Worn Valve Seals?

[Gturo_5.0]

How common is it for coyote motors to get bad valve seals? My cyl 8 keeps misfiring and fouling the plug. I changed the coil and nothing. At first i was scared it was my piston ring but the symptoms are pointing towards valve seals. The only time i see any smoke from my exhaust is a quick puff when i turn it on in the morning. Its also intermittent so it will be misfiring pretty bad and if i turn it off for a minute or two and turn it back on, it runs fine again. I think im burning a bit of oil too. So what do you guys think? Car has 92k miles

 

[me32]

What do you have done to the car? How are the coil on plugs?

 

[Gturo_5.0]

What do you have done to the car? How are the coil on plugs?

Has an airaid intake, throttle body spacer, and a 91 SCT tune, muffler delete. Coil packs have been replaced as well as spark plugs.

 

[me32]

Got any pics of what the plugs look like?

 

[Gturo_5.0]

Got any pics of what the plugs look like?

 

[me32]

Those do look really bad for sure. You have a 2011 5.0? How many miles were on that plug that you posted?

 

[TVSed GT]

Do the plugs smell like oil? Have you done a compression check? Are the coil packs oem or aftermarket?

 

[Gturo_5.0]

I dont know not many miles at

Those do look really bad for sure. You have a 2011 5.0? How many miles were on that plug that you posted?

Do the plugs smell like oil? Have you done a compression check? Are the coil packs oem or aftermarket?

Coil packs are OEM and the plug honestly just smells like gasoline mostly

 

[me32]

A compression check might be what needs to be done next