Hi everyone,I have a 1.8T BEX 20V engine and recently upgraded the turbo to a hybrid with a larger forged compressor wheel. The rest of the setup is completely stock, except for a high-flow exhaust manifold. The engine has just been refreshed (rebuilt cylinder head, honed block, new piston rings, rod bearings, new oil pump), and the intake system is 100% boost-leak tested and tight.Currently, the car is running on a completely stock map, and I am experiencing severe timing pull (ignition retardation) up to -10 degrees KW. This timing pull happens under both heavy and light loads.I am running the car strictly on 98 octane fuel (RON 98). However, during steady cruising, the timing correction stays at 0 KW.I checked the fueling, and the lambda is holding steady at 0.80 (requested vs actual matches), so the car is not running lean, but it keeps pulling timing aggressively anyway.My question is: Do I absolutely need a proper remap (recalibrating N75, ignition tables, filling tables, etc.) just because of the hybrid compressor wheel?Could the larger wheel be altering the airflow/mass and load calculation enough to trigger this heavy timing pull, or should I suspect mechanical "phantom knock" from the freshly rebuilt engine triggering the knock sensors?Thanks for your help!
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