Quick question on retunes
Quick question on retunes Setup is an 04 GTO LS1, H/C, running MAF, NGK AFX (recently calibrated) tuned on EFILive by RPMSpeed.
I'm mostly curious as to what environmental factors would cause AFRs to skew a bit. The elevation difference is only ~400 feet from where the car was tuned and where it is now, and my understanding is that the MAF should be able to adjust for this anyway.
The car runs good, pulls hard, but idle/light cruising AFR ranges 14.0-14.6, and I've seen WOT hit 13.64. I don't have logs of this, just visual observations at this point, but that's a little rich and a little lean for my liking.
I'm planning on picking up HPTuners to tweak this a bit, since it seems that there aren't many great LS tuners in the Pittsburgh area. I wouldn't think RPM would tune for these AFRs, although I can't view the tune just yet, but I was curious if something else may have skewed the numbers from then until now? What sort of conditions, aside from actual setup changes, are known to affect things?
I'm mostly curious as to what environmental factors would cause AFRs to skew a bit. The elevation difference is only ~400 feet from where the car was tuned and where it is now, and my understanding is that the MAF should be able to adjust for this anyway.
The car runs good, pulls hard, but idle/light cruising AFR ranges 14.0-14.6, and I've seen WOT hit 13.64. I don't have logs of this, just visual observations at this point, but that's a little rich and a little lean for my liking.
I'm planning on picking up HPTuners to tweak this a bit, since it seems that there aren't many great LS tuners in the Pittsburgh area. I wouldn't think RPM would tune for these AFRs, although I can't view the tune just yet, but I was curious if something else may have skewed the numbers from then until now? What sort of conditions, aside from actual setup changes, are known to affect things?
Just wondering if they tuned the car with the same wideband you are getting your readings from, or did they use their dyno's wideband screwed into your bung? Tail pipe sniffer?
Have you verified the fuel pressure is the same as it was? Fuel pump on its way out?
Did you do the "free air calibration" that NGK AFX requires?
Have you verified the fuel pressure is the same as it was? Fuel pump on its way out?
Did you do the "free air calibration" that NGK AFX requires?
Yep, free air calibration, sensor in the air for 5 minutes, per NGK's instructions.
Fuel pressure looks fine (there's a gauge on the rail,) and it's a Corvette regulator so no pressure adjustments there.
That's a good question on the wideband placement and stuff, but I'm not exactly sure.
Fuel pressure looks fine (there's a gauge on the rail,) and it's a Corvette regulator so no pressure adjustments there.
That's a good question on the wideband placement and stuff, but I'm not exactly sure.
At idle and cruise your ECM is in closed loop and will use fuel trims to target 14.7 AFR. Unless your fuel trims are maxed at -25% you should be hitting the 14.7 target. That makes me suspicious of your wideband calibration.
I'll calibrate it again tomorrow, leaving it out longer. NGK recommended 3-5 minutes for used sensors, and I believe 30ish for new, but really if I had to leave it sitting for a half hour it wouldn't be a big deal.
The wideband is after the y-pipe, basically where a rear O2 sensor would normally sit.
The wideband is after the y-pipe, basically where a rear O2 sensor would normally sit.
I'll calibrate it again tomorrow, leaving it out longer. NGK recommended 3-5 minutes for used sensors, and I believe 30ish for new, but really if I had to leave it sitting for a half hour it wouldn't be a big deal.
The wideband is after the y-pipe, basically where a rear O2 sensor would normally sit.
The wideband is after the y-pipe, basically where a rear O2 sensor would normally sit.
http://www.bmotorsports.com/download...ual_REV_06.pdf
So, did they tune it with their wideband, or yours? and where was the wideband bung placement when they tuned?
As an update, I calibrated the sensor again. After a minute or two, the gauge read CAL - and stayed there for the next 45 minutes without me adjusting it.
I noticed that when I started the car, fuel pressure was 58/59PSI. I drove around for a bit, and had AFRs at cruise/idle in the 14.0-14.5 range, and WOT in the mid 13s. When I got home, I noticed fuel pressure was down to ~55PSI. This is with a rewired Supra TT fuel pump and a C5 regulator/filter. This seems suspect, but I didn't have time to measure voltage at the pump.
The wideband is ~58" from the tailpipe, and ~47" from the longtube collector. I didn't measure the primaries, but obviously it's a little further back than NGK recommends. I'm not sure that this would be the cause of the numbers I'm seeing, though, based on some other posts where people didn't see this big of differences between their personal sensor in the system and a shop-mounted tailpipe wideband.
I'm not sure who's wideband it was tuned on, or where the placement was. I ordered HPTuners, but the drop in fuel pressure seems like a potential problem area anyway.
I noticed that when I started the car, fuel pressure was 58/59PSI. I drove around for a bit, and had AFRs at cruise/idle in the 14.0-14.5 range, and WOT in the mid 13s. When I got home, I noticed fuel pressure was down to ~55PSI. This is with a rewired Supra TT fuel pump and a C5 regulator/filter. This seems suspect, but I didn't have time to measure voltage at the pump.
The wideband is ~58" from the tailpipe, and ~47" from the longtube collector. I didn't measure the primaries, but obviously it's a little further back than NGK recommends. I'm not sure that this would be the cause of the numbers I'm seeing, though, based on some other posts where people didn't see this big of differences between their personal sensor in the system and a shop-mounted tailpipe wideband.
I'm not sure who's wideband it was tuned on, or where the placement was. I ordered HPTuners, but the drop in fuel pressure seems like a potential problem area anyway.
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Sounds like a poor tune and/or not 100% accurate measure of fueling.
I would put the wideband in the collector of the header, before any cats, and then check again. That far back and if you have cats will skew the readings.
I would put the wideband in the collector of the header, before any cats, and then check again. That far back and if you have cats will skew the readings.
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Verdad Gallardo I could've sworn I put this, but I looked and I didn't. No cats in the system.
I'm going to check a few other things and report back, but have others experienced a drop in fuel pressure by a few psi after running the car for a while?
I'm going to check a few other things and report back, but have others experienced a drop in fuel pressure by a few psi after running the car for a while?