fuel cut VS ign cut VS boost leak ?

[Silverbullet]

ok, i have a little situation. My car ran perfectly fine before. Just a few days ago, im expiriencing some type of cut. I figure it is a fuel cut, but im running stock everything so it dosnt make any sense. I'm only runing 7psi with Walbro 255 pump, and Z32 filter. I did some more runs on the highway just now and i've observed this only happens in high RPMs and full boost. It happens anywhere from 4000RPM to redline on full boost so it makes sense to me that its some type of fuel cut. Whats wierd is there is no other symptoms. I dont have idling problems, i dont have stalling out problems, i dont have any hesitation, spuddering, or studdering. Anyone have any ideas? i am stumped. Oh yea, it might possibly be a boost leak or an ign cut, but im leaning more towards this being a fuel cut problem because i dont notice any extra backfire or huge fireballs after my loss of power. I did some searching and most ppl who have identical problem with me ususally have their cars spudder or have crazy idle or something. Mine dosn't seem to do anything else at all.

[HaLo]

I had a similar problem one year ago and it was a faulty coilpack.
Might want to check that too...

[speeddreamz]

I doubt its a fuel, or ign cut. If you have a 300zx filter, it shouldn't change too much, but if you have a 300zx maf, you should check out the settings on your safc/emanage/ etc that you're using for tuning. Typically if you have the in and out settings for the maf sensor right, the correct amount a fuel / air adjusted is not always right.

Another thing could be under high boost/load the spark plugs? when did you last change them?

[Silverbullet]

the plugs are relatively new... half a year maybe? the NGK ones from Heavy Throttle. gapped to .28. I kno if the gap is too big, it'll break up under boost, but what will happen if gap is too small?

[g2ic02]

i would say that it is more than likely a boost leak....if you take a pull then it does the "cut" does it run good right after or do you have to let it idle a bit before it will come back to life??

[Silverbullet]

well heres what happens, i acutally turned the boost up and have observed that it is not a boost leak. The reason i say this is because i can easily hit 13 or so psi in the mid range RPM but it'll get the problem in the high range. It feels like i literally blew my motor or something. It will just stop accelerating and start to deaccel. I have to let off the gas for a few seconds before i can accel again. If its an ign problem, should be backfiring and what not however i am not getting that much backfire at all. Not more than normal. Any help?

[Silverbullet]

oh, i also swapped in a different ECU. Same deal.