04 4.8 silverado

Question

HI I have a misfire on cylinder 7, I've done a compression test and it was around 90,I replaced the intake gaskets,switch injectors,replaced fuel pump but the spark plug is still running lean.
Any help would be greatly appreciated.

Answer 1

HI there,

90 psi is pretty low compression and indicates there is an internal problem going on here. You can determine if it's a ring issue or a valve issue by adding a cap full of oil and retesting the compression. If the compression increases then there is a ring problem. If not, then there is a valve issue. Compare your readings to a cylinder that isn't misfiring. According to the spec anything below 100 psi is a problem.