Idle hunting and shut-off after rebuild

[urhstry]

I just rebuilt my 87 with a .020 bore, Champion irons and ported intake and my perfect idle is no longer. The only thing that helped was to baseline the idle screw but I must have it turned pretty far. How much more air will I be flowing at idle so I know just how far i can go with the idle screw? I didn't think it was going to help at all but it did. Right now if you are driving it or in park and you mash the throttle and leave up, it shuts off. Happens even if you aren't really into it. In fact, at less than half throttle it shuts off if you leave off of it. Any ideas? TPS is at .42 and MAF is 7 at idle. Thanks guys.

 

[SHADOWII]

Have you checked

the tps to see if there are any flat spots in the travel? MAF sensor, gentle tap? IAC? Vacuum leaks?

 

[urhstry]

Yes all the basics have been covered. If the IAC is working correctly, then for some reason the car just isn't getting the air needed when the throttle blade closes.

 

[TurboBuickSix]

I believe he wants your IAC counts from DS

 

[Mad_Trbo]

Did you change your cam?

And are you sure you have all vacum leaks covered, sounds like a leak to me unless your IAC is failing. You run a test against it.

 

[SHADOWII]

Is it possible

that something may have fallen into the iac port thru the tb when it was off the engine and it's blocking the flow of air? A carbon build up in the same? a pinched wire on the iac harness? a bad or dirty pin in the iac connector? Good ground connections? bad iac?
did you remove the iac block and reinstall w/rtv? try removing the iac and reconnecting the connecter, have someone turn on the key while you watch to see if it adjusts? It sure would be a lot easier to barrow one if there is someone close by willing. :smile:

 

[Rosewood T-Type]

The idle is controlled by your chip. making changes with the screw is only bypassing your iac. I'll bet your iac#'s are at zero.If you unplug iac does it make any difference? If not you should follow iac cleaning procedures on gn/ttype. Or just replace it they are not expensive.
Hope this helps.