Though mine's an '87, I have used the '88 bin as my starting point for my tuning. This is because my cam's similar to the '88 cam and Grumpy says, "newer is better". Currently, I'm making runs, noting where knock is detected, and trimming the timing in that area. I have burned about a half dozen chips, each with the timing progressively cut in "critical" areas. I haven't gotten rid of it, yet and the curve has changed quite a bit from stock.

One thing about the stock '88 curve that puzzles me, though. The values at the 32 g/sec (the lowest load) level are way lower than those in the '87 bin. In the '87 bin, the spark values are essentially the same for 32, 48, and 60 g/sec. This difference essentially cuts the spark timing while cruising, and that doesn't make sense.

Can anyone explain why "they" might have done this? Also, does anyone know how values are determined for "loads" and engine speeds outside the table? Are the "last" table values used, or is some kind of extrapolation used?

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'87 IROC 5.7l TPI - original owner!

 

PJ, I can't really answer your questions, but I am glad that you are working on programming with a MAF car. I noticed the 88 spark table is the least aggressive, then the 87 350 tpi, and then the '89 ARAP bin has the most agressive spark timing. I switched to the '89 ARAP bin with the $6E TDF cal. I basically used all the numbers from my 88 bin that I could. So far, everything works fine, but the primary fan won't shut off. I think the fan pressure logic is reversed. I am waiting to hear from TC, to see if they can add this switch to their def file.

My plan is to back the intital timing back down to the stock 6deg, (from 10 now) and try the spark table from the '87bin. I don't want to go too aggressive, but I could burn as many chips as possible to make my motor happy. I am amazed at how much they are different from 87-88-89.

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Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!