IR injection idle air control

[philminotti]

I'm curious how idle air control is managed in an IR injection setup.  I use a throttle body/port injection setup on my 482, which has an IAC motor...I found that the IAC is really helpful for tuning the cold start behavior of my engine.  As I'm planning on switching to Jay's IR crossram injection in the future, I got to wondering how idle air control is managed in an IR setup.

Thanks
Phil

[Barry_R]

With either a connected plenum below the manifold, or with a nest of vacuum hoses connected to a common cavity for the IAC to hook to.  A remote IAC with a little filter and you're set.  Or do what most folks do an pitch the IAC & tune the idle like a carb.  You can use the EFI controller to stabilize idle speed by walking the timing back and forth by a couple degrees.

[cammerfe]

Many IR manifolds actually are designed for some sort of line either cast-in or with bosses so as to be able to provide connections between the runners to provide a way of balancing flow.

I had a '72 Pinto with a 2.0 litre engine that I first ran with a mechanical injection set-up. A couple of years later I switched to a pair of 45 DCOE Webers. The manifold could have been used for either TBs or the carbs and had such a provision cast in to provide for balancing flow.

KS

[jayb]

With either a connected plenum below the manifold, or with a nest of vacuum hoses connected to a common cavity for the IAC to hook to.  A remote IAC with a little filter and you're set.  Or do what most folks do an pitch the IAC & tune the idle like a carb.  You can use the EFI controller to stabilize idle speed by walking the timing back and forth by a couple degrees.

Barry is correct, the IAC is usually connected to the vacuum block that the individual vacuum hoses go to in an IR setup.  When the IAC opens it allows air into the engine through the vacuum hoses.

[Dumpling]

Would you need two separate accumulation chambers if you wanted BOTH IAC and a vacuum source for the trans and/or power brakes?

[jayb]

I don't think so, I think you just need a chamber that is large enough to feed the vacuum requirements.