Got a b18c gsr in a 99 ek hatchback. What obd2 ecu do I need

 

You need to find a obd2 p72 ecu. What year is you wiring harness? you will need to match that up to for example obd2a harness with an obd2a ecu, obd2b harness with an obd2b ecu. They use different locations of the plugs.

 

or he can get a OBD2A to OBD2B or vice versa conversion harness

 

this is true but it will be cheaper to source an ecu that matches the harness so you don't have to spend the extra $$ on the conversion harness.

 

Correct me if I'm wrong but don't the 99-00 ECUs use an immobilizer? So using the 96-98 P72 ECU might be a better option. Also I believe the OBD2 JDM ECUs although not having the immobilizer won't pass emissions.

http://ff-squad.com/ecu2/?page_id=76

 

i dont think jdm ecu's will pass emissions, you might also have to hook up knock sensor , both o2 sensor and have a cat in place inorder to pass emission with a usdm ecu in place

 

00-01 ecu's have the immobilizer you can't use obd2b. you'll have to find an obd2a ecu.

 

For smog/referee, you will have to use a 00-01 GSR ECU. These have the immobilizer so you will have to have the immobilizer removed:

http://www.hamotorsports.com/immobil...l-service.html

 

So I need a p72 obd2a ecu and I'll be set?

 

No, you need a P72 OBD2B with immobilizer removed. See above

 

i also believe obd2 ecu's look for crank positioning sensors. if your doing the cfk trick u should be fine.