Hello, I replaced the engine in my 06 Outback with a new short block, rebuilt heads, turbo etc. As it sits at the moment, there is no aftermarket add ons only a stock configuration. While driving at partial throttle, it has a surge at 3000rpms more like a gentle surge as though someone is on and off the throttle very quickly. Looking at the data on the scan tool, short term fuel trim is up to 22% and long term is at 14% and has triggered a P0171 Fuel system trim too lean Bank 1.
It has a rough idle, I don't feel as though it's a misfire though.
Checked fuel pressure
@idle 33-35psi
@3000rpms fuel pressure goes from 40-55psi.
@WOT fuel pressure stays steady 40psi.
Going with the code P0171 Fuel system trim too lean, it appears the engine is trying to compensate for the lean condition up to 21% Whichever threshold it has until it decides to trigger the light.
Any thoughts guys? It's an all stock EJ255, automatic.
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