Listen my friend has a 98 ex accord motor in his 91 dx accord and the vtec is messed. all vtec related wires have been checked. car runs super strong till just past 5 grand (where vtec is suppose to kick) then it trips a code and the engine light comes on and it studders. currently checking fuel pump, oil pump, maybe car's wiring harness.looking for other possibilities. anyone has experence with this swap?

 

Which ECU are you using? Check VTEC solenoid and oil lines? Maybe not enough oil pressure?