what is requested airflow?

[ozorowsky]

In idle scanning, what is desired airflow or whatever it's called. It seems to me the desired airflow is SAME as RAF (Airflow per ECT). Is this true? Any idle tuning tips? I'm trying to understand all the ins and outs of idle tuning, thanks.

[Chris@HPTuners]

Idle desired airflow is the desired amount of airflow the PCM is commanding to maintain the idle. It is then converted into an effective area (corss sectional area) and then finally converted into either IAC steps or ETC %.

The base running airfow (RAF) is the base airflow value used in the desired idle airflow calculation.

its all in the help file.

[ozorowsky]

Thank you chris, sorry to be dumb. Just was messing with it, and when I change my RAF, seems my desired idle airflow is always same as what my raf is. I'm running mafless right now, dunno if that makes a difference.

[JimMueller]

Idle desired airflow is the desired amount of airflow the PCM is commanding to maintain the idle. It is then converted into an effective area (corss sectional area) and then finally converted into either IAC steps or ETC %.

The base running airfow (RAF) is the base airflow value used in the desired idle airflow calculation.

its all in the help file.

So is it possible to create a custom histogram to properly fill in the effective area table, instead of randomly shifting the values left/right? If yes, a little help If not, how do we properly populate this table?

[Chris@HPTuners]

the only way to calibrate the effective area table is to put the TB on a flow bench and step out the stepper motor, if you haven't change the IAC then the steps vs. effective area table doesn't need modding.

[S2H]

one thing that has worked ok for calculating effective area is just simple math and knowing your TB....
stock 75mm
85mm - multiply table by 1.28
90 mm - multiply table by 1.44
its not exact as this cant account for any shape differences...
but it is by math using area of a circle Pi*Radius squared
and it gets you close enough to move over to the Idle RAF tables next

[JimMueller]

So the need to modify this table for a ported/epoxied TB is just hype? The table would be the same for a stock 75mm TB, regardless if it's a truck or F-body version, or if it's a ported/epoxied version of either?

[S2H]

the need IMO is minimal.
you can usually correct any problems that might occur from a Ported TB just by doing the RAF tables

[JimMueller]

Cool, as I've already recalibrated my RAF and I didn't really want to mess with this table ;D

[Chris@HPTuners]

yes, it only calibrates the IAC pathway. The RAF and other airfow numbers are the way to command more or less idle air.