Hi! New to create account, but have received great information from all of you in the past.

Little history: 01 Silverado 5.3l V8, 137k miles, full synthetic it's whole life. Had lots of electrical problems in the past - code reader works sporadically for the past 10 yrs, 5 window regulators, replaced lock actuators, no fuel gauge, radio has a ghost (on and off by itself), blower motor resistor 3 times.

EGR valve cakes with carbon often. (fails emissions cuz check engine light is on and code reader won't work) Puffs smoke on startup - blow-by or valve guide seals? Loses oil and coolant, but the two don't mix in their respective places. Did the head gasket sealant thing in the radiator - no help. Replaced hoses, and I don't think the radiator is leaking anywhere. Smell antifreeze when heat is first turned on. Needs heater core is my guess, but not willing to take dash off and mess with refrigerant so I just deal with no heat.

So here is my most recent problem. Lost cylinder 6. Can definitely feel it run rough at idle and low speeds. Happened once before - replaced plugs and wires and it fixed it - about at 100k. Now the check engine light is blinking, and code reader happened to work and here is what I got:

P0171 too lean bank 1 and P0174 too lean bank 2 (repeated twice)
P0306 cylinder 6 misfire (repeated twice)
P0507 idle control system rpm high

Here is my guess. Whatever is causing the carbon buildup in the EGR valve is fouling plug 6. Thinking I need to have heads rebuilt. That would fix puff of smoke on startup if problem is valve guide seals, but what if it is blow-by? How can I tell the difference? I could see the system setting the idle rpm higher if it is only using 7 cylinders. Logical? That said, I also don't know about the lean situation, or what the difference is between bank 1 and 2.

Any suggestions on where to start?

 

Sounds like those heads are toast. Just like mine were. A buddy of mine had bought a cylinder head for his 2000 Chevy S10 2.2 from King Cylinder Heads. They had these GM 4.8/5.3 cylinder heads brand new assembled all new valves and springs. www.kingcylinderheads.com/ fixed everything up great and Im thinking this thing is gonna run another 100K now.