I could use some help from this community on a tuning issue. I'll put some specifics and a log file lower down. In short, my AFR gets close to target (11.6) under WOT, but then leans out (13.5). This causes expected Knock Retard. I put a video camera on my fuel pressure gauge and then transcribed the date (blue line below). The graph shows a WOT run, 2nd and 3rd gear. The fuel pressure regulator is boost referenced so fuel pressure jumps up with the MAP. But, the fuel pressure falls off too early. Do I just need a better fuel pump? Are there other things I should look at first?
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I haven't messed with the fuel adder tables. Since my commanded AFR values look correct, I assume these adder tables aren't the culprit. My injector flow rate table is essentially flat, which some research shows is appropriate for a boost-referenced FPR. I haven't changed anything major on this tune, aside from MAF adjustments to get the idle and cruising LTFTs close to zero. I suspect this leaning AFR issue has been happening for a long time. I only recently got HP Tuners.
Specifics: Pontiac Fiero with an engine from a Grand Prix GTP. 1998 3800 SC (L67) with a Gen 5 blower, Northstar throttle body, and headers. Intense Stage 1X Blower camshaft with 105# valve springs. Light DIY port on the heads. 42 lb Lucas injectors. 3.4 pulley and attempting to tune for 91 octane. The fuel pump is stock for the GTP. Here?s the log file.
Thank you!