Quote:
ORIGINAL: HankL
There is a past post out there somewhere
where a Magnum 5.7 MDS owner with an aftermarket
"ScanGauge" studied what engine conditions were necessary for MDS to engage, and if memory serves me right
he posted that the PCM computer needed a minimum oil pressure (maybe 40 psi?) and that by 'hacking' the oil pressure sensor with a resistor similar to the old IAT hack it was possible to keep the MDS from engaging.
Don't take this as a recommendation that MDS should be removed, or that it is somehow bad, or that skilled re-programmers can't make MDS and high performance modifications work together....all of that is false.
What MDS does is give the typical owner about half the MPG improvement he would get if his transmission, diff and tires all had the optimum ratio for part-throttle highway cruise.
If MDS gives you a 2 MPG boost at 70 mph....you could get a 4 MPG boost if the drivetrain ratios were optimum...but with the optimum ratios you have to downshift to pass vehicles or climb steep hills.
It is worth noting that CVT gives optimum MPG, and Chrysler admits this by purchasing CVTs from the Jatco division of Nissan....but the CVT can't give instant power as quickly as MDS can.
The double drive shaft DirectShift manual transmission developed by the USA company Borg Warner for Volkswagon gives nearly instant power shifts...but they always have a jerk.
Chrysler announced last year they were developing a trans similar to the DirectShift.
The multi-mode transmission jointly developed by Chrysler/GM/BMW has other tricks to give nearly instant power boosts to engines that were cruising at part-throttle
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I'll tell you what, that Mercedes Transmission that they put in the Dodge Nitro R/T's will full electronic shifting is awesome. I test drove one a couple of times, and every time under every condition the second you touched the throttle, the power was to the wheels, always in the right gear, never downshifting or jerking.
I'm still not convinced with CVT's, They are OK in light cars, but I don't think they belong in Heavy trucks/suv's. CVT's have been around for a very long time in the snow mobile industry, and more recently in the ATV industry. But I speak from experience, when you put them under load, the fail every time. With a gear transmission, When you put power down, it transfers that power to the wheels, if there is not enough traction, the wheels will slip, Somethings got to give... Well on a CVT what gives is the drive belt, If you tires have alot of traction, instead of the tires slipping, the belt will slip and burn up the belt/pullies.
-ThaChad