2001 Expedition P0308 DTC

[ibconcha]

I was wondering what could cause a p0308 dtc code (misfire detected on cylinder 8)? I have changed the fuel filter, spark plugs were changed about 4months ago, and fuel pump was changed about 1yr ago. The vehicle will idle kind of rough, and when you first take off it will feel kind of shaky and check engine light will stay on, I also can at times hear a vibrating from the catalytic converter I believe every now and then. When it gets going a bit it seems to not be as shaky or rough. And also at about 50-60mph the check engine light starts flickering off and on, and really the vehicle seems to be running o.k. All this started overnight, I drove the vehicle and it was running fine, then parked it for the night, next day when I started it it was idling rough and before I made it a block down the road the check engine light was on. Any suggestions?? Thanks.

 

[blacksnapon]

I was wondering what could cause a p0308 dtc code (misfire detected on cylinder 8)? I have changed the fuel filter, spark plugs were changed about 4months ago, and fuel pump was changed about 1yr ago. The vehicle will idle kind of rough, and when you first take off it will feel kind of shaky and check engine light will stay on, I also can at times hear a vibrating from the catalytic converter I believe every now and then. When it gets going a bit it seems to not be as shaky or rough. And also at about 50-60mph the check engine light starts flickering off and on, and really the vehicle seems to be running o.k. All this started overnight, I drove the vehicle and it was running fine, then parked it for the night, next day when I started it it was idling rough and before I made it a block down the road the check engine light was on. Any suggestions?? Thanks.

You can have water intrusion into the hole causing a misfire. It would be more noticeable at cold start. Pull the coil and plug, use silicone dielectric compound inside the "plug wire", then reinstall a new plug and the coil.