My car is a 1997 I30t.

So this is my issue, I have a code, 0205 Idle Air Control Valve. I purchased a used but working IACV and I still get the 0205 code. I verified that it works by plugging it into the evap purge harness and watching it go up and down while turning ign on and off.

When I plug it into the iacv harness it doesn't go up and down as it should. I also tested the old IACV and it does not go up and down.

I did a continuity test on all of the iacv harness wires back to the ecu and they all check good. I'm getting voltage on the wires that should be getting per the FSM.

At this point all I can think is maybe the ecu is bad. I have heard that swapping to a 1995 ECU might solve most of my issues. Is this true?

evo

Per the FSM, remove the IACV, but keep it plugged in its OWN harness. Then turn the key OFF and ON. The valve should go up and down with the key position.

Why are u using the evap purge harness???

If its not workin in the IACV harness then the valve is faulty.

I bet u got a faulty used IACV. just grab another from the junkyard. Its a step motor, so varying voltages/current make it respond differnetly.

THe evap purge solenoid is just one voltage/current.

Double check the wiring too per FSM. But i think the valve is broken.

Tried this it does not go up and down.
To test if it goes up and down. The evap is also a stepper motor, if not the same stepper motor. If it goes up and down on this harness it should on the other. Plus they work off bits of the same harrness.
Once again if I can get it to go up and down that indicates a working iacv, The original is faulty as it won't actuate on either harness.
Are we talking the same part? The evap canister purge volume control on the top of the intake manifold? It looks identical to the iacv stepper motor and the plug also fit the iacv motor?

evo

Had to look at the FSM.

Yes the Evap purge solenoid is a step motor as well. The test for both IACV and Evap solenoid is the same as well.

Since the IACV works on the Evap harness, then its either:

The harness is messed up
THe valve is messed up
or the ECU is messed up

If the valve is getting power and there is continuity between all terminals per the FSM then the harness is fine. then check the component. The FSM says it should work on its own harness and specify two differnet voltages for the two different components which tells me they work off different voltages.

I still say the used IACV is faulty and try another from the yard.

I really doubt the ECU is busted.

I dont know if you can swap in a 1995, but u shd be able to find a 1997 ECU.