I have a 1994 ford ranger 4x4 I want to swap another ford ranger engine to a newer one so I can use an obd2 scanner on it
which ranger engines above 1997 have good after market support

 

Welcome to the forum

OBD2 is related to the computer in the vehicle not the engine, OBD = On-Board-Diagnostics
1994 and older fuel injected Rangers used the EEC-IV 60-wire computer, it used OBD1
1995 and up Rangers use the EEC-V 104-wire computer, it uses OBD2
(just a heads up 1995 Ford OBD2 was not true OBD2 so can have interface issues with some scanners, 1996 and up were true OBD2)

Computers were added to control Fuel Injection

Main difference between the two is that the EEC-IV didn't have spark module inside, it was a separate module on the engine
EEC-V has a spark module built-in, also more sensors for better fuel economy and emissions monitoring

Changing 60-wire to 104-wire computers requires alot of rewiring, i.e. 40+ more wires added
It can be done, but not sure benefits out weigh the effort or cost
You can get OBD1 scanners

The engine doesn't care about OBD, just the sensors added to the engine are related to type of OBD
You could put a 1997 4.0l engine in a 1994 4.0l Ranger and just swap the intakes so wiring matched up

 

I would just swap out the entire motor as opposed to trying to adapt ODB-II to an older engine. Sorry for sounding like a cheesy salesman, but I am selling the 4L OHV V6 (including the ECU [computer + complete wiring harness] and a handheld Accel SuperTuner) along with the automatic transmission (5r55e) out of my 1999 Ranger. It runs great, the only reason I'm pulling it is I just purchased a supercharged SOHC 4L out of an 04 Ranger that I'm putting in my truck. Therefore, I won't need the engine that is currently in my truck.