Fuel pressure and knocking?

[RacerRick]

if you have been running premium fuel for years the problem is carbon buildup on the intake valves. the extra detergents in premium fuels keeps injectors cleaner but the injector sprays on the hot intake valve and those additives build up and "glow" causing pre-ignition and pinging. the problem is called "christmas treeing" because the valve looks like a christmas tree with all the carbon on it! kits are available that hook up to a vacuum port on the intake and suck in the cleaner then shut it off and soak for 30-60 mins,while you wash out the TB with the spray.

 

[JimTMich]

we're getting there sort of..

Well I retarded the timing to 7 degrees. No longer pinging on premium, I filled up with regular today and ping city above 3000 at wide open throttle.
So, running 7 degrees, new fuel filter, cap, rotor, wires, plugs (ap25), new ECT, new IAT indexed, cleaned maf, flushed the coolant, and even ran some sea foam through the tank. I guess I'll try the Christmas Tree cleaner next.
Jim

 

[JimTMich]

ttt