So im putting a b18c in my 99 civic ex i have the ex harness but do not know how to do the mods to plug it but i heard i can use the 99 si harness and it would just plug and play since obd2

 

Just use your harness as it's almost identical to the Si harness with the exception of the CFK plug and distributor plug. You'll have to do a few wiring mod depending on what ECU you use and if your B18C is OBD1 or OBD2. List those and we can help you on how to wire it.

 

its odb2 i just dont really know how to do the mods and ecu is p73-003 i think

 

Is it a JDM motor? Is it a JDM ECU? Is the B18C the type R engine or the GSR engine?

Can you post pics of the engine and the ECU including the label?

 

Yes jdm motor and ecu 97 spec integra type r can't post pics at the moment

 

Use your harness and get an OBD2b to OBD2a distributor adapter. As long as your ECU is JDM then you don't have to worry about the CKF sensor. For you intake air temp sensor you'll need to put into your intake arm. Check out this thread I made

https://honda-tech.com/honda-civic-d...-vtec-2987229/