Ok, I'm swapping a fully ported Crossfire Injection setup into my 91' RS 305 TBI. My question concerns the IAC setup. I am running this with my orignial TBI computer, so I need a way to fool it into thinking it has only one IAC when I now have 2 since each CFI TB has one. How do I split the signal so that each one only opens half of what the computer inputs. This is what I need to do right?

 

First off, why? I think that the IAC valve doesn't open partially, it has a duty cycle, kinda like an injector, where it opens and closes rapidly, allowing air past it. You might be able to make it work with a bunch of custom programming. Good luck.

 

The IAC valve uses a stepper motor. If the impedance of two coils wired in parallel is not too low, you may be able to wire both coils of the two IAC valves in parallel & have the '91 TBI ECM drive them both. How are they conected in the '82, '83 system? Are they driven by separate outputs (8 I/Os) from the ECM, or are they paralleled & driven from one output (4 I/Os)? To connect the two IACs in parallel, connect each of the 4 IAC wires together (like colors together), and then connect those 4 wires to the 4 ECM outputs.

 

I've heard wiring them in parallel will work fine, just wanted to make sure. Painless wiring makes a adapter that does the same thing, I'm just too cheap to pay for it. So if I wire them in parallel, each valve will open half of the full amount?

 

The valves will open whatever amount is required to attain the idle rpm programmed in the PROM. Both valves will open the same number of steps, whatever that number is.

 

So this will work just fine, they only open as much as the engine needs. Cool. I plan to just get 4 pin connector from the junkyard or Next Gen and make a little harness so I can just plug it in and not have to go the trouble of modding another stock harness.

 

Pep Boys sells the IAC connectors, as well.