Something is not right here. The min idle screw is just making contact with throttle shaft and it's allowing you 500 rpm in drive?? With the TB blades fully closed, you should be stalling out unless the IAC is still allowing air through it. Did you jumper "A" and "B" on the ALDL, turn on IGN, wait 30 seconds, unplug IAC and then start motor so you could adjust your min idle ??

 

Get the assistant out there forgot if yours is auto tranny, couple guys told me awhile back when setting the timing on an auto to do it in drive-new one on me.You did change the fuel filter right? Most of my family and friends say I need a hearing aid-prolly right but I sure can hear my FP prime. Doesn't take long to go closed loop, just need to run it a bit and get operating temps up.

 

Sure did, and i wait 60 seconds to be sure. I can hear a ticking from the IAC when I disconnect it.
The only place i may be cheating is that the jumper i use to jump 'A' to 'B' on my ALDL is my code reader. (little black box that slips on the ALDL)
That's all it is really is a jumper, right.
I could take the screw right out and the idle would sit around 500.
The other thing I notice is that the small tab that butts up against the screw can not move all the way back to where the screw dissapears into it's hole. I would say it stops moving about 1/8th of an inch before the screw hole.
Maybe I need to clean the spring it is all graphited up from a sticking throttle body problem years ago. This may be limiting it's range of motion.
Thanks

 

It's an auto and I did it in drive with the parking brake on.

The assistant seems to like to car a lot more when she gets to ride in it.
Come to think of it, so do I.

No I didn't change the filter.
I hear it's a couple of hour job and I didn't have that much time.

I've got a bunch of other jobs with the car waiting to get done. I'll likely get the filter changed when I'm under the car changing some bolts on my cat, swapping the O2 sensor, putting new dust boots on my ball joints and trying to figure out why my tranny is shifting when I don't want it to.
Once that is done it's time to move into the car where I need to adjust my heater core cover and control linkage plus figure out where the parts go that I have left over after changing the heater core.

 

If your IAC is fully closed and your TB blades are fully closed, how can you substain 500 rpm in drive. There has to be air getting in somewhere.
The tab from throttle shaft will not contact the TB where the adjustment screw is because the TB blades have already bottomed out in the bore. Pull the boot off the TB and look inside to see if the blades are actually bottomed out.
An unlit propane torch may help you find where this mystery air is entering.

 

Your welcome, it just doesn't exactly sound like you are getting the results, for some reason. I don't like to assume, because of other variables that can add to your idle issues. If we were to consider valve lash, and timing corrected this would be a good to place to look.
I would also look at the MAF values, I believe tequila boy gave you some reference numbers.
The number used in counts (sometimes refered to as steps) should be approximate, and if I remember correctly should be stated in your helms.
Mine is slightly diffrent, my target idle (825 rpms) has been changed (in the chip) due to mods on the motor. So on mine that number is different, the approximate that I shoot for is 40 counts.
As you tighten or loosen the min. air screw it will change the counts (ie. tightening raises the number and vice versa). The number of counts on a stock motor using a scanner will need to be verified if you choose this method.
When mine was totally stock I found it was not as critical and was able to get a good result w/out the scanner just by using the std. method of adjustment (and a external tach.).
Because of some of the things you mention in the idle characteristics leads me to believe it may be out of range of the computer. Again, this is also taking into consideration that your timing, and valve lash, etc. has been corrected.

 

What your saying does make sense to me.
Throttle blades are bottoming out, that is what I figured was happening.
Air must be getting in from somewhere.....
I don't have a propane torch, they can't be too much $ to buy.
When the unlit propane enters, the idle will increase right?
How much air do you think we are talking about? A pinhole or more?
I only cleaned the IAC portion of my throttle body because I didnt't want the sticking throttle to come back. Looks like it's time to clean the entire throttle body and go from there.
Thanks

 

Does your year have that little vaccum line on bottom of TB (drivers side), and is it connected ? I think unmetered air is entering somewhere or you IAC is not really closed.

 

Thanks again Mseven, I am fairly confident that my valve lash is correct. I have done it 3 times now so I'm happy leaving it alone.
The timing I wasn't happy with until last night. It was the first time I could set it with the car running on it's own. It is at the stock 6*.
I don't have my scan with me at work or my FSM but I will compare the data with what tequilaboy gave me.
What is an external tach worth and where do you hook it up, just to the distributor?

Agent 86 may be on to something.

 

I've used propane alot of times, just a BB bottle with-of course an unlit torch head, I've also used WD40, and yes idle will increase. I wouldn't worry so much about an external tach as I would about getting it to start and idle smoothly, even with our poor hearing we should be able to hear that.

 

Yes that vacuum line under the TB is hooked up.
How do I tell if the IAC is not fully closed?
I suppose setting it and taking the TB off would work.
I have also checked my Boot between the MAF and TB pretty closely and don't see any leaks there either.

 

I have WD40, I'll try it first all around my TB from the MAF to the Plennum.

 

When trying to help someone it is best not to say there is any one possible cause, too many variables that we can't see.
Doesn't your scanner give you tach input? Anything an old tach/dwell might work and I would trsu it more than the dash.
Agent 86 is, and it took me too long too type I am still in the camp of IAC not closed. I still think the procedure is being mooted, another reason to verify where you are at with your scanner. I also think it would have to be a reasonable vac. leak to sustain 500 rpm. w/screw totally turned out. 86 is absolutely correct, if the TB blades were shut no AIR.

 

Leave it on, get the car into closed loop re-peat procedure
I believe he was refering to you looking in there to see if the Tblades are actually closed

 

I knew something was wrong when i was doing it but the car was actually running on it's own which it would not do the day before.

My scanner is my laptop. The rpm pick up is the cigarete lighter.
Seems to work should I trust it's accuracy/

So it's either a substancial vacuum leak or my TB blades are not closed or my IAC pintle is not closed.
I have tripple checked my vacuum line routing. If I had a couple of lines reversed would this happen?
Thanks

 

I knew what he meant, I was just adding other places i had looked.

I won't be able to check into any of this until I get home from work around 5:30.

I took it for a spin last night in the rain and couldn't get the tires to break free from a 20-40 mph roll. Would this possible vacuum leak take power away as well?
Thanks

 

I would trust that more than the dash for rpm, it should be what the ECM "sees"
I agree with one or the other I "think" IAC. but a vac leak would certainly do it.
As long as nothing was sucking air it shouldn't, take one thing at a time , look for all hoses to be connected, take time in IAC/min. air adj.
some additonal reading; see posts by suncr, mike etc. on the subject http://forums.corvetteforum.com/forumdisplay.php?f=48

 

When you check for vac leaks make sure you check all around the MAF too. Glad you quit smoking-but you could have used it to check for leaks as well. DON'T START again-ask me how I know. Good luck.

 

I'm not sure where that link was supposed to take me Mseven.
I didn't see what you were trying to show me.

I'll reset everything from scratch again.
I'll make sure the car is running in closed loop first.
I'll know it's in closed loop by watching it on my laptop wich is where I'll watch the rpms as well.
I'm going to try and pinpoint how any extra air is getting into the TB.
I'll pick up a propane torch. seems like it should work better than WD40 and should make less of a mess too.
I always wanted a propane torch, now I have an excuse to get one.

No smoking for me, this time I'm done. Rick, sounds like you have battled it or are battling the cigarette demons as well.
I wanted a smoke pretty bad a few times this week while working on my car. I think working on my car was the best thing though to keep my mind off the cigarettes.
The assistant quit at the same time too. She is a super nice person but for the first couple of days this week I was better in the garage with her in the house.

I better get back to work. I keep expecting to see a post from my boss. Good thing he doesn't have a corvette.

 

BIG AIR LEAK ALERT!!!!!!!

I found the problem. I'm praying there's only one problem.
Maybe I should say I found a problem.
Drivers side runner where the cold start injector is.
I can't tell exactly weather it's the runner or the cold start tube but the leak was so big that when I tightened it up a little it started whistling. It was silent before i touched it.
Problem now is I'm afraid to tighten the torx bolts for the runners much more for fear of stripping the intake manifold or breaking the bolt.

Tell me to crank on it and I will.

I'm having a very big beer now and will have another look later.
My weekend has just started and even though I have not fixed my problem I feel pretty good because at least now I think I know what it is.
Add to that all my knew knowledge of idle speed, IAC valves and the TPS and has been a good week.

Any tips on how to correct this would be greatly appreciated. Other than just cranking on the bolts.