typeeg

Ok here's the deal. My car runs fine nothing wrong with it but in the morning when I start her up it idles ok. When I start driving it and get to a red light (engine is still cold btw), the idle sometimes dips to 100rpm and almost stall out.. and sometimes it actually does stall. If I tap the gas while i'm in neutral at red lights it revs up and then dips all the way down to 100rpm as well... This only happens when the motor is cold.. once it is at normal operating temp, the problem disapears. I think this could be the IACV because similar problem occured in my old b16a but I can't understand why it only does it when the car is not warmed up. Any suggestions?

typeeg

typeeg

no ideas?

JimBlake

Fast idle thermo valve (FITV). It's job is to raise the idle when the engine's cold. EVERY engine needs something to raise the idle a bit when it's cold.

EE_Chris

So logically, the next questions are:

Do you have a FITV?

If yes, did you do the 'fix'?

If you do have a FITV and did NOT do the fix, then look elsewhere. As the FITV ages, it actually allows more air to bypass it increasing the idle - cold or hot.

typeeg

I have an obd2 gsr motor that is running as obd0 in my 91 civic hatch. I know the later model gsr motors have the fitv.. but I can't seem to locate it on my motor... it is under the throttle body? Is it possible that because my ecu does not read this device that the previous owner took it off? What are my choices in this case?

typeeg

Ok I have decided my problem is the lack of a FITV.. because I have an obd2 motor into an obd0 ecu car... the ecu is looking for the FITV but since there is nothing there for it to use to regulate the cold temp idle.. it is stalling out and having a low idle issue..

so my next question is..

If I do get a FITV from an obd0 motor... where does what plug into since I currently don't have anything there for the FITV to fit into.

JimBlake

OK, what engine, what ECU, etc...

I believe the FITV is not connected to the ECU at all. It only has coolant flowing thru it to warm it up so it closes. Sometimes the job of the FITV is 'built into' the AICV, then there isn't a separate FITV.

I'm kinda guessing, but your ECU would 'know' whether it's proper engine is equipped with an FITV or not. So it may control the AICV differently. So even though the FITV isn't connected to the ECU, it sorta matters whether it's there or not. Does that make any sense? Anybody know whether it works that way?