870 Spark Control

[Programmer]

Matt,

If this thing was going into 24 degrees retard from 6 BTDC, it'd stall. Are you 100% sure it's going 24 ATDC ?

Lyndon.
  ----- Original Message ----- 
  From: Matt Sandine 
  To: gmecm at diy-efi.org 
  Sent: Friday, May 11, 2001 11:37 AM
  Subject: 870 Spark Control


  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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