Originally Posted by myusername
honestly there is no way to know without a data logger like the dash hawk.
the TCM on the 5.7L stock works like this:
in D you are in full automatic mode (meaning car up/down shifts automatically based on driving style and programmed parameters) and MDS functions (it won't function if you come out of D, just FYI)
when you "down shift" into 4 or 3, all you are doing is telling the TCM to not go past that gear, so in theory making the car a 3 speed or 4 speed transmission..
as you slow the car will self down shift, and when at a full stop it will be in "1", as you accelerate it will shift to 2,3 when you hit the rev limiter, regardless of whether you bump it to + or not, and if in 3 it stops there, if in 4 then it will shift from 3 when you hit the rev limiter.
it doesn't hold the gear, and it won't shift past the selected gear, and it won't allow MDS to engage. and going from 4 to D doesn't upshift unless the parameters for 5th are met, additionally if you downshift and the computer believes the shift will over rev the motor past 3,000 (might be 3,500) rpm, it will hesitate the downshift until the computer thinks it's safe to do so, it is not instant on command shifting.
MDS will engage in any gear while in "D" as long as the programmed parameters are met, some of them being peddle position (under 12% as I recall, this can be seen in the EVIC hidden screens) RPM's under 3,000, and no load on the engine (i.e. climbing a hill for example).
now the diablo settings, which is also how the SRT TCM functions:
when you are in "D" your are in full automatic mode(meaning car up/down shifts automatically based on driving style and programmed parameters) and MDS functions (if enabled on the diablo, mine is not I loathe MDS) in the 5.7L of course the SRT doesn't have MDS.
now the difference, with the Diablo/SRT programming, I can bump my gear shift right toward the "+" side and it will dip into manual mode in my current gear, that is it doesn't down shift it stays in the gear you are in, if I go left to the "-" side it downshifts.
that's difference #1
#2 it holds whatever gear I am in until I shift (there is a selection in diablo for it to auto kick the gear as well if you choose to use it) meaning it will hit the rev limiter and bounce off of it like a true manual with a clutch..
also when downshifting or upshifting, unless it causes the engine to go beyond redline it will downshift almost instantly, so basically instant on command shifting.
#3 you can go into "5" after "4" instead of from "4" to "D"
#4 it behaves as close to a clutch manual as you can get, I can downshift into a hard corner and whip the backend around the corner (power slide) I can hold 1st in a standing (power brake) burnout and it won't shift or fall on it's face @ 5500 rpm, I can wind it up to 6200 without issue. and as stated I can baby it into the next gear around 1100 RPM and not be denied the shift, or have to wait until the computer nanny thinks it's ok.
basically it returns control back to the driver to decide how to beat the hell out of the car..
using a Dash Hawk it will tell you current and target gear, target gear pops up when the computer decides it is safe for the next upshift, as I stated, in "D" it simply will not do this under 50mph, now the disclaimer, I drive a 2004 early build 2005 model, there are tons of changes that have been made progressing over the 6 years this car has been in production, some of which have been how the TCM behaves under various conditions.
most of those changes, especially regarding TCM and MDS took place in late 2006/2007 models, and more drastic changes occurred in 2008 to present models..
now I am not saying I am the foremost authority on this, but I have over 6 months of data logging, testing, and tweaking using the diablo, star scan, and dash hawk trying to make the car behave the way I wanted and trying to boost my mpg..
I find it incredibly sad that this is 2010 with all the technology we have around us and this 5.7L car gets similar mpg to my 1985 Ford Crown Victoria with a 5.8L 351.. this car weighs less, is more aerodynamic, has a much improved fuel delivery system, yet in my Ford Land Yacht I get 12 - 14 city and 22 - 23 highway.. same as I manage on my 300c
Last edited by Mr. iNCREDIBLE; 10-01-2010 at 06:23 PM.
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