After I installed the 48mm TBI, my laptop crapped on me so I really didn't get any first hand data. I got WinALDL going again and now I find my IAC counts at idle are around 14! They used to be like 32 and 35.

The vacuum holds fine where it used to at about 33-35 kPa. Could I have a vacuum leak?

I opened the throttle plates a smidge with the adjustment screw and drove around like that for a while (laptop crapped again). Then last night I was on my way home and saw that the IAC counts were 0!!! It idled just fine as always, right at 575 RPM and 33 kPa.

Any thoughts?

 

I like IAC counts around 10 at idle with car fully warmed up.

 

HI ASTRO,
In order to raise your IAC counts you need to close the throttle blades - not open them ,then restart the van you should look for counts close to 20.

 

Yeah I know. The thing is if I close them too far the throttle plates stick in the bore.

Another friend of mine mentioned the throttle shaft bushings may be worn, if there are even bushings in there.

 

remember the bigger TB lets more air in. So with no changes you are gonna have less iac counts.

The lower the better with tbi.

 

V8,

I have the bored tbi units and 20-30 counts seems about right.

 

Just as much personal preference as anything.
Personally I like the ecm having as little control as possible over the system. The IAC count applies also to the AE, and deceleration controls (dash pot effect) also. You'll have more throttle response with lower IAC counts.