JustCummin
Junior Member
Hey All,
I've read tons of similar scenarios to mine but nothing quite exact and wondering what to check next.
Recently purchased truck for son's first vehicle with 128k. The truck runs great after it's fired up. smooth throttle response, good power. But almost immediately after buying it truck started giving a p0308 code on cold start ups. Erased 1st one, 2nd one came on as p0300, but since then have almost all been p0308. After 2nd one I replaced #8 coil, no change, then all new spark plugs (all gapped .044), no change. Spark plugs looked relatively similar and normal. Definitely no major discoloration with #8 plug.
Then I went to compression, cylinders 2, 4, 6 at about 150, 8 is 135. Obviously still decent but something going on with 8. Listened close to valve cover, no ticking or knocking from the rocker.
Every time code hits, its between 100-350rpm. Once truck is warmed, code does not repeat until next day's cold start again.
I wouldn't think I would be seeing 135psi with a blown head gasket or broken valve seat, but who knows.
Where do the smarter minds than mine feel would be the best approach next? TIA
I've read tons of similar scenarios to mine but nothing quite exact and wondering what to check next.
Recently purchased truck for son's first vehicle with 128k. The truck runs great after it's fired up. smooth throttle response, good power. But almost immediately after buying it truck started giving a p0308 code on cold start ups. Erased 1st one, 2nd one came on as p0300, but since then have almost all been p0308. After 2nd one I replaced #8 coil, no change, then all new spark plugs (all gapped .044), no change. Spark plugs looked relatively similar and normal. Definitely no major discoloration with #8 plug.
Then I went to compression, cylinders 2, 4, 6 at about 150, 8 is 135. Obviously still decent but something going on with 8. Listened close to valve cover, no ticking or knocking from the rocker.
Every time code hits, its between 100-350rpm. Once truck is warmed, code does not repeat until next day's cold start again.
I wouldn't think I would be seeing 135psi with a blown head gasket or broken valve seat, but who knows.
Where do the smarter minds than mine feel would be the best approach next? TIA