Stumbles off boost, low RPM, idles fine, boosts fine

[AuburnRyan]

Hey all,

s13 SR with FMIC, HKS SSQV, Walboro HKS Actuator, etc. etc.

Car boosts great to 14psi, and idles fine around 1000 RPM.

Car has developed hiccups, stumbles, or bogs briefly when I'm cruising off boost (usually around -10 vac). The vaccum seems to *sometimes* jump when this happens, but it's a quick hiccup when I'm cruising.

First thing I'm thinking is vaccum leak. I just glanced over the lines which look snug.
I recently repaced spark plugs a few weeks ago.
Could my walboro be going out?

Any other ideas?

[AuburnRyan]

*cough*

Is this and odd issue that the problem only occurs off boost?

[the head]

check all piping for leaks I would guess that is your issue, that or the BOV is leaking if all else fails recirc your BOV

[Gearhead_42]

that or the BOV is leaking if all else fails recirc your BOV

I understand (have no personal experience with this) that a free air BOV can cause this kind of stumble. I'm assuming the SSQV is not recirculated? Basically, MAF is telling the car there's more air than is actually getting in, causing a rich condition. Leaking FMIC piping could also be to blame.

And yes, I know I just restated you guys :o

Dan

[AuburnRyan]

I'll tighten the BOV to check, and yes it's open...but I'm talking about a stumble when I'm not boosting, so the BOV shouldn't come into play, right?

It' feels as if the fuel gets cuts for a half second. Like there is air bubbles or something...a quick hiccup, and that's it.