I'm experiencing a P0303 fault code on my 1997 Ford Expedition. I've already replaced all spark plugs, ignition wires, the coil pack, and the fuel injector for cylinder #3. Despite these repairs, the code persists. Are there any other potential causes or diagnostic steps I should consider?
Check engine compression, especially for cylinder #3. A blown head gasket or manifold leak could be causing misfires. Additionally, don't overlook fuel pressure — it's a common contributing factor in P0303 cases on 1997 Expeditions.
I've already tested the fuel pressure and confirmed it is within normal range. I also replaced the fuel filter. What should I do next to troubleshoot this issue?
now what?" I don't know maybe diag it!
Continue with a detailed compression test on all cylinders, comparing readings to cylinder #3. If other cylinders show significantly lower compression, that points to a mechanical issue like a blown gasket or internal engine damage. Please update your progress here for further discussion.
Yes, this issue is commonly reported in forums involving older Ford Expedition models with P0303 codes.