1G Dead Cylinder

[Db_datsun]

Hello everyone, I'm stumped my cylinder #3 is dead. I checked compression which all cylinders came back good, checked the resistance on the injectors as well as made sure all the plugs to the injectors have power, verified injector #3 plug works on other injectors, verified fuel flow, verified timing, swapped plugs on coil pack batch. When removing plug wire or injector wire the engine doesn't stumble at all, when removing any other cylinders plug wires and or injector plug the engine stumbles.

 

[dwb]

Swap your #3 injector with another cylinder and see if the issue moves.

 

[Db_datsun]

Swap your #3 injector with another cylinder and see if the issue moves.

I have and the issue did not move.

 

[dwb]

Have you verified spark on that cylinder? Does #3 spark plug look/smell wet with fuel?

 

[Db_datsun]

Have you verified spark on that cylinder? Does #3 spark plug look/smell wet with fuel?

I verified spark, not wet with fuel

 

[pauleyman]

Did you verify the number 3 injector harness is firing? Thats about the only thing left if you are sure you have spark.

 

[Db_datsun]

Did you verify the number 3 injector harness is firing? Thats about the only thing left if you are sure you have spark.

Yes, checked the voltage and it worked on inj #2

 

[pauleyman]

Yes, checked the voltage and it worked on inj #2

Not sure that's quite the right path. 3 is dead. 3 has spark correct?. Is 3 firing the injector? Sounds like it isnt and you need to find out why. Id start with the harness at that injector

 

[Db_datsun]

Not sure that's quite the right path. 3 is dead. 3 has spark correct?. Is 3 firing the injector? Sounds like it isnt and you need to find out why. Id start with the harness at that injector

The injector for that cylinder has been swapped with another know working injector, the result is the same cylinder #3 is dead, the connector is showing voltage, when inj #2 is unplugged the engine stumbles as expected, when inj#3 connector is plugged in to inj #2 the engine no longer stumbles, this was done as a piece of mind check, spark plugs have been swapped, as well as the spark plug wire to the other paired post to no effect

 

[19Eclipse90]

Voltage at the injector plug is one thing.
The ECU grounds the other pin (check your diagrams or determine which pin goes to your injector resistor pack via wire color or continuity test; the wire that does not go to the resistor pack would be the ground wire) when required based on the other inputs to the ECU, causing the injector to open. All of that in detail here: 1G basic ECU MPI relay circuit function

If that’s not happening, you’ll have a dead cylinder. Make sure that your “ground” wire from the injector to the ECU is good and that the pins on the injector connector are well seated and making good contact when engaging with the injector. If you can verify all that, problem lies in the ECU.