installed intake manifold, car now idles poorly

[niSm095]

Today I swapped out the stock SR intake manifold for a custom made aluminum piece...very good quality. Unfortunately, after we checked and checked all the vaccum sources, wiring, adjusting TPS (q45 throttle body) We still cannot get it to idle correctly. We found that..
the blow off valve is pushing air constantly, pulled the vaccum hose (which runs to a dedicated bung on the manifold) and plugged it...to no avail

it idles high..about 1600 rpms...we tried adjusting the tension on the throttle cable...nothing. when we blip the throttle it revs up and drops, then rises, and drops...continuously.

We sprayed carb cleaner around the ports and throttle body to check for leaks, none present (the IACV and throttle body were put on with red RTV.)

The setup on the car is as follows:
Blacktop SR
2871R
740cc injectors
Enthalpy tune
z32 maf
SAFC as well
...etc

Any suggestions?

[slothonaleash]

adjust the spring on your blowoff valve? or get a new one

also try adjust your IACV if you haven't already done that, it may not be letting enough air through at idle

[hayai_240]

I had a similar issue when I had to replace a gasket on my intake manifold. It turned out that the 2 hoses that ran to the IACV got kinked after I reinstalled it and caused my car to idle at 1500 constantly. After I fixed the kinks, my idle went back to normal. Just double check that the hoses aren't kinked.

[SoguRacing]

or you can try to get a tune done. a bigger throttle body will let more air by the throttle plate than calibrated compared to the stock unit.

[niSm095]

Today I'll check the hoses. try adjusting the idle screw and bov. If this doesn't work we were going to try to richen it up some with the afc. Thanks guys.

If anyone else has suggestions, please chime in.

[niSm095]

so...today...adjusted the BOV. Having a problem with it opening now, should the vacuum source be on the throttle body? or the manifold itself? I'm thinking its not getting enough vacuum to draw it open.

The IACV hoses weren't crimped, but we did adjust it.

With the combination of that, retarding the timing a little and messing with the three throttle adjustments on the q45 tb, we got it to idle pretty civily. I'm guessing since the addition of the manifold and huge throttle body I'm not going to be able to get as smooth an idle as I was before, is that correct?