I was on the highway yesterday when my truck started to flash the check engine light and shutter really bad in overdrive. It also sounded horrible, like it was spitting almost. Spark plug number 8 was just gunked in oil, I haven't done the plenum on it yet, because I snapped one of the intake bolts when i went to do it, and said screw it, threw it all back together. I replaced the spark plug but it is still misfiring. My question is, could I use seafoam in the intake to clean out a lot of that oil in there just to hold me off until I can get everything together to do the plenum the right way? TIA

98 1500 with a 360 4x4.

 

You can try it, but, don't feed it too fast..... hydro-locking the engine would just be bad.

Also check the PCV system, if there is oil in the tube between the valve, and intake, replace the valve. Genuine mopar please, they are actually the correct flow rate. (and less than ten bucks.) Valve guides are another source of oil in the cylinders. Given your truck now qualifies as an antique.... they are likely toast.

 

Well, I tried seafoam and a mopar PCV valve/tube. It sounded a little cleaner, but still horribly misfiring so I did a compression test on cylinder 8.....Time for a new engine lol. Found one locally with 77k miles so I'll probably go with that. Thank you.

 

That bad huh?

 

Cylinder 8 has no compression at all.

 

Broken valve spring? Stuck valve? Gotta bore scope? Might have a look and see if anything obvious presents itself.