My car will only start if the IACV is unplugged.

[Jessekrs123]

Okay, after tinkering around with my car yesterday, I noticed that when I unplug the IACV, I can hear my relays clicking, the fuel pump priming and the injectors priming as if I just turned the key to on.

If I try to start my car with the IACV plugged in, I get no spark.

Once I unplug the IACV, the car starts up just fine.

Once I plug the IACV in after the car is started, it idles fine and drives fine, it does not lose spark like I had expected.

I've checked all grounds, they are good, even the grounds in the connectors are grounded.

I'm starting to lean towards a bad ECU because I have had numerous problems with losing spark and I seem to be able to find ways to get it running.

Any suggestions? I am looking for a new ECU so if anyone has one for a 1994 Legacy, preferably one from a car that didn't have ABS, AWD and an automatic transmission, I will be willing to buy.

I have replaced almost everything on this car so... my next step is a new ECU.

[Legacy777]

Sounds like you're on the right track with the ECU. However I'd suggest checking the wiring from the ECU to the IAC valve to make sure it's not shorted or has some oddity. Does the middle wire going to the IAC valve have 12v on it with the key out of the ignition? What about with the key in the "ON" position? What about once the car is started?