Bit'o help with my Ranger's eec IV gremlins please?

[chicoranger]

My '85 Ranger with the 2.8L V6 and feedback carb has issues. I was given the truck. I have dealt with getting the basics covered: charging system new, valves adjusted, compression checked and solid, new o2 sensor (Bosch), secondary ignition system replaced (rotor, cap, wires & plugs), fuel, air & breather filters new, new PCV valve, float level checked, EGR & brake booster & tranny vac modulator checked for vac leaks, all vac lines replaced as well as the usual propane checks for vac leaks.

It runs really well but will not go into fuel control because of the issues surrounding the following codes:

31 KOEO EGR valve control sensor fault. I swapped a known good EVP (EGR position) sensor off my '86 Bronco w/the 302 EFI motor and no change (checked & interchanged part numbers as good). My chart also shows EVAP control system below minimum voltage as a possibility for this code as well.

18 CM My chart says loss of tach input/IDM circuit failure/SPOUT circuit grounded. Since I have flakey insulation on the harness side of the spout connector I strongly suspect a SPOUT to gnd. issue. If I need to replace the spout to PCM connector wire do I need to use a shielded wire? Regular coaxial cable?

54 CM IAT sensor circuit open. I swapped another sensor of unknown status in for a quick check, no change.

With all the wires running underneath the hood on this sucker I guess that I'm lucky to only have three codes.

Any input much valued!

Happy Halloween!

chicoranger

 

[MrShorty]

I know very little (if anything) about the 2.8 and its feedback carb, so my comments will be very general.

Standard procedure is to resolve KOEO codes first. KOEO codes, because they are set when the engine isn't running, almost have to be electrical in nature. Have you checked the wires between the sensor and the computer? If your chart indicates a possible connection between EVP and EVAP, does it indicate how to test that connection?

After resolving the KOEO code, then run the KOER test and see what you get.

Before spending much time on CM codes, I would clear CM and test drive to see if the codes come back. Of course, this should also wait until KOEO and KEOR codes are resolved.

I was always of the impression that the SPOUT wire was a simple single conductor wire.