ok so my gf bought a hatch a while back with a b16a2 swapped in only problem i can see it that the guy used a p75 to run the car so it has a cel and oil pressure light pressumably for vtec, it runs fine but ive tried a p28 and a p72 yesterday and neither computer will turn the car over, im thinking it def has to do with the way the wiring is. im unsure of the diagrams for the underdash and ive searched around a bit but not a whole lot of luck. can anyone point me in the right direction.

 

I'm most concerned about the oil pressure light. Is the engine oil low? Also pull the CEL code(s) as I don't think the P75 would be looking for VTEC. Do you have an OBDII P75 whereas the P72 is OBDI like the P28?

 

good point on the cel. no the engine oil stays very steady and the car runs great but of course its in limp mode since the cel is thrown and no vtec becuase of the ecu. no its an obd1 ecu.

 

Unless your oil pressure switch circuit is bad, illumination of the oil pressure light suggests low oil pressure and possible a bad oil pump. Don't run the engine until this problem is resolved otherwise the engine may be destroyed. Also pull the CEL code(s) as described here.