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Originally Posted by Maxlean
Do you have any speculation as to why these particular calibrations are like this? I'm sure GM had a reason for this mode of opperation. And am I to assume that you run an open loop tune normally?
Scott
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Scott,
it makes good sense, actually. The fuel tables are different for PT open v. PT closed, so therefore it is logical that you would want the ability to apply a different long-term correction value to each case. One might say that would not be needed, since you'd likely be in Power enrichment under PT open conditions anyway. Not necessarily. Imagine the situation where you make a quick passing maneuver on the freeway, then quickly back off but not less than 4.7% TPS. The PTs would remain open until the TPS lower threshold is met, yet you'd easily be out of Power enrichment.
What I just can't grasp is why the seemingly random application of this enhanced BLM code. Why is it not, for example, in BFXB (one of the last service calibrations released)? For the most part, the later released cals are very similar in all other regards.
For me, I generally ran my 91 350/500hp in Open Loop. As long as you get the fuel tables very close to ideal, and run with consistent gas and ambient conditions, its not a problem. Its all a matter of preference, really. However, I did have it going on full-time closed loop dual Wideband O2 control for awhile, just to see if I could do it.
Todd