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Old Nov 24, 2008 | 12:32 PM
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RLSH700
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Default RE: 5.7L break-in...MDS active?


ORIGINAL: downejt

Does anyone know if the MDS (multi-displacement system) is "active" during the break-in period? Wondering how this could affect ring break-in if certain cylinders aren't firing.

Also, RPM's seem to be staying relatively higher than I would expect during cruising....between 2,000-2,500 rpm. I have about 400 miles so far. Is this what can be expected after break-in period? Could be driving mpg down right now.

Any thoughts?
What speed are you at when it is running at this RPM. Something you have to remember is that the transmission has short gearing. Although it has a 3.06 axle ratio which is reasonable, the 5th gear ratio is a .83 (most overdrive ratios are traditionally around .7 give or take .03 to that). This is part of the reason why the manual is able to match the fuel economy despite not having the MDS because it has a 3.73 axle ratio with a .5 6th gear ratio which translates into a much taller combination. This is one reason why I was never crazy about the fact that they were planning on using this transmission to begin with.
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