Hi thanks for take time to help me. I have a 91 honda civic si and I just bought a 96 vtech sohc engine. Can you give a hand with what I need to hook up the engine and if I can use the ecu is on the car or if I need the the P28 ecu wich one I already have it.
Again thank for bother to see my request

 

As far as I can tell, you have to use engine harness and ecu from your 96 engine. You would have to convert to obd1/obd2? Forget when obd1 ended. But yeah. I never messed with sohc engines but I'd also check if your motor mount brackets in your engine bay line up with the 96 engines mounting points. Seeing that they're put in different cars, not sure if you need modified motor mounts or not

 

^^ NO

 

Engine harness from your STOCK 91 engine.
Modified with a jumper harness to OBD1. (using any other harness will not plug into your cabin harness)
The P28 ECU will run the engine decently, but since the Y8 was never offered with OBD1, it won't be perfect.
Chipping the P28 with a Y8 basemap will run pretty well. Take that in for a tune on a dyno for best results.

You will need to extend your wires for the fan switch. Your 91 has it on the back of the engine near the oil filter and the Y8 has it on the thermostat housing.
you will also need to relocate the IAT sensor into your intake arm. Your stock engine has it on the intake manifold and the Y8 has it inside the air cleaner box.

Also expect an idle issue because the Y8 does not have a FITV.

The driver side engine mount from the Y8 will not work in your 91. Use the one off your 91 and trim the timing belt cover to fit -OR- contact HASPort for a mount.

If you keep your 91 transmission, it will bolt up to the Y8 and you keep your stock mounts.
You can alternately use the Y8 transmission, but you will then need a mount kit as well as a hydraulic clutch conversion kit.

 

^^^this

 

I've seen people keep the engine harness so I figured they'd have a conversion harness from the ecu. My bad. Didnt mean to give false info. Just a ef or da with gray engine bay plugs is not obd0. So somehow they kept the engine harness. As for the ecu not sure if they went from obd2 to obd1 conversion.

Obd0 plugs are yellow clear

 

Well you CAN swap out the engine harness, but it's very labor intensive and you better be GREAT with wiring to rewire the firewall plugs/chassis harness to mate up.

You CAN do a an OBD2 ECU as well... but that is another can of worms. OBD2 uses a few extra things that OBD1 and pre-OBD (OBD0) do not. A couple of them being a secondary downstream O2 sensor and a pressure sensor in the fuel tank (needs a fuel tank swap).