My buddy just completed a motor rebuild and he can't get his 1990 IROC to fire. He checked the module and it's fine. The coil checks out as well. The thing ran good before the motor swap and we must have something miswired or ? It's a speed density motor. Any suggestions would be greatly appreciated. He has had the top end off this motor previously with no problems but he feels like it's something simple he's overlooking.

 

hey i know this is like 2 years old but do you happen to remember what was wrong with your engine? im having the same problem now. and i can't figure it out

 

Well, first thing is to check the power supply (+12v) at the coil with the ignition on.
Next, try cranking without the EST connector disconnected.

Next...The ECM supplies the override pin (pin B on the module, look, it's labelled) with +5v when the engine is running. That is what tells the spark module to let the ECM control the timing. If that pin is getting +5v in crank, the car will not start correctly.