EPC Light at high RPM, EQT tune second revision *Update: Car is now a hot mess


Autocross Champion
In the second revision of my Vortex standard tune on 93. Car logs looks great so far:

Datazap link

With the exception that under high load and RPM I seem to consistently get an EPC light and the engine goes into limp mode of sorts with no engine light. Cycle the key and all is normal. So long as I stay under 6k or so car runs strong! The base tune which pushed 25psi never gave me an EPC light. In this revision I am pushing 30-31 PSI, so quite a bit of difference in boost. Log from EQT base tune.

At first I suspected a fall in fuel rail pressure, EQT informed me that fuel rail pressure looks good. Only code is some unknown code, note the value above static where the code should be is blank:
2022-03-25 16.02.17.jpeg

I may try and pop the EPC light while logging misfires in OBDEleven. Running ruth plugs with only 6k miles on them, they looked great the other day when I pulled them for an intake valve cleaning so I doubt those are the issue. It could be that one of the coils isn't up for the job under the higher cylinder pressures. Thankfully this would be easy to diagnose. I remember reading the stock coils may need replacing at 80k miles...mine have 75k miles on them and I am throwing all this boost at them.

Anyone have anything to add? Oh, I do have an EQT LPFP on the way which will go in when it arrives.

Edit: Log after LPFP
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Autocross Champion
Out of fuel.
Can you elaborate? This is what EQT said:

The LPFP is maxed out though, which is why I initially suspected a fueling bottleneck.

Could this be on of those situations where pressure looks good but fuel flow ain't there?


Autocross Champion
afr not hitting target
HPFP is maxed
inj pw is rising
stft rising

It's running out of fuel.
Thanks Diggs!

I did notice the AFRs creep up a bit over 6500, but I didn't look at the stft % until you mentioned it. They both seem to coincide for sure with stft peaking at 8%:

Screenshot 2022-03-29 091701.png