I already got the this 94-97, 58mm BBK throttle body on my car and the wanted to adjust this throttle stop screw because the IAC counts are way off right now (it is set to far open).. Can anyone tell me what kind of fastener this stop screw is (nut, hex bolt, allen bolt, phillips or flathead screw)?? ALSO, what size is this fastener exactly? (I can't really see into that hole back there and dont want to just start sticking stuff back in there)

 

It's a hex, I used an allen wrench to adjust mine but I forgot the size.

Mike

 

I use a hex on mine also, but I forget which size. Why not just pull the TB off the car and figure it out??

 

Just use some needle nose pliers to adjust the screw, so you don't have to take the TB off. I adjusted mine with the car running and a scanner plugged in so I could monitor in real time the effect my adjustments had.

 

I just want to try and get the IAC counts to atleast close to where they should be with the throttle closed cuz as of right now it won't idle by itself.. I guess I could play around with it after that to get it more exact.

 

Just out of curiosity, I was wondering could I just disconnect the IAC completely and just use the throttle stop screw as a "idle adjustment screw"? (I already check the TPS with a voltameter and the datamaster datalogging a while back and it appeared to be working perfectly except the fact that the screw was set too far open...) So techinquely if I just unplugged the IAC, wouldn't the ECM just run fuel to the car according to where the TPS % is at based on the voltage just thinking that the throttle is being held there?

 

Good question. I would also like to know the answer to this.

 

If you disconnect the IAC valve, your PCM will lose control of the idle. When you turn on the A/C for example, the PCM uses the IAC to keep the idle where it belongs under the added load of the compressor. Without it, any load on your engine, like the A/C compressor, will slow down the idle.

When you start your car cold, the PCM uses the IAC valve to set a slightly higher idle speed, and then slowly brings it down as the engine warms up. When you open the throttle while driving, the PCM opens the IAC valve farther so that a sudden closing of the throttle blades will not stall the engine. At coast down on closed throttle, the PCM uses the IAC to elevate the idle and keep it higher than the "vehicle stopped" rpm. If you don't care about all these refinements, you could delete the IAC.

What is there about the BBK TB that requires that you remove it to adjust the idle stop screw? The stock TB and the Holley can be adjusted with the TB on the manifold. I borrowed a BBK for a while and don't remember having to take it off the car to adjust the screw. Messing up the threads with a pair of pliers doesn't seem like the right way to do it.

 

There's a couple of problems with doing that. First, you're going to have to make sure that the IAC is completely closed before you disconnect it. The IAC doesn't have any fueling affect on the car, it's only there as a means for the car to maintain the idle the ECM is programmed to hold.

Second, and this is the larger of the two issues, if you try to just use the TB blades as a means of idle air, you're going to run in to an issue of uneven air distribution to each cylinder, and will start to see split fuel trims at idle. The IAC has passages which direct air to each intake runner in the manifold, ensuring each cylinder gets an even distribution of idle air.

I wouldn't recommend taking the IAC out of the picture.

 

What should the IAC's be on a cammed car?

 

the set screw is a #3 metric Allen.....take the throttle body off and turn the set scre around...that way you can adjust it withuout removing it...or you can loosen the throttle cable braket and access it that way