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P0354 Ignition Coil Fault in 1998 Ford Expedition 5.4L V8 with 4WD and 94K Miles

Model: 98 Expedition Fault Code: P0354 Posted: 2006-04-10 23:18

I'm experiencing a P0354 diagnostic trouble code on cylinder #4 of my 1998 Ford Expedition with a 5.4L V8 engine, automatic transmission, and 4WD. The issue is located in the rear cylinder, making access extremely difficult due to tight space and significant mechanical interference. After removing multiple components, I was able to replace the ignition coil. However, symptoms persist: poor idle quality, lack of power during acceleration, and the check engine light returning after clearing. Fuel pressure readings show 30 psi at idle, rising to 40 psi when the vacuum hose is detached—within normal range. A friend suggested replacing spark plugs, which I find frustrating given their age and the difficulty of access. The original ignition coil reading was .5 ohm primary and 5490 ohms secondary—both within expected values. Despite this, the code remains active. What should I check next to resolve this issue?

Related fault codes
P0354
Comments (3)
Anonymous 2006-04-11 06:49

Try swapping the ignition coil with one from another cylinder—ignition coils on older Expedition models are a common failure point and may be defective even if readings appear normal.

Anonymous 2006-04-11 12:04

At 94,000 miles, it's likely time to replace the spark plugs, especially if they have never been serviced before. Worn plugs can cause misfires that trigger P0354 and other related codes.

Anonymous 2006-04-12 08:55

Thanks, Jeff. I will need to build up my motivation to tackle the spark plug change.