I have an H22A in a 98 Civic hatch, running a P13 ECU. I have tried bypassing the IAC and the fast idle thermo valve. Once the car warms up it wont idle to save its life. It surges very badly. I even tried just bypassing the fast idle thermo valve and leaving the IAC connected and it still does it. So I guess my question is people that have done this successfully, what am I doing wrong? Thanks.

 

bump. anyone?

 

as far as I know, you can't bypass the IAC or the fast thermo valve. Its a common symptom when running an H22 + P13 ecu in any hybrid civic or integra. You might want to try a different ecu, perhaps a P72 ecu reprogrogrammed to H22 fuel/timing maps...JDMShit offers this but they're program doesn't operate disables H22 IAB's.

 

i have the IAB's disconnected anyways. So controlling them doesnt mean anything to me. What about a chipped P28? I can get ahold of P28s where I am at very easily for cheap. So the question is will the P28 idle correctly without the IAC and the thermo valve coolant lines being bypassed. thanks.

 

All 1988+ hondas have a IAC. Later models have a 3-wire IAC that controls the cold start RPM (read: no fast idle valve). A stock ECU MUST have a IAC to idle right. As for the fast idle, the ECU needs that to warm the motor up. If it does not have it, it will not idle right because of the pre-set maps on the ecu are writing with use of the fast idle.

 

well how do people that do the DIY ITBs get away with not having them and their car idling correctly on honda ecus with just a VAFC?