problem child

I'm new to the forum and need some help. I have a 1990 N/A with a miss fire and potentially a dead cylinder. I already replaced the plugs and injectors I think it could be an issue with the coil pack or worst case scenario a flat spit on then cam from the previous owner also has a slight vibration. Any advice would be appreciated.

KSpakes87

Usually a misfire on one single cylinder is either Spark Plug, Coil Pack or Fuel Injector.

To test the coil pack and plug simply remove the coil pack and plug and insert plug into removed coil pack with the connector still hooked up. Then have someone start the car while you ground the side of the spark plug to the intake manifold. If it doesn't fire then it is either plug or coil pack.

To check if the injector is firing simply use a long screw driver and place it on top of the injector and stick your ear to the handle. It will be clicking if it's working. Compare to a known working cylinder.

If all three of these are working then it will be time to test the PTU. Here is the FSM on testing the PTU:

http://www.300zx-twinturbo.com/s.manual/efec/179.gif

If all of these things are working then it's time to start chasing down wires.

borini63

Check compression first.

KSpakes87

You will want to check compression, but not first.

Not to trying to argue with you borini63, but the tests I said to check are going to be the most likely for a dead miss on the z32. Compression test will come after identifying it is or isn't electrical. As the z32's are very prone to electrical problems and 90% of the time the problems are electrical.

problem child

thanks KSpakes I'll give them a try but will the link u sent help on an N/A considering its a link for a TT?

KSpakes87

Yes. The PTU is the same for the N/A and TT.

problem child

OK thanks