98 Civic IACV issues
 

A few problems, so I'll start with the first.

I recently slapped a TD04H on my Civic. Greddy mani and downpipe (got a great deal on them), 480cc injectors, resistor box from a 92 civic. P28 ECU, custom chip from Xenocron to run it until I get it tuned.

At some point during the install, the wires for my IACV got ripped out. Even the pins came out. All I have is the plastic clip. I found a wiring diagram for the wiring harness to run wires straight to the IACV, since we can't find the wires that belong in the IACV. My car was pulsing once it warmed up, with a steady pulse from 1k to 3k. I was told this is because of the missing IACV, thus the wiring efforts. Thats problem 1.

Driving home from work this morning, it was pulsing. I pulled out the ECU adapter harness to start clipping wires. When I went back out to the car, I plugged the ECU back in and left the IACV unplugged. When I started it back up, the CEL came on, and its idling steady at 1500 both warm and cold. Wired the IACV, still had the same issue. After it warms up, it has a rhythmic stutter which goes away when the radiator fan kicks on. When the fan kicks back off, the stutter comes back. Adjusting the throttle screw on the side of the TB doesn't change the idle speed.

Whats wrong with my girl?

Bump. I've narrowed it down to either the IACV wires, or the IACV itself. Is there an easy way to figure out which one it is? I've wired it up every way I can imagine, and the CEL is staying on. No one in town will tune it until I get the CEL fixed. Any help is appreciated.

I managed to fix the problem after I found a more detailed wiring diagram. Here's the solution for anyone else having the same problem.

The OBD2 ECU has two or three wires from the IACV, one positive, one negative. The OBD1 ECU only has one IACV wire. I assumed, after looking at the adapter harness, that both wires from the ODB2 harness went into the same wire on the OBD1 harness. This is wrong. Your positive wire runs to the single IACV wire on the ECU in plug A, wire 12. The negative wire runs into the same ground that the injectors all eventually run in to. If anyone else has this problem in the future, wire the positive to plug A pin 12, and just splice the negative into one of the injector ground wires.