Answer
Sep 03, 2025 - 09:08 PM
If you’ve already swapped the plugs and coil on that misfiring cylinder and the code’s still there, here’s what I’d look at next:
- Fuel injector – If the coil and spark are good, the next thing is fuel. Injector could be clogged or dead. You can try swapping that injector with another cylinder and see if the misfire follows it.
- Compression issue – Could be a burned valve, broken spring, or worn rings. A quick compression test (or better, leak-down test) will tell you if that cylinder's mechanically healthy.
- Wiring / connector issues – Check the coil and injector wiring harness. These Fords are known for cracked insulation or loose pins, especially near the back cylinders.
- Vacuum leak – Less common, but a big enough vacuum leak near one cylinder (like around the intake manifold gasket) can cause a misfire.
Of course, not much troubleshooting advice we can give you given the limited amount of information. But the service manual will guide you step-by-step with the diagnostics and repairs.
Perhaps if you could let us know which engine you're working with, we'll be ready to guide you to the right manual.
