[nissan_driver24]

rule of thumb when dealing with a misfire like what u're having right now. Check for spark since it's the easiest thing to do first. and since u replaced the wires and plugs and u're still having a problem check ur dist cap maybe it could be damage, you could also check the rotor but most likly its ok since 1 through 3 is still working.

if that's all good then check fuel, since the 1 through 3 cylinders are working properly, then u're getting good fuel pressure now the only thing to do is to check for voltage pulse with a test light or something in that manner even a dmm will work, if you have good voltage pulse then check the injector for continuity i'm not sure what the ohms run for stock 240 injectors but you can check the injector ohms on one of the 1 through 3 injectors to get an idea of what it's supposed to be. if u're not getting the right ohms reading then it's a bad injector.

I think u are having a problem with ur injector being stuck closed but check everything has to do with the number 4 cylinder and ur problem will show itself up.