How can I retrofit the computer stategy to a non-MDS engine?

 

For the MDS to work, the selector MUST be in "D". The surge (or bump as I call it) is most likely occurring when the MDS is kicking off. Sometimes activation is noticeable in town, but not usually on the highway. At highway speeds the kickoff may occur concurrently with the torque converter coming unlocked, and be quite noticeable. In town the kickoff is more difficult to feel. I have the MDS "on" light and there are times when it goes off or on that I don't feel it at all. The MDS speed ranges on my RT are:
Sometimes, 16-19 mph So seldom I've not been able to figure out the parameters
Always, 22-28 or 29 mph Sometimes requires coaxing
Always, about 31-38 or 39 mph Sometimes requires coaxing
Always, above 42 and up to about 82 mph Very predictable
There are "dead spots" around all the shift points where it will not work at all. Those are the ranges between the numbers....20-21, 2-3 shift; 29-30, 3-4 shift; 39-41, 4-5 shift.

Also, you cannot retrofit the computer strategy to a non MDS equipped vehicle. Four of the cylinders have special lifters that are electronically controlled by solenoids as commanded by the PCM.

 

Also, you cannot retrofit the computer strategy to a non MDS equipped vehicle. Four of the cylinders have special lifters that are electronically controlled by solenoids as commanded by the PCM.
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I am aware of the Valve deactivation - I want to implement the MDS without this feature. I realize I may not get the full benefit of MDS.

What is the basis for your statement that the MDS - "cannot retrofit........"? "Cannot" is an action word for many of us to go ahead and find a way.

Let's see if we can find a way!

 

The 5.7 in the full size truck does not have MDS. Some aftermarket manufacturer may have that modification addressed when they come out with a tuneable computer / chip for the Magnums similar to the one used in the truck already. I would guess you cant just 'plug-n-play' a truck computer into a Magnum. There is probably some signal that needs to be sent to the valves that drop offline that is in the Magnum computer that is not there on the trucks.

 

rlsmith2212,
OK, sorry I used the word "cannot. All you need to have in addition to the MDS supported PCM (which by the way are vehicle unique) are the following components as indicated in the shop manual:

The main components of the Multi Displacement System are :
² Unique MDS camshaft.
² Deactivating roller tappets.
² 4 control valves/solenoids.
² control valve/solenoid wiring harness.
² oil temp sensor.

Have at it.

 

Does the MDS alternate which cylinders are shut down allowing for more even wear of engine componenets?

 

Magnuman,

I agree that doing the valve mod is not practical. But how about the other part? Adopt the Fuel cut out strategy to get part of the benefit. Remember with the valves closed the pressure builds up and is not released until the engine goes back to the 8 cylinder mode. By leaving the valves open and close normally it should be easier on the engine and may still yield some MPG improvements.

These are just some thoughts that may or may not make any sense!

Thanks for the info.

 

Ive not looked into it very hard, since Im satisfied with performance already. But, I think the 'deactivated' mode opens the exhaust valve so those cylinders pretty much free run. Since the pistons are still moving in the dead cylinders, Id say the wear should be pretty uniform. The only problem id see is carbon buildup in the dead cylinders more so than the full time ones, and the valve guides in those may wear slightly less.

 

When the pimply kid in the tuner car finally starts to catch up to you!

 

The valves stay closed. Cylinder pressure goes up and down with piston motion. That's to retain heat in the inactive cylinders to ease transition from active to inactive. The energy to compress the air in the inactive cylinder is returned as the piston goes down.