steve40th

I have been fighting via tuning, an idle problem. Basically I thought due to my camshaft (xe 230/236) it was just causing reversion and my LT1 just wouldnt idle till warm. Also, people reading my logs were saying you have an exhaust leak or a vacuum leak. I chased that forever. So, I wasnt able to run AC in gear at idle, and warm ups were a little tearful due to richness burning my eyes.
According to Data logging, the IAC was working. Wrong, the PCM was working telling the IAC what do do, but it wasnt.
So, I was looking at open loop tune etc for the idle which allot of people do with larger cams.
But I came across this little photo.
http://shbox.com/1/iac2.jpg
Never thought the IAC was bad per sey, because I was expecting a code, which now I know there is none for IAC in the FSM. Just a resistance check. Well I checked mine, AtoB was bad. Bought a new one and WOW it idles on its own immediately, and even allows AC in gear (Kinda lopey, but the IAC is doing what it can to help idle).
So, lessons learned here guys. Just because you dont have a code, doesnt mean you dont have a problem.

larryfs

http://forums.corvetteforum.com/show....php?t=1749247

this is my problem....
Mine feels like it has a miss at idle. (when cold)

steve40th

Checking the IAC is a simple check? I wish I had done this along time ago.

rickneworleansla

I have a multimeter but how did you test each wire? Maybe I need to go out and look at it.

Thanks

steve40th

WHat I did was I took the leads from the fluke/multimeter and put them in the iac, where the plug goes in. A/B are the top two(the little tab that guides the plug correctly onto the IAC.) The wires are colored, so A/B will be blue w/white stripe and blue/with black stripe. C/D are light green/white stripe and light green/w black stripe. Look at how the plug goes into the IAC then look at the wires leading into the appropriate port.
Basically they should be in the range of 40-80 OHMS.
I cant find a pic of the IAC itself, but the tab you lift off to unplug it is ontop of AB, and CD are the bottom two you check. Remember, you are checking the resistance between A/B and C/D

JAKE

Thanks for posting that info, Steve.

Jake

MikeC4

Thanks for sharing Steve! Glad you got your Idle back...

Where do you source your parts in Hawaii ?? Do you have to pay out the wazooo ? Just curious in case I am ever lucky enough to live in Hawaii......

Road Agent

Good info thanks Steve!

steve40th

I either do partsamerica.com (checkers out here) or Chris May.
Shipping is deadly. I have had some forum members help me out too.

BlackC6LS3

Thanks Steve...I'll be checking mine soon as my idle is a little weird.

steve40th

Dont forget to reset your IAC if you put a new one.
The IAC doesnt get a DTC code, and I bet allot of problems are associated with it wether it is dirty or broke. The datalogging will show it being told what to do. I wish I had known and researched this a long time ago.

BlackC6LS3

Now you really have my attention. How I do I reset the summabitch?

steve40th

Easy.
You open the throttle sligtly, then start the car for about 5 seconds at above idle, since the throtlle is open it will be.
Then shut it off for at least 10 seconds.
Then restart it let idle and you are done, go drive it like you stole it.

rickneworleansla

How much does a new one cost?

Thanks

steve40th

40-60 dollars. Less than a tank of gas, and worth the frustration of trying to deal with it.

JAKE

96 LT1

My new scanner arrived today and, guess what, it's telling me that the IAC isn't working either; no reading. On top of that, I'm not getting a MAF reading either.

All the other values are showing up real-time and there is no Check Engine code either stored or lit up.

I'll check the resistance of the IAC wiring to see 'what's up'; I just hope it's the same as your 93 because I can't find my Volume 2 FSM.

Jake

JEFNLSA

My hotcammed LT4 doesn't like to idle w/ the a/c on (doesn't stall but idle rpms are down & it hunts) until it is in closed loop. Because of this, really can't leave the a/c in the on position when regularly shutting off & restarting the car. Once you are rolling and car goes into closed loop, kick on the a/c and you're fine...kinda funky.

Sorry for the hijack Steve, this just sort of falls in line w/ what you were initially talking about. Any other cammed LTx's having this issue? Is it common?

FWIW...Due to another idle issue, I recently cleaned the IAC & TB (which worked wonders btw) but that has had zero effect on the a/c situation.

Zix

Just be a man and leave the AC off...that's what I do. Oh wait, that's because my AC isn't working right now.

Anyway, mine will hunt a bit as well with the AC on at idle, but it wasn't quite as bad when I just had heads/cam. How low is your idle going when it's hunting around?

JEFNLSA

Hey Jay.

FWIW, I usually do leave it off but even Bear Grylls (Man vs Wild) would kick on the a/c w/ the temps we've been seeing lately. Plus, many times I have the wife in the car and she ain't playin' the windows down & no a/c game.

To answer your question, my idle is all over the place - between 500 or less & 900 (w/ the a/c on) until she's in closed loop.

Zix

I'd get over to Bills and hook up his scanner, I'd be curious to see what your IAC steps are set at with and without AC. Also, if you haven't been there lately Bills garage has some killer AC going on as well, it's actually nice to go over there and get some work done even in the summer AZ heat!!