I have dropped a JDM b16 into by 91 CRX si and have just started to hook up the wires and noticed on the drivers side of the engine bay the harnesses do not match. I think the helms calls these the sub-engine harnesses. I have not seen any documentation on this problem. The plug from the B16 is a rectangular six pin plug while the one from the car is a round 8 pin plug (see picture). I took the B16 from a wrecked CRX where the harness matches. What do I do?

HARNESS MISMATCH

 

you need to run your stock si harness. add in the vtec wires

 

This is the best way to do it. You have an Si. De-harness your B16, and throw on your Si harness, and simply add the VTEC wires. Easier said than done though.

 

Stock harness + wires

Its a tight fit it some places, and usually easier to string the harness on the motor
before dropping it in. You should have no problem though.

Something to note (assuming this is your first swap), is that the 91 CRX SIs had
an oddball sensor on the back drivers side of the intake manifold (fast idle valve),
which isnt used on most other motors. Once you swap on your stock harness, you
will be left with an extra plug since the b16a lacks this sensor. Just leave it hang,
tape the end of it.

 

dont forget the knock wire. i think theres total of 5 to run.. but im prolly wrong. knock, vtec, vtec pressure and ...? some one help me out.

 

5 total, but only 4 need to be run through the firewall to the ECU. The last one you missed is secondary O2.

The 5th wire is the GROUND on the Vtec Oil Pressure switch. This should be grounded out preferably at the same grounding point as the factory grounding point at the Thermostat housing.