Originally Posted by
LeMarky Dissod
Even if a '79 Malibu wagon weighs a bit less than an F-car, I would not change the max line pressure constant (in part because it's not what you think!), or lower the main line pressure tables. They were already mild to begin with. OE line pressure constants & tables aimed for unrealistic MpGs, at the cost of the 4L60E's longevity.
I adjusted the speedo scalars for 26" tires & 3.73 (more precise tire measurements - between 25.5?" & 26.5?" - would help, or err a wee lil bit on the tall side), and the upper limit speeds in the 'Normal', 'Performance', 'Manual', 'Cruise', & 'KickDown' tables, as well as the 1st gear limit constants. You can do much more to improve the rest of the shift table speeds, of course - GM has always been beholden to CAFE MpG test results. Even GM's Performance Mode table is pretty lame.
At sufficiently high throttle angles, setting the KickDown constants so that shifts reference RpM instead of MpH is safer for the engine.
At lower throttle angles, MpH shift points are fine if the speedo constants are accurate enough.
Raise the max line pressure constant & main line pressure tables back to OE F-car specs, at a minimum.
If your wagon weighs enough, consider using the B-car 9C1 and/or the D-car V4P main line pressure tables; the lesser B- & D-cars also traded 4L60E longevity for MpGs only hypermilers would easily achieve.
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