I have a ls/v with a pr3 head.in a 91 hatchback.(obdo) my question is will a chipped pr4 ecu work with this and also work with one 02 sensor?

 

PR4 will not work. that is for obd0 or obd1 ls non vtec. The right way to go would be a p72 chipped for your application, if you ask me. a p28 will work too, but would need to be remapped before driving to something like a p72 fuel and ignition map.

The only way you can get away with using a 1 wire o2 is to go with a pw0, which is an obd0 b16 ecu, which no one really supports reprogramming anymore. trust me, its much easier to just go obd1 and install the 4 wire o2 than to track down a reputable tuner to tune a pw0.

p72 is the most correct, with a p28 being second best, then pw0 brings up the rear. a pr4 would work to drive the car, depending on how much else is done to the car.. but you will be hating life. get rid of it.