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RB20 runs rich and sloppy then leans out under boost

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OK, So heres what im dealing with right now. My rb20 is having some weird issues running, Idle is good at a 14.7 AFR but under load/driving is where I get problems. Upon initial acceleration or low rpm`s the engine has little power and runs like its missing a cylinder or two with afr`s dipping into the 10`s then as boost comes on it runs normal for a bit like it should with afr`s towards 12-13`s and as the rpm`s raise and I hit full boost it will sputter and pop as it leans all the way out untill my wideband cant go any higher (18+ afr`s). So far I have checked everything manually and also through nistune and I still cant figure it out.


Here is my current setup:

Stock RB20DET and stock turbo


Nistune chipped ECU

RB26 444CC injectors (and resistor wired into the harness)

Walbro 255 fuel pump

Nismo FPR

AEM Wideband


I have checked the timing and its at 15 deg. Fuel pump has good power and ground. All injectors are opening/closing. All coilpacks work (I pulled them with the plugs and spun the CAS to double check). ECU dosent pull any codes. Fuel pressure isn`t dropping off. TPS voltage is good. Plugs look good and are gapped to the reccomended .8, The MAF readings look linear and accurate from what I can tell through nistune. If I go into nistune and bump up the fuel it just runs richer in the lower rpm`s and still leans out and pops. The only things left I can think of is a bad MAF, Low voltage to the pump under boost, A bad ignitor for the coilpacks, or possibly a bad CAS or something. Any help would be greatly appreciated because I dont know what else I should check at this point lol.

Edited by GabeDiaZ27
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