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Turbolarry - more S-AFC questions w/mods
Ok, turbolarry, just when I thought I had this stuff mastered, I've gone and hit a snag. Back when I had JUST the S-AFC, I was able to tune my car to .91-.93v 02s with a beautiful timing curve that went up to 20-22 by 7500rpm. At the low end, my timing was dipping like it's supposed to at the point of peak torque (~3500-3600), then it would bottom out around 2-3, and finally it would immediately start climbing back up quickly en route to a final of 20-22 like I said before.
But now, I have a 3" cat-back, MBC@21psi, and MR BOV, and I can't seem to get it all right anymore. I also am dealing with quite a significant shift in temp/humidity, so that's another variable that I'm not sure about...I believe it is affecting things, of course, but I don't know which direction it sends my readings.
Anyway, since my logger is in the car, I'll have to give a rough estimate, but it should illustrate the problem:
RPM O2 Tim
2500 .83 16
3000 .89 7
3500 .93 -2 ??
4000 .91 -2 ??
4500 .91 0
5000 .91 4
5500 .91 8
6000 .91 11
6500 .91 14
7000 .91 17
7500 .93 17
As you can see, I have pretty smooth O2 and timing curves, but I have _NO_ idea why my timing is dropping into the negatives and then taking a good 1000rpm to start climbing again. I used to dip to only 2-3 timing, and then start to climb right away, which gave me time to reach 20 by ~7000rpm. Now, since I'm still at 0 near 4500rpm, my timing isn't able to advance far enough...plus, it's lower at each rpm than in the past, which means I'm probably making less power throughout. The problem is that I'm not rich OR lean from 3500-4500, so I don't know how to fix the timing. I could richen everything up to get it at 93, but if you notice 3500, it's already at 93, but still drops to -2 and stays there through 4000rpm.
Any ideas on how to improve this? I'm actually all the way to +3 at 4k and +2 at 4500 as far as the S-AFC goes. I don't start to go negative until 5k on the S-AFC, and then it gradually increases every 500 rpm.
Oh, the one good thing out of all this is that I hit a peak of 1870hz on the Karman readings, so either I'm getting faulty readings, or I'm making 300 or more whp.
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