Getting P0304 Cylinder 4 Misfire

[rah11h]

2003 Ford Explorer Limited 4.6 V8

Check engine light came on yesterday. Checked codes and getting a cylinder 4 misfire. Number 4 spark plug was loose. Remove #4 plug and coil and switched with #2 just to double check to see misfire moved to #2. All 8 plug and coil replace about 7,000 miles ago. Would a loose plug cause this?

 

[matsavol]

I'd say it can. Loose plug would leak causing low compression. Low compression is one cause for misfires.

After you put it all back together, did the misfire go away?

 

[rah11h]

Cleared the codes. Drove vehicle to work today. No new codes. Must have been loose spark plug. Its something new with this Explorer all the time.

 

[rah11h]

Check engine light came back on this morning again. Still on cylinder 4. If its not the spark plug or coil, what would be the next thing to check??

 

[steve6534]

Check engine light came back on this morning again. Still on cylinder 4. If its not the spark plug or coil, what would be the next thing to check??

The fuel injector for that cylinder is the next likely candidate.

 

[centex99]

Unless it's been raining every day and getting wet/shorting out on cylinder 4, I'd have to go with Steve's advice and check the fuel injector. You could likely swap two of those and try again as well... be sure to follow proper procedures since they're pressurized lines.

 

[rah11h]

I swapped the fuel injectors around and still getting same P0304 code on cylinder 4. What's next to check after plugs, coil & fuel injector?

 

[Explorer_PL]

Compression test.