alright the BBC tb was installed and mounted yesterday, the TPS works fine, but i cant get the IAC to even move... so it idled at 2Krpm... i just figured my blade were stock open cause of the throttle cable, but all of that is fixed... i just can get any response from the IAC... after grounding the AB terminals on the OBD1... so i figure something is wrong..

IAC is the flat style in a row, my old IAC (SBC) was 4 in a square... its of a 89 burban, and my truck is a 95 burban... both color codes are no where alike or the same

the wires on my old IAC indicate.. (SBC) (4 in square)
A=blue / white stripe
B=blue / black stripe
C=green / white stripe
D=green / black stripe


im going to pull the BBC IAC harness to list those wires in a lil while.. but if anyone can help now please do. i already searched the search engine, and its seems to be tons of confusion on this subject... so many different answers its not even funny... for christ sake, can someone list the correct wires...

im not trying to buy a wire harness either, as i just need to know what wire goes where.. my wires are already cut, and ready to solder once i get them working...

 

did you do the "ohm test" to confirm it is not kaput?

 

yea, i got the ohms, both were about the same, if i remember correct 53... but my meter is a old dmm, i dont have my fluke meter here. but the numbers where consistant with the ohms, and i zeroed out the meter to get a ruff estimate of the wires resistance.... so that should be about right, cause it was withing tolerance with my book specs...

i finally got the IAC to respond, with AB jumped... with it plugged up, and out of the tb... while the engine was started, and IAC wired to RBob specs... in a old thread i found..

i just had to draw it out with my own diagram/table...

the IAC extended all the way out, and shot the pintle and spring out.. so I take it this must be wired correct, as my old SBC would do that outside of the TB with the AB jumped...

I need to know do i install the IAC with the pintle fully extended or do i install it with the pintle fully compressed... ?????

here is the wires on the BBC harness for the IAC
A= blk / red stripe
B= yellow / blk stripe
C= purple / white stripe
D= white / purple stripe


here is the wires on the SBC harness for IAC (stock PCM 7747)
A= blue / white stripe
B= blue / blk stripe
C= green / white stripe
D= green / blk stripe


(SBC iac) >> (BBC iac)
D >> C
C >> B
A >> D
B >> A

that is how i got the IAC to fully extended with AB jumped at the OBD1.. and the engine on, IAC plugged in, and out of the TB.. TB was plugged with a old IAC to keep vacuum...

the truck idles low, about 650 rpm, with the EST wire hooked up... so i guess its working correct.. but it wont hold steady, but its not reving to 2k rpm like before...

i take it i just need to tune it now.. but i need to make sure the IAC is working properly... how can i make it compress by itself??? its running rich, but with IAC out and it plugged, it doesnt smoke as much... but with the IAC in, it likes to smoke...

 

Install the IAC with it full in. Don't press the pintle in by hand.

Swap two wires of the same color and do the A/B short. This will run the IAC motor in reverse and you can let it feed the pintle back into place. Then put the wires back.

Once installed run the truck over 35 MPH or so, pull over, shut off engine, count to 10 (about 4-5 seconds), then restart engine. That should reset the IAC. Sometimes it is 45 MPH is the calibration. But give it a try.

RBob.

 

ok dang, i pushed and screwed it in some.. but i used to do that with my SBC iac.. i guess thats bad then... crap i will reverse 2 wires of the same color to get it to contract some, then im going to install it fully extended.. and see what happens.. ill solder them up if that is correct then..
i got to get to dyno quick, im rich as a pig..

thanks Rbob