My engine can't breathe..!

[Blues13]

I have a 90 S13 SR blacktop running @ 10psi.. it's been running great for a while. All of a sudden it's developed this problem.. under WOT the engine would boost to 10psi as normal but then as soon as it hits 10psi, the engine would kind of cut out.. it's what seems to be similar to what would happen if you redlined, as if the fuel was cut.. Although it's not getting enough air and would backfire a little.. Yes, I've searched the forums and this is what I've tried so far:

First, since I'm running the SMIC with a blitz bov, I thought one of the caps had come loose.. so I check all three caps and re-adjusted them so they were sealed completely.. problem is still there.

Okay, so I thought it was the BOV leaking under full boost. I have a Blitz SS and yes.. i know, they suck.. so I tried tightening the spring ALL the way down so that under WOT it would stay closed.. but problem is still there with added horse noise. I loosened it back to normal.

I rechecked all the intercooler piping, but they all seemed to be tight and normal..

So, what's strange is the car drives fine and normal until you hit max boost.. this would seem that there is a leak somewhere.. does this seem right? Do you guys have any other ideas what it could be?

There's been no smoke, no stalling, idles great, and up until 75%-100% throttle everything's been normal.. after that the engine starts to stutter. Boost seems to spool up like normal and there doesn't seem to be any noticeable increase in turbo lag.

I did find a little oil by the BOV which is making think there might be something wrong with the turbo.. but there's been no smoke under boost and feels strong up until 10psi.

Let me know what you guys think it could be... thanks.

[RedSuns]

10psi isn't much but when i would run 15+ on my s14 SR mine would do the saem thing. Is the cut-out of power kinda voilent. If is it violent like you explained it you coiuld be maxing out the MAF sensor.

[Blues13]

Yeah, it's a bit violent.. I've been running on 10psi for awhile with no problems. I'll try cleaning out the MAF sensor tommorow though.. thanks for the advice.

[jtt220]

cleaning it wont help if you have overstreched it's useful metering range. The sr's stock MAF can only meter so much air. Try upgrading to a larger maf like the z32 unit.

[Blues13]

Hmm,.. well, 10 psi has been working fine for almost a year and I think the stock MAF should be able to hold that... but maybe it's another problem.. anyone have other solutions or what it could be?

[Nostradamus]

I have the same problem with my RB25DET, it will cut out at around 12psi. My brother ran his SR20DET up to 12psi with no problems so I don't think it's the MAF. What I think it is... is the spark plug gap is too large. I do not know the SR20DET gap numbers off hand but they're way smaller than the RB25DET.

[Blues13]

This problem has just popped up when it was running fine before.. so I'm not sure its the plugs.. can the gap widen over time? but I will check them. Maybe they're fouled... will that cause it to do the same symptoms? Fouled plugs would cause a rough idle, no? It's idling pretty steady at 800 rpm.