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Old 08-21-2007, 08:30 PM   #1
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Default What does this scan data tell you?

At WOT
BLM 140 to 150
BLM CELL ~13
Integrator 128

It was quite lean, the the PCM has more or less figured it out?

There was no KR if I floored it and there was a good solid down shift. If I floored it at a point that it wouldn't down shift, there would be a few degrees. I saw up to 20 deg retard if I floored in second at RPMs just too high to down shift to first.

Keep in mind my setup:
Gen 3 M62 with TB and MAF, roller rockers, PEMs, AFPR set at 54 psi. NO AFC.
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Old 08-21-2007, 11:52 PM   #2
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No idea what a BLM or integrator is.....
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Old 08-22-2007, 12:14 AM   #3
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I think BLM is LT, Integrator it ST, and BLM cell is what it'* trying to do to keep the integrator at ST...?
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Old 08-22-2007, 02:59 AM   #4
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Here'* an explanation of BLM and Integrator (OBD I PCM speaks 8-bit ):
http://www.gnttype.org/techarea/faq/BLMINT.html
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Old 08-22-2007, 11:34 AM   #5
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You're running that at 3.7bar? That seems high, assuming you're on the 2.5 pulley. I run mine at 3.5bar when I have the 2.5 pulley on, and that'* with Gen3, Ported LIM, Ported heads, and 1.8 rockers.

I run 4bar (maxxed out) with a 2.3" pulley.

If you run it too high, you may have fueling problems at the lower RPM'* under load. I'd back it down some, however, your BLM is high. You'd like that to be about 128.

I'm surprised the PCM is trying to richen you with the AFPR set that rich. In the long run, you and I may both benefit from a rising rate regulator rather than an AFPR. It'* something I've looked into in the past, and will work VERY well with a stock PCM or mild tune. They're expensive though, and you have to really nail down the range you need, but with the AFPR and a wideband O2, it'* alot easier to figure out.

My BLM runs 128-135 under most conditions. It occasionally hits 140 under load, not quite WOT. This is why I'm going after bigger injectors, and I'm selecting them to target 3.5bar of fuel pressure, in case the AFPR ever fails, I can fall back on a stock S2 FPR at 3.5bar.

Keep in mind my wideband O2 looks VERY good, except I'm not running quite rich enough at the top end. I'm rich there, just not 'safe' rich. I run 12:1-12.5:1 at WOT, and ran at Woodburn that way. The overly-oxygenated race fuel I was running didn't help my problem any as you might imagine. My scans are really good too. SSEiMatt93 and Slayer636 went on a couple scan runs with me using 2 different pulleys during WCBF.

The injectors I've chosen are stock Grand National (Turbo V6) or Turbo Trans Am (GTA) injectors. I'm currently running my stock 29lb injectors at 4bar, which flows them at 33.5lbs. If I were to jump to the stock S2 injectors, I'd have to run the stock 94/95 L67 FPR which is 2.7bar, and that would net me 34lbs. With the 3bar regulator or the AFPR backed all the way out, they would be flowing at 36, which is too rich and will upset my BLM'* at the lower RPM'*.

But with the injectors I chose, I'll be running 34.5lbs at 3.5bar. As close to perfect as I could hit, and coincidental considering the stock application those injectors are for.

For those wondering about the flow differences between S1 and S2, the primary difference is simply the higher RPM'* the S2 operates at. John, you might want to try an old set of 36lb L67 injectors with a 2.7bar regulator and just see what the PCM tries to do. I wouldn't run that long-term, since you'd give up the advantages of a higher fuel pressure in consistency and better fuel atomization.

A word of caution:

There is no POWER in larger fuel injectors unless you're going static before WOT on your stockers. There are very few cars here that can outflow their stock injectors, and I see many people on automotive forums selecting larger injectors FAR too early. This actually hurts performance, and requires a custom tune to get them right. You can compensate by raising the fuel pressure, which I believe is always the FIRST step. Always tune mechanically as far as you can before resorting to PCM tuning.

I don't want to see a bunch of mildly-modded S1 L67'* running out and grabbing GN or TTA/GTA injectors. They'll wreak havoc on your fuel trims and hurt your performance.
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Old 08-22-2007, 11:53 AM   #6
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Since my LT is flirting with the max, if I back off the fuel pressure, won't I not be able to get enough fuel?
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Old 08-22-2007, 12:15 PM   #7
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Alot depends on how much you trust your O2 sensor.

This is where the value of a wideband really comes into play.
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Old 08-27-2007, 05:03 PM   #8
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Alright, after a few days with my spare MAF, the LT has slid a little in the right direction, but not much. I haven't sprayed anything to check yet, but I do hear hissing in the BCA/boost side vacuum tree area.
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Old 08-27-2007, 05:19 PM   #9
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Good. Sounds like we're homing in on it. I'd expect you to be about 3.5 bar on the regulator by the time you hit 128 for the BLM.
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Old 08-28-2007, 11:26 PM   #10
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Found my vacuum leak. My selfmade EGR tube gasket wasn't gasketing. When sprayed with TB cleaner, idle stumbled and it almost died a few times. I flipped the gasket around so the smaller hole was around the hole instead of the bolt. Sprayed again, and now idle raises just a bit. It'* not perfect yet, but I think it'* better. We'll see what the BLM does now.
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