i assume that you have a DOHC ZC? what model is the car? if it is one with DPFI, you will need to convert the wiring to MPFI, using the engine harness that came in your car - your flywheel, clutch, etc. will bolt right on
to swap the OBD1 DOHC ZC into the OBD0 88-91 car, first you need to decide whether you want to run it OBD0 or OBD1 - running it OBD0 is a little simpler than running it OBD1
there are a couple of things that need to be done for running it either OBD0 or OBD1 - first, you need to swap the engine mount from the driver's side end of your block onto the ZC block - next, you need to make some wiring changes to your harness - this is in addition to other wiring changes required if you have to convert to MPFI - the cooling fan switch is on the thermostat housing on the OBD1 engine and is on the back of the block next to the oil filter on the OBD0 engine - you need to remove the connector from your engine harness (big round black boot with yellow/green and black wires), lengthen the wires so that the reach the thermostat housing and install the connector from the ZC engine harness - you will need to rewire the distributor connector - what needs to be done depends on whether you are going OBD0 or OBD1 as well as whether the car is presently DPFI or MPFI - you will need to change the connector for the alternator or you can use the alternator from your engine - using the alternator that is on your car now will mean that you also have to use the 88-91 Si crank pulley - the 88-91 alternators use a 3-rib belt where the 92 & up use a 4-rib belt - all of the rest of the connectors plug right in - second, the OBD1 engine has the MAP sensor on top of the throttle body and the OBD0 engine uses a firewall mounted MAP - you can use either, but i would unplug the connector from the MAP on the firewall and plug it into the MAP on the throttle body - you will have to extend the wires to get the connector to reach - those are the things that need to be done in any case
to run it OBD0, you will need an OBD0 88-89 Integra distributor and 88-89 Integra Cylinder Position Sensor (on the end of the exhaust camshaft), along with a JDM DOHC ZC PM7 or 88-89 Integra PG7 ECU - if your car is presently MPFI, wiring the distributor is the same as if you were installing an OBD0 ZC in the Si, meaning you need to swap the distributor connector for one from a DPFI engine and extending the wires to the Cylinder sensor - if the car is presently DPFI, the DPFI distributor connector will plug right into the OBD0 DOHC ZC or 88-89 Integra distributor - the Cylinder sensor wiring is part of the MPFI wiring changes - you will need to either, swap OBD0 injectors onto the ZC and add the injector resistor box (if it is now DPFI) or you can remove or leave out the injector resistor box from the circuit and use the OBD1 injectors - this is all that needs to be done to run it OBD0
to run it OBD1, you need an OBD1 ECU - factory ECU is P29 and still uses the one wire O2 sensor - using any other ECU, you will need to add a 4-wire O2 sensor - you will need an OBD0 to OBD1 ECU jumper harness from someone like Rywire, Boomslang, etc. - you need to use the OBD1 distributor and the distributor connector from the ZC harness and swap it onto your harness - again, you will need to do the same thing for the injectors as you would for running OBD0 - that is it for OBD1
