Another_User

I have been looking over your posts, which have some good stuff, but there really isn't much about the affects of changing the Dynamic Airflow calculation and filtering values. Maybe even a comparison of Z06 screenless MAF values, and screened MAF values, with an idea of what the differences do? I understand if you are too busy...it's not a simple subject. I am just having trouble determining how the values are used in filtering and calculation so that i can make proper changes.

WS6snake-eater

I'm with you on this one. While he's there, if he could explain the dynamic airflow zoning a little more, it would be appreciated.

pknowles

iTrader: (1)

I agree. I don't understand why the boundries are so different between a F-body and a vette. I do know that the dynamic airflow calculation favors the MAF more in the mid and high rpm boundries. I deturmined this from using an off calibrated MAF table, changing the boundries and watching the trims. At this point it's still a shot in the dark without knowing what the PCM is doing different in different zones.

WS6snake-eater

I kind of suspect that the boundries are used to serperate how much maf vs ve blending is going on. But the way the are set from the factory does not leave much resolution. I was thinking about setting them to create more resolution, but I'm not too sure about the co-efficients, and filters, and how they effect each particular boundry. I have read the help file for the dynamic airflow section at least 10 times, and I still don't get it.

Another_User

What really gets me is how do you know how the filter is applied. gameover...could you give us some info? Pretty please?

Another_User

Up up up. I won't be letting this thread die so easily.

Another_User

Sooo quiet here...

Redline-Motorsports

iTrader: (3)

Who is he??

Another_User

One of our trolling experts.

Another_User

Ttt!!

CAT3

iTrader: (9)

TTT for this one as curiousity peaks.

Charlie

gameover

time is not on my side at the moment

From the help file:
"As engine operating conditions change the current zone changes and this selects the appropriate filter equation to be used in the dynamic airmass calculation"

The thing here is that we are still missing the filter equation coefficient table from the editor. At 1.6 we couldn't work out an easy way to display it in the editor as it is a little funky.

When we add it, you will still need a degree in linear predictive filtering and have access to something like MatLab to see the transfer functions and understand them. Although i will do my best to explain it...

Cheers,

Chris...

WS6snake-eater

Ok; then is there anything to be gained by changing the boundries? What effects would we see?

Another_User

I have been pondering that for awhile. I *think* that the zones determine how much filtering is done. More in some, less in others. I think it may affect how smooth the engine runs by more effectively using filtering based on engine characteristics and how well the engine transitions through different running conditions. Of course this is just speculation...the HPTuners guys are holding the keys to the car.

Uhm...if it's not too much trouble...I don't suppose we could get some more info on O2 calibration...I am seeing some interesting possibilities there as well...

Anyways...I'm still waiting to pick out my J-body...

pknowles

iTrader: (1)

Matlab is an incredible program. I used it to help me build my MAF table and obtain least squared fits of the data. I use it all the time for work and consider my self an advanced user of Matlab.

Filtering can be complicated, but most of the time it's a series of common known filtering methods. I don't know your background Chris (although I know you guys are great programmers and hackers), but I'm a PHD student working in experimental fluid mechanics and work with filtering my experimental data; although I don't do much predictive filtering. If it is with in my scope I wouldn't mind spending some time to help figure it all out. I'll have some time on my hands after finals in a few weeks.

P Mack

iTrader: (6)

I have matlab on my computer and i've dealt with filtering and transfer functions before on aircraft stability and control problems. I don't have a degree in it but i think i could understand enough for it to be useful.

gameover

i think i described it in another post around here somewhere but basically the filter is a predictive thing that predicts the new airflow value something like:

Airflow(t) = K1.Airflow(t-1) + K2.MAFair(t) + K3.MAFair(t-1) + K4.MAP(t) + K5.MAP(t-1) + + K6.MAP(t-2) + K7.TPS(t) + K8.TPS(t-1) + K9.TPS(t-2)

The K1-K9 values are selected from a multi-state table (18 states from memory) so you have 18 sets of coefficients dependant on engine operating conditions (zone). The thresholds and limits determine the zones and the coefficient matrix determines the airflow prediction. This table is not in the editor at present.

What you see from the filters is varying "favor" between the VE, MAF, TPS and MAP transients depending on operating conditions. eg. at steady state cruising the airflow weights towards the MAF heavily, but during other conditions terms from VE, MAP and TPS come into play to correct for the MAFs inability to accurately reflect cylinder loading during transients and situations where you may have large manifold/intake leaks.

It's an interesting thing, but the code is a twisty mess of 18 way state machine mixed with steady state detection routines and component failure bypasses. And LS2 is even more fun...

Chris...

Another_User

That's pretty much what i thought it did. I just was not aware of the mumbo-jumbo and mathematics behind it. What a headache. Nevermind...just keep working on v2.0, LOL!