Another IAC/Idle question

[Spooled]

I finally have started tuning on the T-72'd SBC. I've got it going pretty good now. I just have a few idle/IAC questions. I've read all the previous posts about it and still don't really understand. My idle is higher than I've specified in the idle menu. I've specified about 900 and it's around 1100. At idle, my TPS is 18. So i set the max idle TPS to 19. I know i'm suppose to put the throttle follower all the way to the bottom (10) at my idle TPS percentage. Then adjust my throttle blades until i see 20-30 counts at the IAC TARGET. So i put the TF graph down to the lowest at 18% TPS (which is 10 counts) and that's what the IAC TARGET reads is 10. I tried opening the throttle blades up some but the target doesn't change. The only way I can get it to go up is by moving the throttle follower up a little (to 20-30). Should i CLOSE the throttle blades after i zero out the throttle follower? Will this make the target go up? Maybe I just answered my own question. I can't try it till tomorrow night so I'll go ahead and post this. I'll stop talking to myself now Thanks for any help!!!

 

[bobc455]

If your idle is too high, then air is getting into the motor somehow.

Check-
- vaccum leaks
- Throttle blade position

...and if those don't work, put your thumb over the IAC hole and see if it is closed when it is supposed to be (i.e. it's not wired wrong or something).

(remember that an IAC target of 10 means it should essentially be closed- if the throttle is letting air in, then the ECU won't need to open the IAC. If you choke all other air from the motor, by closing the throttle blades for example, then the ECU will see the RPM's drop below the minimum RPM and open the IAC to compensate.)

I think you'll find that as you close the throttle blades, the IAC target will eventually move.

-Bob Cunningham
bobc@gnttype.org