[Gmecm] TBI and EFE

[Rick McLeod]

It appears the onset of the 'problem' was coincident w/ the work on the IAC valve. I'd suggest going back to that point and checking the re-assembly to ensure you have'nt compromised that part. Also, is there a base idle setup for the TBI similar to those on TPI, where you bottom out the IAC and then set minimum idle on the butterfly? The purpose of the IAC is not to control minimum idle speed, it's to control thngs like adding when in gear, AC on, and stall prevention when lifting the accel pedal. It's therefore crucial that the mininmum idle be setup correctly w/ the butterfly and the IAC bottomed out, and if there is icing on the butterfly that will affect setting minimum idle, but when running w/ the exception of other issues if the butterfly idle passage gets iced the computer and IAC should compensate by opening IAC to hunt for target idle speed. The surging I suspect is due to minimum idle being set too low or there being a leak somewhere in the idle circuit, or a
 'leaking' injector causing problems.
As for damaging the IAC, I have done what I think you described w/ cleaner on IACs before w/ no ill effects. I'd be more critical of having possibly damaging it by either bending it or getting something in the shaft passage that might have bound it up.
As for the rough idle you refer to, is that w/ the computer disabled from idle control, or with it all buttoned up?
I know my TPIs don't idle really smooth during the setup process, but not to the description you give.
If it is after setup and put back together, I'd have to suggest something else got disturbed during the process that you'd didn't notice.
Since you've worked on all the areas mentioned above, it sounds like going back through all the previously touched areas is in order, making sure everything is clean and not leaking or blocked. Hope this helps, and also hope you've a garage to work in during your artic blast.

BTW, we're about 20*F here in the KC area w/ about 50% humidity overnight, so enjoy your balmy Houston weather! 

Good luck, and btw thanks for the comments on my TBI conversion project, which I'm about 1/2 way through gathering all the goodies for, and your comments have helped steer that effort along.

cheers -rick