon,she justs gets louder until i say i've heard her ,lol /
I think the 6.4's have mds,maybe once you get into the 3500's or heavier they don't,but i'm pretty sure the 2500's have mds

2500s have it for sure. I never noticed it kick on at all in my 1500 5.7/6 speed. I can feel it in the 2500, especially once I added rock rails for some reason. Mostly just feel it through the gas pedal and a very minor vibration at times. Unless I'm paying attention for it, it's pretty much just a background thing. I mean, I drove a '71 IHC Scout as a daily for years so an occasional little vibration in the pedal isn't going to ruin a truck for me...
 

HEMIMANN

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Some of the earlier trucks will set a code for improper oil viscosity,but it seems to be only the 2009's and very early 2010's that have that issue. Anything after that seems to have no issues with 5W-30 or 0W-40 weight oils.
In fact Ma Mopar says 5W-30 is okay to run in them if 5W-20 isn't available.

But not lubricated enough, is the issue.
 

RamDiver

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Calgary is close to 1/2 million larger then Ottawa and i hate driving it in,i even hate driving in Airdrie now as it's grown to close to 90,000 now,it was under 9,000 when we moved here 30 years ago,and it's not the same city it was back then,aarrgghh,lol.

Maybe I should qualify my statement.

The switch itself is completely transparent, what I dislike is, when I tromp on the skinny pedal and it lurches and hesitates before launching.

I want instant satisfaction.


I own land in Saskatchewan and it's looking better all the time,even being in the middle of buttfluck nowhere.If my wifes family wasn't still in Calgary and Airdrie,we would of moved there years ago :waytogo:

BF nowhere sounds great but...

Will you try to commandeer Danielle Smith to go with you?

Most of her behavior has me tempted to move to the Alberta.

.
 
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