SilverSmoke

2002 WS6
90mm NW TB
90mm Fast Intake
ETP Heads and TQII Cam
Etc, etc

IAC Count = 126-130
Idle Desired < Dyn Air by 2g/sec

Right now my IAC counts are pretty high and from what I observe my Idle Desired and Dyn Air do not match by any means. I have moved the IAC Effective area table over by 2 rows and have gotten the Idle Desired to closely match Dyn Air. If I go to far then the Dyn Air becomes higher than the Idle Desired. At cruise the Dyn Air is much higher by 50%, and at higher throttle speeds it is exponentially higher.

I've read numerous posts on lowering the IAC count, and seems for me to get any lower right now on my car I have to drill a small hole in the throttle blade. No room for adjustment on the screw right now. I also understand the concept of the IAC Effective Area table, but do not know what the two rows of numbers correspond to and how they relate to each other when adjusting them.

I know the top row ranges in numbers from 0-120, and the lower row labeled steps ranges from 0-310. I'm not really versed in this area so I have no idea how to adjust this table in the correct area, and also in the correct manner overall (for example, I moved the row over by two to get dyn air and idle desired to closely match at idle around 11g/sec, where on the IAC Effective table this corresponds to I have no idea, and no idea what to adjust above this to get the two numbers to closely match).

Would appreciate any guidance on how to do all the above as I'm pretty much lost.

Thanks!

ctd

iTrader: (1)

I've not tuned your style of TB, both my vehicles are DBW. Drilling a DBW is pretty much useless as the computer will just continue to close the blade. Yours is different, so in some conditions drilling the blade or other things can be done to make it work.

Here is a link from HPT that may help with your questions as well provide some different tuning idea's. I think your are on the right track trying match your idle desired airflow to the dynamic airflow. Hopefully this link helps!

http://www.hptuners.com/forum/showthread.php?t=31442

jimmyblue

iTrader: (11)

IAC has a lot more remaining range. I wouldn't be
concerned about counts in the range you say.

What the idle desires airflow discrepancy from desired
means, is just that RPM is met with a very different
real airflow than what you guessed. That's what
desired idle airflow is, a guess; the RPM loop has the
final say and trims in to what you want. Presuming
you have enough range of authority.

The only difference between throttle bodies that
use a GM IAC plunger, would be the channel in the
casting and how it chokes flow at higher IAC position
off seat. That could want the channel hogged out
to match the stock casting, which seems not to
limit flow up to full counts. At low counts the plunger
is what sets flow and the table is unlikely to need
messing, there, unless you have a really small
channel cross-section.

SilverSmoke

Ok, I did the trick of using the TB screw and increased up to 0.65v and reset the IAC by unplugging and plugging back in after turning the ignition on without starting. IAC ounts are now in range of 55-65.

Had to move the IAC effective area over a few more cells and fix the RAF in HPT. Now have to figure out how to balance the rest of the IAC effective area table.