Hey So I have a 2004 g35 coupe with 210000 on it, it had a misfiring so I replaced coil packs and spark plugs, nothing, so then I did injectors, again nothing still misfiring, so then I took it to Infiniti and they could not find out what it was but they found out that it was cylinder number 4 missfiring , I scanned the codes my self and I had a cam sensor code, so I replaced both cam sensors and crank sensor and reset the ecu , now it will only start up if it has been sitting for a hour or 2 and will die about a minute after. Before I did the sensors the car stayed alive fine but still was missfiring . Oh and it still has the missfire when it does start up. Please help!!!

 

Did you use Genuine Nissan sensors, or Hitachi sensors (the OEM supplier), if you used any other brand sensor that's almost guaranteed to be the main problem.

Do a compression test and leakdown test on all cylinders. You may have blown out a ring or something physically broken in the motor.

If that all checks out it's time to ring out the circuits for each wire for the cam and crank sensors as well as each coil pack (everything goes back to the ECM), I would also do a megohmeter test of those circuits to verify you don't have broken insulation leaking voltage out somewhere to ground.

Even if the coil packs are "new" swap cylinder 4 with a different cylinder to see if the problem follows.

Scan with an OBD2 reader, preferrably while it's stumbling but running, and check for any other codes.

 

So I double checked the driver side cam sensor that I replaced and it was not plugged in properly, the car now start up everytime with no hesitation and ideals fine but still has the missfire. It drives fine but is in limp mode sometimes. when I take it around the block a bunch of different codes come up but all of them goes away. So at this point I think it’s either timing or compression

 

Did you use Genuine Nissan or Hitachi sensors?

 

Yes I have a parts car that I took it off

 

Unplug cylinder 4 and inspect the harness and wires for damage. Compression test the block to verify all cylinders are within 10% of each other. Leakdown test each cylinder as well.

 

so I did a compression test and cylinder 4 is now sparking however, you can just hear the missfire no shaking or anything but then after you rev it , the car just starts to shake and will not go back to the calm idle, I did the compression test and all cylinders were at 150 psi other then 2 with were at 170, the ones at 170 psi the spark plugs were covered in oil (cylinder 3 and 5)