My 1uzfe spits and sputters

[tetnt07]

I just installed a !uzfe from a 92 ls400 in my 92 sc400, in starts and runs fine except it seems to misfire under load, i dont know if its ign. problem or
fuel injection problem. its got all new spark plugs and wires and new dist. caps. it will rev to any rpm without droping out or missing, but punch the
throttle quick and it sputters, it allmost seems like its dropping cyls, when you floor it it kicks hard but feels like its not firing all 8. the old engine
used the -4434 ecu the new one uses the -4111 ecu so we had to do quite a bit of re-wiring. am i missing something?.

 

[stevechumo]

You could have used the SC ECU and harness on the LS engine after the swap. You only had to swap the SC oil pan to the LS block. That's what I did on mine. But if you changed to LS harness, then I believe you have to re-wire the harness.

Your problem seems like a fuel problem, but it could be something else. You can start checking the fuel pressure, fuel pump, and perhaps the injectors. Then you can move on to the ignition diagnosis.