bossco302

Ok i was working on finding the cause of my high idle i pulled my intake tube and was looking to see if my butterfly was closing all the way it is hu?? then ya know the little hole in the middle of the butterfly i put my finger over it and idle droped so i placed a piece of tape over it temp, only dont freak...i let it run for about two min. idles perfect rev it up drops right back down to 800 rpm when i let of the gas. i dont get it.. so this tells me that its idling high because of to much air and to think that some one told me that high idle means to much fuel? i dont think so no more. here is what i might do 1 place a screw and nut in that hole with red loctite or i even heard of just placing a solid gasket between the iac valve hu? does idle perfect with it unpluged. what u all think do any of u have this problem using the bbk 75 mm tb on a 87 sd motor??

SpooledupRacing

I think u need to just adjust the idle set screw..

Dave

50mikey

^^ agreed!

How clean is the IAC?

bossco302

iac spotless just did it two days ago, there is no idle set screw.think about it if there was there would be no iac on the 5.0 efi,the screw is to set the butterfly from sticking per bbk idle is per the puter and iac responds to its demand.

frop

There still needs to be an idle screw, all the IAC does is allow air to bypass the throttle blade.

50mikey

I have an Idle screw on mine...

7upedition

check out www.muscularmustangs.com tech article on idle issues that covers all the potential problems ... i's leave the butterfly alone.. its an adjustment issue... also just for sh*t and giggles check your timing and fuel pressure

gspfunk

What mods do you have? YOu probably have too much TB for your setup. Adjusting the idle screw should help it.

bossco302

sorry the screw just lightly touchs the arm to keep the butterfly from binding the iac is clean the tps is set timiming perfect also. i have a 65 mm tb for some dumb reason i thought it was bigger?? i have a bbk fuel gauge it reads 30 psi wich is correct for idle but i just had a brain storm there is some serious sucktion the tb pulls in. i pulled the return spring and tb cable to cheack action of the butter fly and man the engine pulls som serious vac hard to pull butterfly open. well not that hard but think about it if the spring in the iac keeps the valve closed untill the litttle electic motor pushs it open for more air right ... well what happens when that spring gets worn from heat and opening and closing over the years?? it gets weak .well the vac from the motor will pull it open with out the little electic motor doing it so how could it countoul the idle??? humit cant. i do remember when i took it apart to clean it i pushed on it to open the valve and clean the seat of the valve and it did not take any force at all to open it i think this is where my problem is what u all think??