RB20DE+T 14psi miss firing on boost

[Elliot]

Hi everyone,

I have had my car tuned a few times now. My setup is the following:
RB20DE+T
Standard turbo exhaust manifold
RB25DET R34 NEO turbo 45v4/OP6 housings
Front mount intercooler
Custom front facing intake manifold (similar to RIPS or Sinco)
Scarles ignition coils
Z32 airflow meter
390cc Mitsubishi GSR injectors
Tomei fuel regulator
HKS EVC-S
Nistune ECU
Also was setup for external wastegate at the of tune but currently running internal wastegate

I had it road tuned back in October. We started the tune around 9pm so it was dark and relatively cool. Probably around 17-18 degrees. No wind. We got it all tuned started tuning from around 9psi and by the end we had it up around 14.5psi. Which is a lot for that turbo. Because of the front facing plenum it doesn't have much low down torque but it loves to scream all the way to 8500rpm. On the night of the tune it pulled cleanly with no issues what so ever to 8000rpm which is were we set the limiter. This was on a Saturday night. Sunday it ran good too however still had a missfire when coming onto boost when warming up, understandable though as it's running in enrichment tables and what not. Once warmed up it ran like a dream.
On full boost the afrs are 11.2-11.5:1. The ignition timing is a measley 7-8 degrees on full boost between 3200-8000.
When we were tuning it we were measuring both afrs and had knock headphones.

Since the tuner flew back home it's started to missfire on boost or completely drop all timing and run probably below 0 degrees. When it pulls all the timing it does it as soon as I roll onto boost anything above 3-4psi @ 3000 rpm. This was on the external wastegate also I have since changed to the internal wastegate and dropped the boost down to 10psi. This didn't improve anything. Thinking it might be faulty knock sensors giving a false reading I unplugged the loom and tricked the ECU with 470k resistors. Doing this didn't pull any fault codes however occasionally now when doing a pull it would go but it would missfire and stutter. And on the odd occasion it would fully pull the timing. I haven't checked the fault codes since as I'm pretty sick of it now.
At the time of putting the resistors in place of the knock sensors I also put a brand new set of bcpr6es spark plugs gapped to 0.8mm. I have tried 0.6mm gap in the past but didn't resolve the issue.

The only issue I had when tuning is we couldn't get the idle mixtures around 13.5 because there is a vaccum leak around a couple of the injector seals. However this shouldn't cause a huge problem on boost should it?
I've done a few logs and it doesn't do anything odd like not moving through the map etc. I'm at a lost end and any suggestions are appreciated!

[bachig24u]

Fix the vacuum leak as it would turn in to a boost leak spraying fuel mix in the engine bay.

post some close up pictures of the spark plug electrodes.
ensure to number them so I can see which cylinder they came from.

[Elliot]

I'm currently on holiday with the car around 170km away from home so when I get back home on the 5th January I'll take the plugs out and put up some photos. The plugs at the time of pictures will have done around 400km. The last set that I took out were perfect in colour but were only in for around 200km.

I'll order some new seals too when I'm back. It is the seals around the pintle cap and plenum.

[SeriouR]

Scarles ignition coils are cheap and nasty, that's where i would look first.