does that mean I'm lean? it stumbles at low rpms. it has been idling high lately in the cold. just assume everything works flawless in the warm weather. it's cold here in michigan now, and I am getting ~13mpg (versus 17 over the summer time) lately.

 

Once you reach operating temperature how does it feel? Have you done anything to it since the season changed?

 

at operating temperature, the idle is significantly lower but it's still high (around 1200, versus 700 in summer). I backed off the timing 2* because i thought this rough running had something to do with that, but it hasnt changed.

 

What t-stat do you have in teh car. Can you hook a scantool/winaldl up and see what its doing?

 

have you checked for vacum leaks??

 

I dont see where it would be leaking from, but I'll check.

 

How well did you get the chip dialed in. I know that you are runing the LT4 cam with vortec heads.

 

I put my finger in the IAC port and it dramatically reduced the idle (even cold) but it would never bog out and stall from doing such. I pulled the weatherpack connector out and the idle didn't seem to change, maybe a little higher at the most. I wadded up a piece of paper and wedged it into the IAC port (it's not air tight, but it does restrict the air flow) then I plugged up all of the vac lines on the TBI except the MAP tube. The car idles around 900 now (cold) and about 500-600 in gear and does not bog out or studder anymore. I don't think there are any vac leaks in the TBI or manifold themselves, but just to be sure I will double check tomorrow. I'm guessing my IAC is stuck open, or at least dirty, even though I just cleaned it a week ago with carb/choke cleaner. The last time I replaced my fuel filter was ~25k ago as well, could this play a similar factor, or have I narrowed it down to a vacuum leak?

 

try closing the throttle by hand. Sounds like the butterflies may be hanging up. Alternatively the paper may be letting air past. You can seat the IAC by jumpering pins A + B with the key on and engine off. Unplug the IAC before taking the paper clip out and it should fully extend.

 

the butterflies are closing all the way but I'll try this later tonight. Jumper pins A and B? which ones, the top two? I dont have my chiltons handy. And please explain that so I dont mess up my electronics :P

 

The top two pins all the way to the right. Give the IAC 10 secs or so to fully seat and pull the connector. Start it up (sans paper clip, of course) and see how it idles. If its still really high then a vacuum leak is a real probability.

 

if not, it will probably stall right?

 

The top two, right hand pins in the ALDL port .

 

I still havent done this