I have no clue. Not one clue as to why my 90 RS convert with a rebuilt 305 TBI engine keeps giving me a code 43. I've changed the ESC module, and the knock sensor. Although i have found something very interesting. My block, or so i think it is my block, has been filled. Because while changing the Knock sensor not a drop of coolant came out. It was solid inside there. I have checked all the grounds they are good and solid. The only other problem i have is a faulty oil pressure gauge. Now i have test driven it and used a volt meter on the wire from the ESC module and got a solid 8 volts continuous. even when the car starts to retard the timing and giving me the check engine light. And another thing. When i disconnected the temperature switch at the intake manifold the car would not start. So I think the computer could have died. The engine isn't stock. It has flat top pistons, a vortec cam, and edelbrock headers. Now i heard TBIs can learn a new cam but would a code 43 be caused by too much compression. I just need some help.

Did you change the timing chain or valve train during the rebuild? These things can cause a false trigger on the knock sensor.