[Supras] Lexus AFM + 550cc injector head scratcher

[berniek at technicaldevelop.com]

Hi list.

    The original Reg information about the AFM-injector modification painted a pretty simple picture.  Some list members I've exchanged information with have done the mod without additional electronics by setting the AFM bypass screw and pressure of a replacement FPR.

    However, in reading some old tech postings, the point was made that the ECU calculates spark retard values under boost by reading the Karman vortex frequency.  Since it will be about 20% less for a given air flow with the Lex-550cc modification, the ECU will not retard the spark as much as with the standard setup.

    Of course, the knock sensors will cause the spark to retard, but should not be relied upon in the normal course of operation.  I'm curious if anyone has considered this point or has had any problems in running the Lex mod without electronic add-ons.

    Thanks.

        BernieK