%META:TOPICINFO{author="blundar" date="1077237440" format="1.0" version="1.1"}% OBD0 PR4 ECUs from the USDM (and JDM?) 1.8L B18A-powered Integra have some quirks:

• There are two versions of the ECU, each using the same circuit board. One uses an internal Pressure Atmosphere sensor, one is setup for an external PA sensor. This might correspond to the 90 / 91 split, although I'm not positive.
• The input used for ELD on most OBD0 MPFI ECUs is used instead for something power-steering related. (Vernon, please edit this and explain more.)
• AC input/output is presumably used for something else because most integras I've seen use a externally-mounted AC controller module.
• most B18As seem to have an oil temperature thermocouple. Not sure if this is fed to the ECU or to the AC controller (that also controls cooling fans)