98 Civic EX MT D16Y8 with a Skunk2 Pro intake manifold and Pro throttle body. Engine is otherwise stock other than exhaust, clutch, flywheel and filter. Set up for endurance racing and is not street legal.

With the iacv connected to the computer, the idle will surge. Acceleration is slow and it starts to run hotter than normal (lean condition)?

When we disconnect the iacv from the computer, the idle improves, the temperature returns to normal, but the car has a dead spot in the throttle around 1000-1200rpm and bucks like crazy. Once you rev beyond that is appears fine.

We have performed a smoke leak test and found no vacuum leaks. IACV was removed and cleaned. Gaskets have been checked. Only codes in the computer are for the IACV (when disconnected) and O2 sensor #2 (not present).

Thoughts?

 

Yes, put the stock throttle body back on and see what happens. For a track car, mid-range performance is critically important for "track out" operation... and an oversized throttle body really hurts mid-range performance. Your Skunk2 throttle body is WAY too big for a single-jingle... the stock one is plenty big at 58mm.