Code reader says P0307

The service engine light is on, got a code reader and it came up with this code. We replaced plugs, distributor cap, and light still on, car runs really rough, what should we try next?

P0307 indictes a misfire at cylinder #7.

Did you try replacing the spark plug wire for cylinder #7?


Yes we replaced the plug and wire for #7

Check the wiring/harness for the #7 fuel injector. Check the resistance on that injector. Swap the #7 with another and see if the misfire moves.

A compression test on #7 cylinder might also be a good idea.

Thank you, we will try it

Check to see if the fuel injector for cylinder #7 is working. With engine running, take a long screwdriver or a length of dowel and put one end on the fuel injector and place your ear on the other end to act as a stethoscope. Can you hear the injector clicking rapidly? Now do the same thing to another injector. Does the injector for cylinder #7 sound the same as the other injector?


Are you sure it has fuel injectors?? How do we tell?

Yes. It’s fuel injected. The code P0307 is an OBDII code. All OBDII vehicles are fuel injected.


Ok, but does it have 8 fuel injectors? My husband is used to working on our 88 pontiac GTA and the fuel injectors are all on top