I am having a misfire cylinder 6 issue also EVAP PO449 error. Replaced rotor, dist. cap, plugs and wires, all ACDELCO.
Replaced gas cap and vacumm hoses. Genuine ACDELCO cap.4.3l TBI 2001.

 

Can you feel a misfire, or is it only a SES light?

 

Doesn't feel like a misfire. Spark plug gets spark. Error comes up on hand held computer, also when operating temperature idles 500 rpm lower.

 

Mine idles at 550 in drive when warm.

If the "misfire" isn't felt and is not turning on the SES light, then it is not considered to be a problem. Pending codes showing on a scanner or some misfire counts in live data do not necessarily meet the criteria established as a real problem.

P0449 is the PCM recognizing an electrical control problem with the evap vent valve above the spare tire. As I understand it, it is fairly common for the wiring to the valve to get damaged on the driveshaft. Otherwise, use a scanner capable of cycling the valve, get a wiring diagram, and diagnose accordingly. Car Gauge Pro/BAFX OBD2 adapter will cycle this valve for certain as I have done it on my 2001 Blazer and 2004 Avalanche. Good luck.

P.S. 2001 is not TBI