This is gonna be detailed, so you can understand whats going on.
My Buddy and I came across a 1990 std hatchback civic, that had been sitting for 10 years. Gave a 5 speed 1991 Dx tranny for the car. Well, we swapped in a b20 from Osaka. The car was converted to MPFI and was running fine on a LS Integra P75 ecu for like 6 months. Then there was the decision to go b20/vtec. He used golden eagle 84mm b20/vtec head gasket, ARP b18C head studs, Earl's Ls/vtec lines. The head is a bone stock obd0 (I think 89') b16 head, with stock cams BUT with skunk 2 Pro Cam gears set at 0,0. The head was supposedly shaved 10 thousandths when the Oil supply hole was tapped, by a machine shop. Head has Skunk2 Pro series intake Manifold with a stock obd2 B16 (00'Si) Throttle body. We are using b20 obd2 injectors, with no resistor box. An OBD1 block-off block is being use the resistor box's place. Car is using an OBD0-OBD1 jumper harness, not sure the brand but it came with extensions for the 4 wire 02 and Vtec pressure switch and solenoid. He opted for a phearable.net P28 chip, with a b20/vtec basemap. His P28 ECU was pre-socketed when he bought it from a guy.
The Car was throwing a few codes, I don't know them cause I wasn't there. He told me he got all the codes fixed. I came over there, and the car was idling fine. We went up the road with it and it felt like a Single Cam. I thought it was the ecu, so I told him to plug in a virgin p28. Plugged it in, and the car acted the exact same. So, thought we figured it out, the chip was bad right. Nope, got a obd1 p72 (GSR) ecu and the car runs the same. It throws of course code (23)knock sensor now, but also is throwing a code 43(fuel supply system). Ive never had a car throw that cel. So, ???. I just thought I would post on here for some help, cause I know someone knows whats going on. If anyone needs any more info on the setup/problems/car, let me know. Thanks for any PROFESSIONAL help