Again, another system that most people eliminate. Unfortunately the purge system on the 98/99 flash ECU is NOT compatible with the 91-95 gen cars. The 96/97 guys are fine and don’t need to change anything.
The reason is the OBD2 purge solenoid is a duty cycle operation like the BCS and EGR solenoids. The OBD1 cars have an on/off type solenoid. If you just plugged in your flash ECU and didn’t disable this solenoid, you’ll notice a rather obnoxious clicking sound at idle. This is because the ECU is triggering it on/off like the OBD2 solenoid.
You have 2 options for a fix:
*Since the stock BCS is fairly useless, swap that solenoid in place of the purge and it will function just like on a 98/99 car.
*Use one of the Chrome Custom Pin Outputs. ***details in a later post***
If you eliminate this system you must switch bits 15, 14 and 13 off in periphery 2 to avoid a CEL.