So I got a b18a1 block with a 94 b18b1 head and obd2 b18b1 intake manifold.

It's obd2 because the guy I got it from says he convert it to obd2. And I have the obd2a ecu p75 along with it

I was able to hook up my stock 96 ex harness on the motor (which fits perfectly fine) but there was some plugs left over. When I took it to a shop, the guys says I need to use the 2 peice integra harness. I keep telling them its possible to use the stock harness because its obd2 ready but they keep insisting that I get the integra 2 peice harness. Most likely they want a obd1 integra one.

So my question is: if I have the obd2 intake manifold from a 96+ then can I just use my stock civic harness? I have the p75 obd2a along with it and would like to keep it obd2

 

Use the stock harness, you can't use te two piece in your car. The left over plugs are probably VTEC solenoid (one wire square connector by the distributor), Vtec pressure switch (two wire round connector), knock sensor (one wire round connector on back if the block), intake air temp (around the manifold, two wire black square connector), CKF (3 wire connector by the crank), fan switch (two wire round connector by the thermostat housing). You'll need to bypass the CKF and run the fan switch wires to the two pin sensor on the back of the block. Also convert the two wire intake air temp sensor connector to the round style or use the ex sensor in the intake arm.