87 165 ECM using tunercat and $32B file. specific one i used was the idle speed adder for ac on. originally set for 50 rpm. i raised to 200.

and there was no change. turn AC on and idle still drops. so i'm missing something obvious.

 

iac steps for ac anticipate would be my geuss.

 

As mere speculation, I'd venture someone has steps labeled as RPM, and they are using a x12 or x25 multiplier in there, so your rpm label maybe an error. In that case your just moving the IAC an 8 count and isn't enough to comp for the load. Try increasing the value to say 14 and see what happens.

Try looking at what your IAC steps are before and after, turning it on to make sure you got the right dohiccy <G>.

Often there is a hot start A/C on adder, which might be what you tweaked.

 

it's in the tunercat constant table. specifically says RPM. pic here. but i thought that IAC was what changes. tomorrow i'll see what my IAC is off and on. i may be at my limit and will need to turn the TB idle screw up and readjust the TPS. then go from there.

 

actually that adds 50 rpm as the AC compressor comes on and pahse back to a normal idle speed.

 

There's alot of things that read one way and to some extent make sense. But all is not as it seems.

If the IAC and RPM counts were exact then You'd have to have idle IAC counts in the 60s for things to line up.

 

my point is that if my IAC counts are about maxed out, say 140, then i'd have to adjust my TB up to get the counts down.

 

ok iac count is in the 60s. turn on the ac it goes to 145. keeps same idle 600ish. i may just need to turn the idle screw up to 700. or should i change my target idle.

 

at 180* temp the IAC counts are 0. turn on AC and it goes to 145. idle 650. i'm going to bring the closed loop target IAC rpm vs coolant to 750. it's at 600 now.

 

Yes, your min air setting is off.
Typically, folks run 0-15 IAC at idle.

Then you might double check the TPS voltage at idle, and WOT to see where you are.

 

the idle screw is set too low. so i turned it up. now it's fine. the TPS is .58 at idle and 4.60 at WOT.

 

a few things come to mind. dirty.clogged.blocked IAC passage. BAD IAC. incorect IAC with incorect pintle. however at 145steps the thing should be at like 2200rpm no load in p-n.

id check the IAC and the IAC passages. i had similar issue when i first converted my honda Cold air bypass into a IAC housing. it took me a while to figure out why it would idle with 160 steps. until i found the pintle head was the wrong shape and the housing had a clog in it. oncei did that i got it to idle with a nice steady 5-10 steps in every weather and with the a/c on it holds it at 45 steps.

 

brand new IAC housing (about 6 months old). new IAC (same age). but i'll keep playing with it. with the idle turned up i'm back into a lean condition at idle. need to play with the MAF tabe 1 again.

 

check for incorrect gaskets blocking things off

 

All's I have to say is "Man, you should see what I did with my IAC..."

On a 383, it will control idle RPM from 700 to 1800rpm. Holds tight around 800rpm at ca. 10 counts, and that's what it seems to like. Tried the adder for A/C, that helps too. Gotta have a good clean bore to pass the air. Mine's a little different and required some port work (yes, on the IAC passage).

What is nice is to have the 'Neutral' setting a little higher and that way when it drops into gear it's right where you want, no stumble. That's on an auto anyhow.

Keep in mind that the little IAC valve takes a second to react and what not, so it has to track what you ask of it. Dynamics in that.