P72 (IAB control) not needed for the H23?

[M2Prelude]

I am planning on purchasing an s200 soon, and juicing (adding NOS) my car. I was familiarizing myself with the intake system on my 5-speed 92 Si lude, and in the service manual it is showing that the H23 motors have the IAB also. I went out to my car, and sure enough, there is a vacuum controlled butterly on the drivers side of the intake. I am needing help on which ECU to get.

Why does the application guide not annotate footnote #4 as to needing the p72 to retain IAB control. Is the way that the H23 is wired, such a way that other circuitry (as on a P28) can operate this? Please someone explain why the IAB on the H23 does not require P72.

The main answer I want is: Will the P28 ECU control the IAB on the H23 without modification (other than socketing and adding the s200).

If no (requires modification), then does it matter if the P28 came out of an auto or manual tranny. (I read that when modding to add IAB control, you use some of the auto-tranny circuitry)

thanks for the help.

[DaX]

Will the P28 ECU control the IAB on the H23 without modification (other than socketing and adding the s200).

If no (requires modification), then does it matter if the P28 came out of an auto or manual tranny. (I read that when modding to add IAB control, you use some of the auto-tranny circuitry)

thanks for the help.

No.

does it matter if the P28 came out of an auto or manual tranny. (I read that when modding to add IAB control, you use some of the auto-tranny circuitry).

No. The P28 can be converted between auto and manual by moving a jumper on the PCB. The auto transmission circuitry is already on the board.

[M2Prelude]

Thanks for the help! It would be nice if the Hondata staff could update that on the application list as the H23A needing a ECU with IAB control. (either the P72 as the H22A states, or the recently discovered modding for IAB capability).

I have found in the s200 install manual (Word Document) where you can convert a auto to manual. I have also found some vague instructions in the wiki how to add IAB to the P28.

Now, all I have to do is keep an eye on eBay and local salvage yards for a P28 at a good price!

[RMS]

iab uses one of the auto lock-up output pins, but the circuitry is seperate (except for high side output for obdII conversions)