Quote:
Originally Posted by dannichols1474
No, I am running the CIS Fuel Accumulator between the fuel pump and the FPR, then the fuel supply deadheads to the fuel rails.
Regarding your long term fuel trim screenshot, do those dips move around from one run to another (that is moving to different rpm / TPS conditions)?
My experience with OEM emissions systems is that long term trim changes more slowly. If the LTFT dip persists, then it would indicate the base fuel trim map is too rich in those areas - 1500 to 2500 rpm at low TPS is like pulling away from a stop with light throttle then cruising around the neighborhood?
Anyway, back to my fuel set up and observed fuel pressure changes. While Gary Bains was running the car on the dyno, I stood at the back of the car and watched the fuel pressure readings (my MegaSquirt 2 doesn't have an input for fuel pressure).
When Gary floored the gas (WOT) at 2000 rpm, the fuel pressure would drop from 50 to 48 psi then recover to 50 psi after 1 second or so and then stay steady at 50 psi through the rest of the WOT ramp run until after 7000 rpm and the fuel pressure would start to drop slightly (not sure of the amount, only that I started to see the gauge slowly moving lower), but then at 7300 rpm Gary ended the ramp run and the fuel pressure went back to 50 psi. That indicates to me that my fuel pump may be getting flow limited above 7000 rpm. If I was a racer, I would be thinking about a higher flow rate fuel pump, but for canyon carving and cars & coffee duty I am okay with what I have.
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The graph represents the long term trim after running the car quite a bit and applying those long term corrections to the base map. At this point, I shouldn't be seeing dips like that. You can see that the adjustments around the big dip area are modest. More to play with but I'm enjoying the process.
BTW, I finally drove the car, about 100 miles, on Monday without logging data. The laptop was with me just in case but it wasn't needed.