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1991 Honda CRX
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Discussion Starter #1
This is a DIY to relocate your IACV/EACV. I needed to relocate it because I have a DOHC ZC with ZCspeed adapter plate and Skunk2 Intake, so firewall space is close to nothing. Maybe you want to clean the bay up a little and give a cleaner look. T1 sells a IACV relocation kit for around $70, I'll show you how to make one for next to nothing. It is a very simple setup, it's a valve that the ECU uses to control idle speed by letting outside air into the engine without touching the throttle.

All you need to do is get a nice piece of metal, or you can use plastic but when you thread the fitting in it might strip out easily. I had some 1/4" 6061 aluminum lying around, you need about 4" x 6". You can get this from a metal place for about $5 if you don't have this lying around. I then ordered a fitting from summit racing, 1/8" NPT male end with 1/4" barb' hose end. You can get a cheap brass one from a plumbing store, but I don't like to mix metals (aluminum plate with aluminum fitting).



First step put the IACV on the plate, leave enough room around the edge (you can trim it later), and mark the bolt holes. What I did was put some paint down the bolt hole and when I take the IACV off the marks are there. Drill them out to what the Then tap the holes, I used 3/8" - 16 tap if I remember correctly and got some bolts to go with it. Trim the bolts so that they don't stick way out the other end. This is when the 1/4" plate helps, because you get more threads than with a 1/8" plate.



Next, test fit the IACV make sure it bolts down nice and tight. Take it off and then put some paint around the gasket, then bolt it down and take it back off, you should get this:

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Now do as the 1/8" NPT tap says, can't remember off the top of my head think it was 5/16" drill size? Drill out the holes in the plate and tap one hole, you can tap both and have two fittings one for the Intake air and one to go into the intake manifold. I just left it open. The intake side of the IACV, usually has a metal screen as a filter or a smaller hole that is how you know.

Last step is to put the fitting, use some loc-tite to keep it from seizing up and keep it tight. You have it done, now just mount it under the intake manifold. I had a empty hole under my intake that I tapped and put a stud into (a stud is better, so you can have a easier time taking it off and putting it on later down the road). Drill a hole for the stud to go through, put the nut on, and then just run a hose from the fitting to the intake manifold. It's that simple. You just need to make a block-off plate for the original holes, you can use thin metal, drill two holes for some bolts and put some sealant on so it doesn't leak. You can run some coolant lines, very easily just shorten the lines already on there. This all cost me just under $10, still wanna spend $70 on T1's stuff?

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1988 CRX
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Interesting... never thought I'd see the need to relocate one of those. +rep for the DIY
 

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1991 Honda CRX
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3,716 Posts
Discussion Starter #3
Interesting... never thought I'd see the need to relocate one of those. +rep for the DIY
You'd be surprised just how common this is. Mostly with alot of the drag car guys running intake manifold that don't have room for a IACV, or the show car guys who want the ultimate tucked/shaved bay.
 

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Very diy rep for you.
 

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Good job man. An easy way to block off the old IACV holes on the manifold is to tap those holes for NPT threads, and buy some NPT plugs. Comes out with a little more clearance. But still, good job!
 

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1991 Honda CRX
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Discussion Starter #11
Good job man. An easy way to block off the old IACV holes on the manifold is to tap those holes for NPT threads, and buy some NPT plugs. Comes out with a little more clearance. But still, good job!
Yeah, I thought about that but plugs would cost me a few dollars, a piece of metal lying around and some sealant is free :bigok:

Thanks everyone, rep'd back.
 

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if i understand this correctly you have the part of the iacv which goes to the whole into the manifold with a fitting, the other part of the iacv is just open to free air, and you have the fitting hooked up to a hose the any hole on the manifold that sucks air in... is this correct?, this actually solves my problem because right now i have a y8 automatic manifold which has no holes in the back for this type of iacv now i can use it by doing this mod... very very nice!
 

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1991 Honda CRX
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Discussion Starter #14
if i understand this correctly you have the part of the iacv which goes to the whole into the manifold with a fitting, the other part of the iacv is just open to free air, and you have the fitting hooked up to a hose the any hole on the manifold that sucks air in... is this correct?, this actually solves my problem because right now i have a y8 automatic manifold which has no holes in the back for this type of iacv now i can use it by doing this mod... very very nice!
Yes, on the IACV there is two ports, one will either be a smaller hole or have a screen on it, it is fresh air (usually comes from the intake air), and the other just has a fitting and hose to the intake, so when the IACV opens the intake manifold under vacuum can suck in more air to help with the idle. Just make sure the fitting and hose is tight or else it will cause problems.
 
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