OK, All, Let's view this as a mental exercise... If we assume that all sparkplug wires are installed in the correct order, and that the "backfiring" is into the intake manifold, I'm guessing that the problem is with the intake valve in the cylinder that stops backfiring when the wire is removed. I would guess the valve is not seating properly during the compression stoke, allowing fire back into the intake manifold. I am thoroughly confused by the high compression on that cylinder, though. Is there any possibility that the valve seals during the cranking for a compression test, but "pumps up" when actually running and doesn't seat? Would a broken valve spring do this? I'm as curious as Mike is! Any ideas? Joe Savard Lake Orion, MI |