Air Calc Mode PID

[mowton]

What does the Air Calc Mode PID tell us?..will it differentiate between MAF and VE calcualtion for air flow? Is it granular enough to tell me difference between dynamic and steady state?

Thanks,

Ed M

[Chris@HPTuners]

it tells you if you are in normal, high speed or in transition between the two. It reflects the dynamic airflow RPM settings ie. when you are in high speed mode you are on MAF only.

[mowton]

Thank you Chris

I was looking to be able to tell in a log whether VE air calc was being utilized. I guess I will set a PID/Hist based on MAP/TPS.

[Chris@HPTuners]

in Normal mode, the dynamic airflow is used (a blend of MAF/VE) in High Speed, MAF only is used.

The other PID to log is MAF Sensor State, if you have anothing other than "No Fail" showing there the airflow is calculated using VE only.

Chris...

[mowton]

in Normal mode, the dynamic airflow is used (a blend of MAF/VE) in High Speed, MAF only is used.

The other PID to log is MAF Sensor State, if you have anothing other than "No Fail" showing there the airflow is calculated using VE only.

Chris...

Chris, I may be wrong in thinking that the dynamic calculations was being used to "replace" the steady state value of the MAF during transient conditions as enabled/disabled by Steady State table. Is that what you mean by a blend, or is the VE value used as an "modifier" to the MAF reading?

I was looking to be able to determine if the fueling during a scan was coming from the MAF or VE and comapre that to rich/lean conditions reported by my wideband. Thought it might help determine if MAF and/or VE needed tweaking. Thats assuming that the WB is fast enough to respond to the PCM changes.

Not sure if I am asking the question right.....sorry

Ed M

[Chris@HPTuners]

the dynamic airflow calculations are a quite complex linear predictive filter equation. It tries to predict the future airflow based on the previous airflow, the current airflow, various corrections, MAP & TPS transients, MAF and VE.

It's a complicated blend.

The theory is that at speeds below a certain level (the dynamic airflow RPM's) the transient behavior, or filling and emptying of the manifold as the throttle is opened and closed, is significant and to get a more accurate airflow you need to model the filling/emptying somehow. This is what GM calls dynamic airflow calculation.

At high RPM (high airflows) the transient effect is very minor compared to the total flow. In this mode "High Speed" as we have called it, the PCM uses a smoothed (lowpass filtered) MAF signal to determin airflow and disables the dynamic airflow calculations.

Are you working on LS1 or E38 controller? The Air Calc Mode PID only exists for later controllers.

I'm not sure what you are referring to regarding steady state, this was only really used in LS1 PCM's to determine if there was enough transient (MAP) occuring to enable the dynamic airflow calculation.

[mowton]

I see now. Thank you for your patience. My car is a 2004 C5 and that is where I saw the Steady State tables. Besides the LS1 PCM's, I have seen alot of E38's, one E67 and a few E40's at my friends shop. I give him a hand when he gets busy.

Thanks again Chris for taking the time to explain. I really appreciate it.

Ed M

[Asylumwarp]

What does the Air Calc Mode PID tell us?..will it differentiate between MAF and VE calcualtion for air flow? Is it granular enough to tell me difference between dynamic and steady state?

Thanks,

Ed M

Where can i find this pid? or how can i create it? a picture, or a config file would be great. thanks

[5_Liter_Eater]

Its a PID like any other. Under engine/airflow. If you don't see it then it's not available for your PCM.