quick iac step question

[turbo3.4]

does the more iac steps you have mean more air thats flows or does it mean less air? thanks for the help

[Bernard Fife]

turbo3.4,

If you have set the stepper up correctly, more IAC steps in the table means less air (slower idle).

More steps in the 'start value' means more air, if it hasn't hit the stop like it should.

For example, if a start value of 160 opens the valve all the way, then 120 in the IAC step table gives less air, and 120 gives even less air, while 160 should close it completely.

Lance.

[turbo3.4]

ok, so my start value is 250. so say my idle is to high with a step count of of say 120 at whatever temp i should increase the step size to lower the rpm correct?

[Bernard Fife]

my start value is 250. so say my idle is to high with a step count of of say 120 at whatever temp i should increase the step size to lower the rpm correct?

turbo3.4,

Yes.

Lance.

[turbo3.4]

I tested to see if I had it wired correctly and it is. And my idle is still around 2600rpm. My start point is 160, cranking is 100 and changing the temp steps seems to not do anything. What are known good step sizes that work with the GM IAC's??? I've changed my starting point from 250, to 200, to 160 and it seeams to drop around 100 rpm. What would happen if I made the start point around 100 or 75 and the cranking the same?

[mops]

what happens when you close it completly ?

try incerasing the max step count (not sure whether thats possible) , maby your iac does more than 160 steps...

if you are sure it's completly closed then you have vacum leak somewhere... dins and trace that (possibly idle adjustment screw on throttle body.

[turbo3.4]

wel the bigger the starting count the higher the rpm goes. i know its the iac cause when i put my thumb over the iac hole in the TB the rpms drop to around 800. i think i'm going to try a very small starting count and see what that does. i have a 2x58mm LT1 TB on my little 6 cyl so i'm sure the iac doesn't need to be open very far to let the rpms get up there. and the idle screw on the tb is barely touching the plates when closed.

[mops]

as you said. decerase the starting count. you might have your iac wired backwards.......

[turbo3.4]

i pulled out the iac and check to see which way the iac moves when i turn the key to on and it does move to wide open so the wiring is correct. i'm going to play around with the start counts and see whats happens.

[mops]

at least you know that it's wired correctly.

get your idle to where you want it. it's ok the be slightly to moderade rich, however stock setup should idle just fine at stoich... mind you you cant adjust idle properly until your car is fully warmed up.