870 Spark Control

[Matt Sandine]

The way I see it, the ESC, EST and ECM are the only 3 things in this setup that can control advance/retard in this computer. When I go through the normal routine of setting my timing at 6deg BTDC with timing connector disconnected, that works out fine. Then, when I plug the bypass back in, the timing RETARDS a good 24 degrees. I just replaced the ESC module because I thought if it was bad, it could cause full retard but it wasn't the case. I took all spark retard out of the chip and it still did the same problem. Unplugged knock sensor-samne thing. Swapped ECM's and it still happened. TDC has been verified many times with a piston stop. What electronically could be causing the massive timing retard? The EST has also been replaced and verified with a spare one. All wires have been rung. Oh, boy. Thanks in advance, -Matt-
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