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Greetings, gang. I’m diagnosing a pretty severe misfire on an 03 Ford Expedition 4.6 V8 that has me a little befuddled AND disgruntled. Haha. Now, all I working with at the moment is the Torque Pro app until I save a little more for a high end scan tool, so I will include all the info I can. The Expy has an awful misfire, and it threw two codes (in the beginning). The codes were P0302 (Misfire Cyl 2) and P0316 (Misfire on Start Up). I took a look at the fuel trims and noticed they looked pretty lean, so I did a lot of the normal procedures that we see here for such an issue, but ultimately I decided to focus my attention to the number two cylinder. Now, the manual says that the passenger side is 1-2-3-4 (front to back) and driver side is 5-6-7-8 (front to back). I went to the number 2 on the passenger side and noticed an after market coil, so I decided to swap it with number one to see if the issue moved (as I’m a bit limited on testing a coil with 100% accuracy at the moment). Anyway, I cleared the codes and took it for a test drive. The engine light came back on, but the codes weren’t what I expected to see. The car now has a P0300 (Random Misfire) and a P0304 (Cyl 4 misfire). Now, I’m not quite sure how number 4 has the misfire all of a sudden and not number 1 or 2 unless the manual is misprinted in some way. It just threw me for a loop. Haha. The freeze frame data showed the following:
Engine Load: 97.25%
Engine Temp: 172.4 ‘F
STFT Bank 1: 10.94
LTFT Bank 1: 3.91
STFT Bank 2: 10.94
LTFT Bank 2: -1.56
Engine RPM: 3,633.5
Speed: 54.0602 activity is healthy, all coils and fuel injectors indicate equal contribution (as best I can tell without scope analysis), fuel pressure is well within speck, MAF functions perfectly, umm…what else did I check ? No vacuum leaks that I detected other than the possibility of the intake gaskets, which the fuel trims don’t really suggest at idle or increasing RPMs. I believe I even did a compression test. I checked all kinds of things that probably aren’t coming to mind right now, but I couldn’t pinpoint the problem that day. I don’t know. I got irritated with the stupid thing and haven’t even muffed with it for more than a week now. Anyone got any ideas ? If more info is needed, just ask. Much obliged for any assistance. 😀
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