Thanks for reporting back.

 

Could have done a leakdown.

Is it normal for one of the valve to be worse than the other?

 

 

I left out one tiny detail in my recent update and feel that I should share it, in the event critics might tackle it as misleading results. I first did the dry and wet compression test. To ensure the later leakdown test results weren't skewed by "wettened" piston rings, I re-installed the plug and coils to then run the engine 10-15min, thus burning out the oil in the cylinders. Thus, the piston rings should have been in the normal "dry" condition when the leakdown test was performed.

This is interesting feedback. Out of curiosity, what do you expect to see from a third compression test? I've done two, weeks apart, and tested each cylinder multiple times those separate instances. I'd just like to understand your line of thinking.

 

 

Neither of those would work. Since the SS 2.0 is a direct injection engine, fuel is delivered straight into the cylinder. The coking occurs before the cylinder on the air intake side. Cleaners or gas don't ever pass through that area.
Most on the coking seems to come from the "dirty" air that is recirculated by the PCV system.
A catch can system to filter the PCV air would probably help.

 

Fuel injector cleaner won't help. These are direct injection engines, which means the fuel injector (and the fuel cleaner additive) sprays directly into the combustion chamber (i.e., the fuel spray never passes over the intake valves like engines from 30yrs ago; the spray over the valves had a secondary "washing" effect that prevented this problem). Higher octane gas won't help either for the same aforementioned reason (note though, the SS should be using high octane regardless). SeaFoam doesn't help either since the coking on the valves is pretty stubborn. So the only solution (except the band-aid mentioned in the following paragraph) is to walnut blast the valves about every 100K miles (or sooner if the problem arises)

The coking comes from oil vapors in the intake airstream that effectively "burn" onto the hot intake valve stems (imagine a burnt cake in the oven and the crusty residue left in the pan). This oil vapor is introduced by the engine's PCV system but is never thoroughly washed out due to the absence of fuel in the intake airstream. To address it, folks typically put a catch-can on the engine. Here is a link and another link about folks who have done it. There are 2 sources of oil vapor that can get to the intake valves, which cause the valve coking, 1) the line off the back passenger corner of the valve cover going down to the turbo, and 2) the hidden PCV valve inside the intake manifold. (the latter is harder to address) Both of these need addressed to fully fix the design flaw (I.e., oil vapor in the intake airstream without having a fuel source to "wash" the valves). The catch-can idea effectively re-routes these two sources out to a can mounted in the engine bay, that acts as an oil separator and then only allows clean air to go back to the intake valves (i.e., oil vapors remain trapped in the catch-can that you drain every few thousand miles; some sophisticated systems (more $$$) actually conveniently re-route the trapped oil back to the oil pan).

Hopefully this helps explain!