When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 2003 F150 5.4 with 169K miles. It's not perfect, but it's been running great for the past several months. Drove it several times over the weekend without issue, then Monday as soon as I left the house I could tell it was missing. Drove it (without choice) for about 20 miles and by the time I got home, the engine light was on. I hooked up my scanner and it gave me codes of P0305 (Cylinder 5 Misfire Detected) and P0316 (Engine Misfire Detected on Startup). It also gave me a C1284 - Oil Pressure Switch Failure, but then with a note that it might not be valid.
Anyway, I picked up a coil pack and plug and proceeded to swap out cylinder 5 (driver's side front). As soon as I pulled the coil pack, the boot was dripping oil and there was oil in the spark plug "hole". I used paper towels to get as much of the oil out of the plug hole, then used my compressor and a rag to finish cleaning and drying it out. I installed the new plug and coil pack, and everything runs great again. Obviously, the oil caused the misfire!
There are no obvious oil leaks around the area, and the plug tip had a little gunk in the threads but was otherwise dry (see photo) - and still had the correct gap. Plugs had less than 20K miles on them. Had a misfire issue with cylinder 6 back in March and had a shop fix it while doing a few other repairs. They mentioned nothing about oil or anything. I actually pulled #6 again when changing #5 and it was dry.
Looking for thoughts on what could have caused this.
I have a 2003 F150 5.4 with 169K miles. It's not perfect, but it's been running great for the past several months. Drove it several times over the weekend without issue, then Monday as soon as I left the house I could tell it was missing. Drove it (without choice) for about 20 miles and by the time I got home, the engine light was on. I hooked up my scanner and it gave me codes of P0305 (Cylinder 5 Misfire Detected) and P0316 (Engine Misfire Detected on Startup). It also gave me a C1284 - Oil Pressure Switch Failure, but then with a note that it might not be valid.
Anyway, I picked up a coil pack and plug and proceeded to swap out cylinder 5 (driver's side front). As soon as I pulled the coil pack, the boot was dripping oil and there was oil in the spark plug "hole". I used paper towels to get as much of the oil out of the plug hole, then used my compressor and a rag to finish cleaning and drying it out. I installed the new plug and coil pack, and everything runs great again. Obviously, the oil caused the misfire!
There are no obvious oil leaks around the area, and the plug tip had a little gunk in the threads but was otherwise dry (see photo) - and still had the correct gap. Plugs had less than 20K miles on them. Had a misfire issue with cylinder 6 back in March and had a shop fix it while doing a few other repairs. They mentioned nothing about oil or anything. I actually pulled #6 again when changing #5 and it was dry.
Looking for thoughts on what could have caused this.
