I just got a BBK 58mm TB and slapped her on the car tonight. I need to modify the IAC to give it more air but you can't really just drill out the passage on this TB like you can the stocker, because of the way its made. I thought i remember there was another method to help lower the IAC count. I did a search and found some talk about it but all the links were too old and didn't work. Anyone know about it. Thanks Mike

 

http://para.noid.org/~lj/PCM%20Tutor...litBLMinfo.htm

This one should help. Very easy mod to do.

 

TTT, that is the mod for split blms but isn't there one for fixing the IAC count maxing out at idle on a aftermarket tb.

 

i know i can adjust the throttle blades to be open more but i'm not sure i want to do that. I like having my idle at 875ish and then if i have to bump my idle up more to help out the IAC i won't be able to hear the cam. For some reason i thought there was another mod to help this out.

 

I found out the mod and i thought i would post since was familiar with this mod. Its only needed if you have aftermarket tb's and you can't drill out the IAC. I have a BBK 58mm Tb that couldn't be drilled on the IAC for more air flow. So here is the mod. You drill a hole in the Intake elbow anywhere after the MAF and install a vaccum fitting. I used a 3/16" vaccum fitting in my elbow. Then run a vaccum hose from any vaccum port off the intake over to the Elbow and connect it to the vaccum fitting. That way you get extra air into the intake but this way its read by the MAF. Its essentially the same thing as making the IAC passage bigger. The important thing is to not make the hole to big to start with or you'll make your IAC worthless. If anyone has any questions just ask.

 

Very interesting. So all the vacuum ports feed into the IAC passages and not the open plenum? I hadn't noticed that. Drilling the hole in my stock TB was a big help for idle manors with my cam...but that went away with my new AS&M TB. Will this feed all the cylinders? Thanks for posting this.

 

The vaccum ports are connected into the entire intake manifold. By unhooking a vaccum port you would actually be making a vaccum leak because you would be having unmetered air entering your intake to be burned, but by drilling a hole and running vaccum line from the intake into the elbow after your MAF the air is accounted for by the MAF. So it isn't a vaccum leak.

 

Thanks, I realize it isn't a vacuum leak the way you did it. I was just wondering if a vacuum port on one side of the manifold would feed the cylinders on the other side of the engine very well through the IAC passages. I don't think I've ever seen a drawing/schematic of how those passages run in the manifold.