CEL light on and Can't pull KOER codes.

1991 Fox LX with 347 5 spd. Trick Flow intake, heads, I think 303 cam. Aftermarket Throttle body and SCT Chip plugged into A9L. Car was running fine in cruise and then felt it bump and CEL come on won't go reset. Idle RPM is surging. Did find bad IAC it helped surging idle but still constant CEL and not able to pull KOER codes.

KOEO codes are 15 & 85.
I can't seem to pull KOER codes. Tried 3 different testers. Is this due to KOEO codes set (15, 85) ?
Charcoal Cannister inoperative/unplugged but parts on order for code 85.

Code 15 from what I have read is likely due to SCT chip?

How do I or can I pull KOER codes? Or can I with KOEO codes still on?

I tried Autoxray 6000 (says no communication with Engine running) and 2 different INNOVA EEC-IV (light & LED) code readers. LED version no codes with KOER. All three pull codes 15 & 85 KOEO. I do unplug negative cable when not driving everyday...But been doing that for years without issue due to not everyday driver.

Rather pull codes then fire off parts shotgun. O2's not been changed in a while and considering sending off ECU. Did change ECU 3 capacitors. Still had CEL.

One (LH) 47 uF Cap was bad with Meter after removal and other (Center Lower 47 uF) had broken leg. Board at Center Lower look like foil is missing and was difficult to solder. I am going to send it out. Is there any way to pull Engine running codes then?

AeroCoupe said:

ECU is telling you “nope”. Send it for a rebuild.

Click to expand...

Sent it to ECU Exchange in Florida and they did a good job. Looks like new and wrote note what they fixed. Got ECU in and found bad wire to MAF and O2 sensor needing replaced. All that plus base idle reset. Now runs good and no CEL.