2ZR Turbo Yaris

[06YarisRS]

Thanks Trevor. I blocked off the valve cover breather hose with my thumb while monitoring FTs. The suction on my thumb got stronger and stronger. In this situation the STFT actually started to climb and the engine rpm started to drop as though it was starting to struggle. At that point I removed my thumb and the idle went back to normal.

With the breather line open and around 3000 rpm, the STFT drops to about +6 to +7, down from +18 - +19, but LTFT remains at around +29. I'm leaning toward the different plumbing - airflow pattern/volume etc - throwing the MAF off and as a result the FTs and I hope that the MAF clamping via the F/IC should solve, or at least improve the situation. A lean code P0171 was finally set although AFR's always remain around stoich (14.6 - 14.8, so it seems the ECU still had control of fueling) and never deviated from that, except when the throttle was let off and it dropped to 18:1, but that's normal fueling strategy - my 1nz does that too as did the 2ZR pre-turbo.