Airmass

[30thta436]

Will someone please explain the torque coefficient airmass tables to me? What do they control and what do larger values and smaller values do to those tables?

[Ben Charles]

They control the tq model to some extent... Log engine tq and view it... Make a reduction to this table and view engine tq again and it will be lower.... Raise the table and engine tq increases...

Best way to mod this is to match engine tq of the engine in my opinion... This table controls everything..... Throttle, trans, etc from what I can tell...

This is what I have seen personally....
I have more info to provide, just want to see what other say and we can have a discussion.

[Ben Charles]

Also the GMVE plays with these tables I believe... As a test watch engine tq with a calibrated VE table vs one that is incorrect and notice the difference

[30thta436]

Best way to mod this is to match engine tq of the engine in my opinion... This table controls everything..... Throttle, trans, etc from what I can tell...

Are you saying modify it so that the engine torque being logged is equivalent to the amount the engine produces?

[Higgs Boson]

IMO, one might be surprised how much they can accomplish by leaving the entire torque model totally stock....A lot of issues with throttle and spark are really do to bad fueling and the ECM correcting. When everything is dialed in, you don't need to change the torque model....

900 rwhp on my car and stock everything on the tq model. I keep lowering my 100% row of the Driver Demand table and no throttle close yet.....although it is still quite a bit higher than stock.

[Higgs Boson]

Are you saying modify it so that the engine torque being logged is equivalent to the amount the engine produces?

That's what we were doing initially but IMO, don't worry about any of that. If your throttle is staying 100% open and your spark is what you are commanding and your AFR is in line....why change anything?

[Redline MS]

IMO, one might be surprised how much they can accomplish by leaving the entire torque model totally stock....A lot of issues with throttle and spark are really do to bad fueling and the ECM correcting. When everything is dialed in, you don't need to change the torque model....

900 rwhp on my car and stock everything on the tq model. I keep lowering my 100% row of the Driver Demand table and no throttle close yet.....although it is still quite a bit higher than stock.

I agree with Higgs,

First and foremost you need to fix the air models, both on MAP and APC. This whole game begins with the controllers ability to know the correct ingested airflow so it can correlate it to a torque value. The same what they use a coefficient formula to calculate the final GMVE the same is done for torque. The only reason why playing with the model "fixes" things is because you are robbing Peter to pay Paul. Let the controller do the math as long as you provide the right data for it to calculate it.

[GHuggins]

I too have found that "at least" with the gen 5's, you are far better off leaving the airmass tables alone and if you do modify them at all, only increase them at the most a 1/4 to what the general rule of thumb was for the gen 4's (percent of power added or actual torque being put out)... AND then I personally only increase them that slightly just for the trans shifting and line pressure holding benefits, which can be obtained through modifying the trans tables themselves. I do seem to have better drive ability with the slight increase. Keeps the trans from trying to shift too much and tends to pull the steep mountains around here much better? Now if you really want to cause some fun bucking and overly sensitive throttle inputs then increase these tables in conjunction to the dd tables and see what happens

[mowton]

I log Delivered Engine Torque vs MAP and RPM and validate against "reality, Dyno Torque printout by RPM, engine dyno sheet, google search etc. and adjust each (up or down in small steps) as required to "realign" after power changes and/or scaling. Again, most of my experience relative to this table is with Gen IV's, but am assuming the math is basically the same.....though you know what can happen if you ASS of U and ME...:-)

Ed M

[jarrah]

those are coefficients for the torque module they have been derived by gm to make sure stability of controlled system, I prefer not change them otherwise u can not ensure the convergence of the equations, I believe there should be a PID gains that we should have access to them in order to increase the response of the system rather then just change those coefficients blindly. some people reported increasing the values increases derived torque sure it does since it multiplies with higher numbers it result in a higher torque value but not necessary the correct one. the way to tune those I believe is the use of an engine dyno and using Simulink to solve fore 4 dof equations

[cmitchell17a]

It seems like the only time these would need changing is for something like a compression change or different pistons. If you change a cam or something like that, these should stay stock since the engine will see a higher airmass and calculate the correct torque from the stock table, but if you changed compression you would need to increase the coefficients since the engine has no way to tell its actually making more torque?

Is this correct thinking?