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Thread: Iacv issues with blow-through setup

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Posts: 1-10 of 26
2011-06-22 23:54:06
Iacv issues with blow-through setup
I am wondering if anyone else who is running a blow through setup has issues with the iacv not lasting very long? I am on my 4th one and I think it just died on me. The only thing I can think of that would cause this would be the positive boost damagaing the valve over time since it normally doesn't see boost. Anyone else have this issue or know what might be causing me to ruin so many iacv's?
2011-06-23 04:54:45
IACV always sees boost. Do you mean MAF?
2011-06-23 07:54:54
Not really, I was blowthrough for over 2 years without issues with the iacv. Always had a perfect idle with a nice lope from the s4 cams. But steady. Buddys nx has been boosted for over 3 years same motor same parts, no idle issues as well.
2011-06-23 08:06:08
my car likes to hunt for idle every now and again. I am not sure what the issue is really. Car bounces on idle when it gets really hot. Not really an issue, but I have suspected the iacv is slowly dying.
2011-06-23 11:20:23
I know the one side of the iacv always sees boost but with blow through both sides are. I am on my 4th one which has lasted about a month and sure enough after doing a couple pulls the idle is all messed up and the CEL is on for the iacv. I tried cleaning it but it still throws a code.
2011-06-23 12:57:11
Yeah, I think you mean maf there. IACV is connected to the AAC that gets air from the intake tube. The AAC is a one way valve that is open or closed to allow air to the iacv when the TB is closed. when the TB is open, the AAC is closed and the IACV does NOT see boost. You have something strange going on with wiring or routing.

2011-06-23 13:14:14
Blow through just means your MAF is on the charge pipes seeing pressure. While draw through means the MAF is on the turbo and only has atmospheric pressure (plus the turbo sucking). This how ever means nothing/does nothing to the IACV.

Mind posting some pictures of your setup?
2011-06-23 15:43:29
I understand the difference between blow though and draw through. I'll get pictures tonight but since the maf is just before the throttle body the inlet hose going to the iacv is after the maf just before the throttle body and the other hose from the iacv goes to the intake manifold. It's on a relocation block because I'm running an o2 induction manifold. Therefore both sides of my iacv see boost from the inlet hose after the maf and from the oulet hose from the manifold.
2011-06-23 16:49:23
Your maf is on the throttle body? Maf needs to be at least 8" away from the TB, otherwise the turbulence from the throttle body will screw up the readings. Second problem is your IACV is now before the throttle body, thus your letting unmetered air escape/get in.

Redo your piping and do it properly:
Throttle body ---- IACV feed ----- MAF ------ BOV (Can be on hot side too) ----- Intercooler ----- Turbo ----- Air Filter
2011-06-23 18:32:29
My setup is exactly the way you explained it.....my maf is about 10" from the throttle body and the iacv feed is between them. I'll post a picture when I get home.
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