I am wondering if its possible to make this whole setup work. I am in the middle of fabricating a custom intake manifold and am curious of the challenge it will arise if I bypass the IAC completely along with the Fast Idle Thermo Valve. I am running with an OBD-I ECU. I understand I will obviously not get the car running high rpms on startup.
Basically both ports that feed to the throttle body via the intake manifold must be bypassed in this design. Has anyone ever done this before? If this wouldn’t work, how could I appoach the situation to make it work. Could I modify the Throttle Body etc?
I’m sure there’s gotta be a way to hook everything up so there is no roaming idle. I’d like a car that acts like a car on standalone or carburated. Turn it on, watch it idle at like 800rpm at cold…
How could the ECU make the idle roam if it can’t control the amount of air the engine is getting and only fuel?
I don’t see any performance gains in doing that. In any case, to my knowledge, the FITV and/or the IACV are required to allow extra air during startup…not just idle. I could be wrong in this matter, of course.
I’m using an ITR intake manifold and the FITV I have does not mate correctly to it so it’s not currently hooked up. The car performs fine and the only noticalble time is at- you guessed it- idle especially when you start it up. Just erratic sometimes thats all.
Oz, I don’t know if it was unclear but I’m not doing it because I think I’m gonna gain hp, I’m doing it because I’m making a custom intake manifold…
Anyway, Thanks! [/B]
Richie,
I understood what you wrote. Are you’re telling me that you’re making this custom manifold to perform like stock? :shrug: Just buy another manifold.
IMHO, the main function of the FITV is to speed up the process of engine warmup. Unless you want to wait 20min. on a cold winter day to see your temp needle move 1/2", I don’t see the point of bypassing it. And I really don’t see any other way to control your idle if you bypass the IACV.
I understood what you wrote. Are you’re telling me that you’re making this custom manifold to perform like stock? :shrug: Just buy another manifold.
IMHO, the main function of the FITV is to speed up the process of engine warmup. Unless you want to wait 20min. on a cold winter day to see your temp needle move 1/2", I don’t see the point of bypassing it. And I really don’t see any other way to control your idle if you bypass the IACV.
Regards,
Oz [/B]
yeah teg92 seeing that you live in canada and i live in Texas the benefit of a FITV might be greater to you than it is to me- i didnt even think of that at first
I understood what you wrote. Are you’re telling me that you’re making this custom manifold to perform like stock? :shrug: Just buy another manifold.
IMHO, the main function of the FITV is to speed up the process of engine warmup. Unless you want to wait 20min. on a cold winter day to see your temp needle move 1/2", I don’t see the point of bypassing it. And I really don’t see any other way to control your idle if you bypass the IACV.
Regards,
Oz [/B]
“I don’t see any performance gains in doing that”
You said you didn’t see how I’m gaining performance. Well I am not making the intake manifold so that I can bypass the idle stuff, I am doing it for anothe reason which does improve performance, don’t worry about that department.
I am not going to be driving this car in the winter, so I’m not worried about cold winter starts.
I’ve bypassed the FITV on my LS motor before no problem. Instead of running the coolant line into the inlet of the FITV and the outlet line to the IACV. Just run the line directly to the IACV and leave the FITV there. Or you could remove the valve entirely and leave it like that.
The only difference is the car won’t idle up in the morning for a few minutes to warm the motor up initially. But you can always do that manually by just holding the rpms at 1500rpms for a minute or so if you’d like. Other than that, there are no ill effects.
I’m not sure about bypassing the IACV though. I would think that you would need that for sure.
What exactly is the difference between the two? The manual doesn’t go in depth to explain the roles they both have. TIA [/B]
To my knowledge, the FITV only operates during startup. Notice how the engine high revs it for roughly 30 seconds, and then kinda settles down after? That’s the FITV working. In any other instance, the IACV takes over.
To my knowledge, I second what Oz is saying. But yeah, for racing, you can bypass it. For regular everyday driving and starting your car in the morning, better to have it.
