1998 Ford Expedition Eddie Bauer review from North America

Battery died while camping.

The number 4 cylinder started misfiring.

To all,

I have a 98 expedition EB, 77k, 5.4 motor. I was recently on a trip and got the check engine light, flashing, after going over Donner pass, 7,000ft or so. Had the wife look it up and it talked about possible misfire or something with the catalytic converter. The SUV was running OK at the time I thought. After about 15 min the light would go off for a min or so and then would come back. Then it would go on steady. Of course the book says steady could be the gas cap not on tight, etc. After about 20 min I noticed the Ford running rough and could feel the misfire, especially between 1500 and 2000 rpm. We were only three hours into a 7 hour trip so we stopped in Sacramento and holed up for the night since it was Sun and no garages open. I did as much research on the web and armed myself with as much knowledge about the light. I want to say thanks to all who have posted before me, you really helped! In my research I found the following possibilities:

1) If the engine is running rough and smoky exhaust, fuel injector stuck open pouring too much gas in

2) Possible fuel filter dirty or problem with (?) fuel neck

3) Oxygen sensor, water or fuel dripping on it possibly messing with mixture (cold weather and water unfreezing or lots of rain

4) EGR sensor (Exhaust Gas Recirculation) or valve. Related is the DPFE or differential pressure sensor related to EGR operation

5) Fuel tank pressure sensor

6) water in the spark plug

7) a blown fuse

8) vacuum tube leak near intake manifold (we did find one soft PCV (positive crankcase ventilation) tube near it, but don't think this was the cause.)

9) Idle Air Control valve or IAC

10) spark plug or spark plug wires or bad coil or coil pack

11) loose gas cap.

After checking the OBD or on-board diagnostic code we got a P0304 which is #4 cylinder misfire, i.e. #10. Changed both the spark plug and the coil and all was well. Finished the last 500 miles without a hitch. In a lot of postings Autozone was talked about as being able to read your OBD codes for free. This turned out NOT to be the case at the one Autozone I tried. The employee said they weren't allowed to read them in California. Not sure how wide spread this is, but you supposedly can buy one on ebay for approx $45. I think the coil was the prob, the spark plug looked OK, but the coils are advertised to 100k miles, 77k was close. I would recommend calling autozone or other parts stores or garages to see if they will read the code for free. The coil and plug were about 100 bucks plus an hour of labor and change for $184 total. Add in the 116 hotel bill and I got out of it pretty good. I hope this info helps someone else out, I've now read too many "check engine" light horror stories. BTW Bob's Auto Service in Elk Grove, CA did a great job, they specialize w/Ford.