I pulled Key On Engine Off codes and got:
31
22
53
54
35
67
51
Any ideas?
When I try an engine on test my car just sputters and almost floods out. I don't even have time to check the reader. My setup is a 92 computer and harness on a 1988 gt.
31 = EGR valve position sensor voltage is too low, circuit problems
22 = MAP or Barometric pressure sensor is out of range--check the MAP and BP harnesses
53 = TPS voltage is too high (indicates a WOT condition) check for shorted TPS/harness
54 = ACT/IAT sensor voltage is too high--check for shorted sensor or harness
35 = EVP or PFE voltage above max limit during operation
67 = Car is in gear or A/C is on (make sure you take it out of gear and turn off the HVAC controls next time)
51 = ECT voltage is too high (reads coolant is cold, make sure you warm up the car before pulling codes)
First check your physical grounds. It sounds like you may have fried the signal return on pin #46 (it's a circuit ground, common to all the sensors you're getting codes for).. I went through the same thing. Check the resistance between the highlighted self-test port and battery negative, it should be grounded.
What method are you using the check the codes? If you use the check engine light, try running jumper wires from the highlighted port AND the self-test input connector to battery negative, then do a KOEO test. If the codes go away, that will confirm your problem is with pin #46.
If that works for you, you can just crack open the computer, locate the point on the circuit where the burn is, and solder a short length of wire to bypass it. I've done this on several computers successfully, and it's the most common fix found on a refurbished eec-iv.