93 Ranger project ignition timing issue?

[grantc1958]

1993 Ranger 2.3 5spd, 145k mi. Truck will start but not Rev above 1500 rpm. Have checked and ruled out TPS, MAF sensor, fuel pressure and flow, cam timing and vacuum leaks. When truck starts, ignition timing is 20 deg BTDC, when opening throttle timing retards to roughly TDC. ICM has already been replaced by prev owner. What the heck is going on?

 

[tomw]

Mebbe previous owner got the ICM module from his shelf, and popped it in ... and it is the wrong one. Check the part number for application as it could be incorrect.
To my knowledge, the timing should not be dropping back to TDC. Even 'static', open loop timing is set a a baseline of 10BTDC, at least on the ones I am familiar with.
As is noted here and there: "That's not right."
tom