2008 Silverado Cylinder Misfire (help)
 

Hello all, I have a 2008 Chevy Silverado 1500. It has developed a misfire in cylinder 8.. I changed plug wires, moved coil, moved injector. Still misfires on cylinder 8, it’s not constant, but getting worse. I’m assuming a lifter or cam. Anyone else have any thoughts?

Well, I have fixed it.. It was a simple fix.. and one I wouldn’t even have agreed with prior to it solving my issue..
As I mentioned previously.. I moved the coil, moved the injector, replaced plug wires, replaced plugs.. changed intake gasket and still had a misfire.. cylinder 8 was always wet. A friend that builds high end engines told me it was a lifter, but I wasn’t convinced because it wasn’t constant.. another friend that owns a shop told me he would just buy a new engine and drop it in. (As it is a common issue) I wasn’t sold on anyone opinions at this point..

finally, before spending a grand on parts I decided to make one last attempt.. I seafoamed it.. and I seafoamed it hard! I used the seafoam fog and I used 4 cans of seafoam in my tank, and never put more than 3 gallon of gas in it.. (it was 2 cans of seafoam with 3 gallons of gas) I drove it hard and finally.. the check engine light went off and it started running smooth as silk. It doesn’t smell of fuel anymore, it idles perfect and it doesn’t shake or miss at all.. IT has now ran perfectly for 3 days..

I assume it had a ton of carbon in it from all the oil in the intake.. time to upgrade the valve cover..

moral of the story.. before tearing it apart.. put a bunch of seafoam in it..