Stalling in Neutral

[Subsparx]

So I have a weird issue with my car that has recently cropped up. I installed a JoeP MBC incorrectly a while back (noticed due to the boost reaching 14psi at one point). So I kept it out of boost for roughly a month due to not having time to remedy the issue (lack of time and vacuum hose to reroute the way it was set up). So here's the issue. I never let it get into boost the entire month. I just reinstalled the MBC two nights ago. It *seems* to be working fine. I have it set for roughly 8lbs of boost. When I accelerate hard, it goes exactly to 8, no creeping, spiking nothing. However, my idle has become EXTREMELY choppy, and when I shift gears, the RPM's drop extremely fast, and if I don't shift fast enough the car will stall within a second. My idle right now is roughly 450-500, and it dips every couple seconds, nearly stalls and then climbs back up. Spark plugs are brand new as of about a week ago, and there are no vacuum leaks. Vacuum is a good -25hg under decel and -24hg at idle, which is what it has always been since I installed the gauge. Does anyone know what this idle problem could be? If I drive normally the car won't stall, so it only seems to happen when the clutch goes in after hard acceleration.

 

[Subsparx]

It's also worth noting that the EGR was cleaned 1 month ago, and the car was also seafoamed at that time.

EDIT: This problem could have been around for a while. I have a habit of double clutching and rev matching due to my RX-7 not having syncro's (updating as questions are asked on other forums.: I'm running both a BPV and BOV. The BOV is an HKS SSQV and has never given me problems in the past. All vacuum items (aside from the MBC) are supplied with vacuum via a vacuum block installed on the brake booster just like Swirl's. The car also has no issues with idling or stalling when the boost controller is installed in reverse (however I get -30hg's of vacuum under decell). This problem also occurs when the MBC is not installed.

 

[ucMP3]

Sounds vaccuum related to me... I'm not very well educated on F/I systems tho so I'm not sure where I would start looking.

 

[Subsparx]

That's what I thought too, but the puzzling thing is that the issue happens with a known good vacuum line being run directly to the wastegate with no mbc in between. The problem only seems to be fixed with the MBC is installed in reverse and the wastegate is effectively cut off. I'm also throwing a too lean code at idle.

 

[ucMP3]

I'm also throwing a too lean code at idle.

Then I would guess that you should look at your fuel system then. Or maybe a solenoid or sensor is malfunctioning and it can't adjust the ratios properly when you are driving hard @ WOT. If you're throwing a code, thats likely an issue. If not the only issue, it may still be playing a role in the problem.