Dynamic airflow trims?
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TECH Senior Member
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From: Long Island, NY
Dynamic airflow trims? If i understand this correctly, dynamic airflow has some sort of a trim that calibrated itself to the MAF readings during steady state operation. How can i look at either the raw dynamic airflow numbers vs. adjusted dynamic airflow, or the trim itself? I have a feeling this is screwing with me and making it difficult to properly adjust the VE.
My understanding is that you can use the dynamic airflow reading to calibrate your MAF after your VE is dialed in. For dialing in VE, the MAF should be diabled using MAF fail = 0 and its readings ignored. There are a couple spreadsheets available to recalculate the MAF table once your VE is set and you log clean MAF & Dynamic Air numbers.
Thread Starter
TECH Senior Member
iTrader: (4)
Joined: Apr 2003
Posts: 6,249
Likes: 3
From: Long Island, NY
Originally Posted by Ragtop 99
My understanding is that you can use the dynamic airflow reading to calibrate your MAF after your VE is dialed in. For dialing in VE, the MAF should be diabled using MAF fail = 0 and its readings ignored. There are a couple spreadsheets available to recalculate the MAF table once your VE is set and you log clean MAF & Dynamic Air numbers.
Here's a snippet from HPTuner's help file that starts to explain it better. Id like to ind a way to see this in action:
Steady State
A critical part of the dynamic airmass calculation is determination of when the engine is operating at a steady state condition or unsteady (transient) state. During steady state the PCM uses a filtered MAF signal as the basis for airmass calculations, the PCM also calculates a "VE Correction Factor" during steady state. The VE correction factor is simply the ratio of the MAF airmass to the VE airmass and is used to "offset" the VE calculated airmass when a transient is encountered.
During unsteady state, the PCM uses the VE table to calculate airmass and it is offset (multiplied) by the last calculated VE Correction factor. As long as the VE Correction factor is within limits it will accurately offset any differences between MAF and VE table airmasses and the transition between steady and unsteady (transient) prediction will be smooth.
