[Supras] FW: LEX-stock AFM comparison

[Glen K]

You are giving the stock ECU too much credit, the stock AFM and injectors run very rich under boost. As far as fuel mixture is concerned the lex AFM and 550's offset eachother bringing you right back where you started (ignition timing is a separate issue) This is why some people run the lex AFM with stock injectors. You are correct about the ECU learning in closed loop and using that information under open loop conditions, but all that does is assure that it stays as rich under boost as Toyota wanted it to be which is much richer than you would like it to be. Glen>     I've read about the Lexus AFM-550cc injector upgrade, which I intend to do.  But there is one perplexing question:  Since the Karman Vortex effect is linear with respect to volume air flow, why does the Lex-550 combination run too rich under boost?  The stock ECU appears to extrapolate from stoichiometric under normal conditions when you put your foot to the floor.  So the percentage increase in fuel should be the same, once the ECU "learns" the fuel trim from the O2 sensor, from either the stock setup or the Lex-550 combination.> >     What am I missing here?> >     Thanks.> >         BernieK

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