In a LMM, what is normal to see in the max requested Torque field when looking at the TCM data on a LMM with a Tech2? I was looking at a truck today with a friend that I KNOW was tuned based on the cal flash history in the ECM. What I'm not sure of is HOW tuned it was. In the TCM, it had a value if about 850ft/lb in the above mentioned field. My ASSUMPTION is that for a stock truck that has never been tuned, that number should be less than 700ft/lb. Am I correct?
LMM: TCM Max Driver requested Torque reading
- Thread starter Cougar281
- Start date
GMC_2002_Dmax
The Still Master
its a calculated value Tony based on acceleration rates, converter slip speed per pedal position/fuel rate, etc.
It doesnt just look at whatever is in B1105...
GMC_2002_Dmax
The Still Master
You could always change fuel rate tables or the actual pulse width and leave torque based fuel alone.
then what would the value be??
then what would the value be??
Well I tuned one and my torque based tables do not go over 800, yet the TCM had logged 956 for max torque input, so I'm with Ben on this one. The GEN IV TCM bases peak torque input off of the TAPS and other factors to come to a rough peak torque input, and the ECM output has no influence on it. This was specifically done so GM could tell if a tune was put in or not.
that would have no effect on the max torque reading.....because like I said..... (or maybe you werent listening).....its a CALCULATED value.
mass airflow sensor readings, throttle %, fuel rate, engine RPM, converter slip speed, turbine RPM, etc.
It factors in all of these and performs a bunch of complex calculations and can make a pretty good educated guess at how much torque the engine is actually putting out.
just like how if the TCM loses throttle % signal (obviously critical in determining shift points), it will actually default to an "educated guess" on what the throttle % is based on converter slip speed. Its pretty clever and actually fairly accurate at guessing (disconnect the high-speed databus wires going to the TCM and drive around, and you'll see how it can still shift and guestimate the proper shift points based on converter slip speed and vehicle speed alone)
Only the 2009+ A50 controller has this advanced "actual engine torque guestimating" feature in the software, but all Allison TCM's (both 5-speed and 6-speed) have the "default mode" in the software that allows it to still work properly if it loses all communications with the ECM and throttle % info.
But idk, tony says thats not how it works, so who knows the real answer...
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GMC_2002_Dmax
The Still Master
I never looked at one with a Tech2 but I would venture to say that unless you have a fully built trans with mods capable of 950 LB/FT of TQ then the calculation is scewed.
I'll see if I can get a few local LMM's with built trans and my tuning and see what they show.
Until I can compare and do some looking I will reserve any further comment, but it doesn't seem like the numbers will be accurate.
We shall see.
:hug:
I'll see if I can get a few local LMM's with built trans and my tuning and see what they show.
Until I can compare and do some looking I will reserve any further comment, but it doesn't seem like the numbers will be accurate.
We shall see.
:hug:
I wonder how a 300-400 higher stall converter would effect this even on stock ecm tuning?
they're going to have to be LMM's with the A50 controller. The A40/A41/A46 controllers dont do "torque calculations".
What im saying tony, is that its not what you were saying it was. You originally said it was "whatever the max value is that you (as a tuner) put in B1105"
Which is not true. Its a calculated value, determined by the TCM, that the ECM tune has no control over.
Obviously with a different stall converter than stock, the value will be skewed.
The point im making is, you cant "fool" this value with crafty efilive tuning (to make it look like a truck wasnt tuned)
ben
Wow, this exploded!
To get back on topic, weather it's based off the table in the ECM or it's calculated, the bottom line is if it's a stock truck that's never been tuned, the value should be less than 700 - probably somewhere in the 660 range since that is the stock peak torque - right?
To get back on topic, weather it's based off the table in the ECM or it's calculated, the bottom line is if it's a stock truck that's never been tuned, the value should be less than 700 - probably somewhere in the 660 range since that is the stock peak torque - right?
yes unless you have a trans problem or slippage that doesn't throw a code at which point the stategy may decide there is actually more torque there.
That is if I am Picking up what ole Ben is layin down
But yes 660 sounds like a good number
That is if I am Picking up what ole Ben is layin down
But yes 660 sounds like a good number