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IAC questions

Sparkles

New member
Joined
Jun 29, 2017
My standard 940 IAC bracket doesn't fit in the Amazon engine bay so I wanted to double check a couple of things.

Can these Bosch IAC units be orientated upside down, wrong way around etc, and still work?

Is the valve normally open? It'd be great if I could just put a filter on the end that goes to a boost pipe as standard, but I'm guessing I won't be that lucky.

Thanks
 
AFAIK, the IAC can be oriented any way you want and direction of flow doesn't matter. It just passes extra air to provide a good idle. Internally, it's a spring loaded cylinder that rotates depending on how much power is applied. Even if the orientation did change the behavior slightly, the ECU will adjust the applied power to get the proper idle (ahhh, the wonders of a closed-loop control system).

The factory hoses may dip down a bit before the IAC to temporarily catch any condensation, but it should evaporate off once the engine is up to temperature.

Some folks block off the IAC nipple on the manifold and manually adjust the throttle butterfly closed position stop to get a good idle, but the adjustment will be a tradeoff between poor idle when cold and fast idle when warmed up.
 
Orientation doesn't matter AFAIK. There is an arrow on the IAC to indicate direction of flow but as Bobxyz said, I don't see how it matters.

BS_0280140520_Rig.jpg
 
Thanks. I got around to finding a place for the valve to go that means I can use an existing hose to reach the manifold.

Does the other end have to be plumbed in to the intake after the turbo? I've got two valves and I can blow through both of them unrestricted, will the valve just leak boost if I put an air filter on it instead?
 
YES One side goes to the intake and the other goes to the boost pipe or you will have a big boost leak.

Another reason is if you are using a AMM/MAF the IAC has to connect to measured air.
 
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