Hi Guys,

Post is for a 2006 XLR-V, but since there is basically no support for this vehicle, I turn to my corvette brothers! Flashing P0300 engine code

Car is suffering from a BAD misfire, as in shaking violently and making knocking noises at idle. As far as I can tell all cylinders on the drivers bank are misfiring randomly.

I've:

Replaced all coil packs
Tested injectors (can hear clicking)
Completed compression and leak-down tests (Normal for an old tired supercharged Cadillac ) 125,125,125,130,140, 110, 125, 130
Tested fuel pressure
Replaced Spark Plugs
Tested for Vac leaks
Cant smell any fuel out the exhaust, exhaust "puffs" seem normal.
Oil looks good, no blow-by coming out of the valve covers, no air in coolant system.

What I haven't done:

Tested coil harness for ECM fire signal.
Tested physical injector flow

Unplugged individual coil packs and coil banks to try to isolate. Disconnecting ENTIRE drivers side coil bank barely changes idle, disconnecting passenger side coil bank immediately kills engine (this is what leads me to believe its an entire driver's side bank issue)

Both banks threw a P0420 Catalytic threshold code a year ago, but I disabled the report in HPtuners.

Car STINKS like exhaust, like water your eyes bad while driving. Which leads me to the core of my question, is it possible that the drivers side cat converter is so damaged/clogged that it is causing a cylinder bank random misfire and purging exhaust into the engine compartment? These cars have the cats built into the manifold so I'm thinking about just cutting a hole in it and removing the guts. Am I way off base here?

Thoughts, criticism, and oversights welcome.

Thanks.

-Kevin