RB25det Misfire/Boost Cut

[bistratoaie]

Hey guys, its probably been discussed before but this is a new one for me ? 

I have a misfire/boost cut issue, not sure exactly what it is, list shows what's been replaced recently!

New Series 2 AFM

New BKR6E Spark Plugs (0.8MM)

New Series 2 Splitfire Coilpacks

New Coil Pack Harness Loom

New RB20 10psi Actuator

New Turbo Gasket Kit

New Exhaust Manifold Gasket Kit

New Intake Gasket Kit

New Exhaust Gaskets

New ARP Head Studs

New 1.3MM MLSR Cometic Head Gasket

New Gates Racing Timing Belt

New TruFlow Water Pump

OP6 Neo Turbo

Aswell as New Xtreme HD Clutch just freshly installed.

Seems to have developed a misfire think it was cylinder 6, taking it to a Skyline Specialist in a couple weeks, just seeing what else I could try on here first! ?

Stock ECU atm, got a fresh Platinum Pro waiting to go in.

Happy New Year ?

Edited December 28, 2018 by bistratoaie

[GTSBoy]

If it's a real misfire on #6, and you have all new ignition gear on it, then we will assume that it's not ignition.  But nevertheless, swapping coils &/or plugs around and seeing if the miss moves is a worthwhile diagnostic.  If it's not spark, could be a bung injector.  If it's not those things, then it may well be internal.  Have you done a comp check or leakdown?  Cometic gaskets have very particular surface finish requirements.  Was it put on properly?

If it's not an actual miss and it is instead a boost cut type issue.....OP6 turbo running at 10+ psi will possibly overrun the ECU's happy spot on the AFM signal and call a halt to the fun.

[bistratoaie]

1 minute ago, GTSBoy said:

If it's a real misfire on #6, and you have all new ignition gear on it, then we will assume that it's not ignition.  But nevertheless, swapping coils &/or plugs around and seeing if the miss moves is a worthwhile diagnostic.  If it's not spark, could be a bung injector.  If it's not those things, then it may well be internal.  Have you done a comp check or leakdown?  Cometic gaskets have very particular surface finish requirements.  Was it put on properly?

If it's not an actual miss and it is instead a boost cut type issue.....OP6 turbo running at 10+ psi will possibly overrun the ECU's happy spot on the AFM signal and call a halt to the fun.

Pretty sure it stays in #6. Injectors were cleaned and flow tested when head was removed, haven't done a comp test yet or leakdown, definitely need to do those! I'm 99% sure head gasket was put on correctly.

Yeah I had that boost cut when I first put the actuator on, replaced spark plugs with 0.8mm instead of 1.1mm and coilpacks with 2nd hand splitfires, and had no boost cut issues after.

[GTSBoy]

2 minutes ago, bistratoaie said:

Yeah I had that boost cut when I first put the actuator on, replaced spark plugs with 0.8mm instead of 1.1mm and coilpacks with 2nd hand splitfires, and had no boost cut issues after.

That doesn't make a lot of sense.  Boost cut is an ECU function, not an ignition system health issue.  Making it work better (more power) should make a boost cut worse.

It's not necessarily a boost cut anyway.

The other consideration is boost leaks, injector seal leaks, etc.

[bistratoaie]

Didn't make sense to me either but it worked? the actuator is 10psi.

I am thinking maybe a boost leak somewhere