Miss at 4k RPMs and up!!!

[foulplay]

INFO: Alright, how u guys doin? As you may know, I have a RB20 in my S13, with FMIC, 3" exhaust, Walbro fuel pump and NISMO AFPR. I have the fuel pressure set at 35psi with the vacuum attached, replaced ECT sensor and O2 sensor.

PROBLEM: Now my problem is when I stomp on the gas everything is all good until 4k RPM and above, then its starts missing and popping like a biatch.

The weird thing is, I can gradually give it gas and it will not miss and pop at 4k RPM and beyond.

So can anyone please give me some input on how to resolve my problem, b/c my Dad and I have been trying to fix this problem for the past 3 weeks and about to pull our hair out.

ThanksDanny

[matafied]

sounds like you have some arching going on or your spark is breaking up! out of the 3 rb powered cars i have, and the local skyline it has happend to us all lol you can start by gapping your plugs to .8mm and if that dont fix it you can try rapping the bottom of the coils in electric tape to prevent them from arching to the coil bracket. i did this for a couple mounths till i was able to convert my coils

zerothread?id=219934

[firstwizardshawn]

just me but it could also be the maf sensor! i know they are totaly different vehicles but on my blazer it done the exact same thing. changed maf and runs like a beast. check your ecu for some codes maybe there might be an answer in there! but if you have an extra lying around try it!

[foulplay]

I got lucky, stretched the springsin the coil packs a tad and miss is gone. My 240 now runs like a scared rabbit.

[Spazz]

what matafield said is true, electrical tape the bottom of your coilpacks.i had the exact same problem you had... damn coilpacks

[ST240]

sounds like you have some arching going on or your spark is breaking up! out of the 3 rb powered cars i have, and the local skyline it has happend to us all lol you can start by gapping your plugs to .8mm and if that dont fix it you can try rapping the bottom of the coils in electric tape to prevent them from arching to the coil bracket. i did this for a couple mounths till i was able to convert my coils

zerothread?id=219934

I'm bumping this thread just because of how valuable this info is. It seemed like i had fuel cut or some sort of afterfiring (but quieter) at WOT above 5-6k rpms or so. I pissed around with fuel pressure and tried to find a boost leak, but no luck. I read this, tried it out and it GREATLY improved the problem; it only sputters slightly now, barely affecting performance.

That coating thats on there heats up and flakes off, then you get arcing, which makes sense. But you can do a better job than using E tape. I'm going to the hardware store tomorrow to get some kind of coating and be done with it.

Thanks man!