2008 Equinox misfire issues.

[Jamesmk]

I am in need of help and looking for suggestions on my misfire issues. I have had this vehicle for many years and it has 200,000 miles on it. 2008 Equinox 3.4 engine. Within the last year I had misfire in two different cylinders. I replace the spark plugs and wires and eventually the coil pack which took care of that error code. Now I’m getting an evap error code p0449 and P0446. And from what I read, wouldn’t cause my issues? The car misfires and loses power under light to moderate load. I Don’t know if it’s related or not but, the little metal flap under the gas cap(fuel nozzle hole) must have broke off and fell down the neck, which restricts fuel flow into the tank. Takes 5 mins to fill the tank. It’s still a great car, I’m just at a loss. Any suggestions would be greatly appreciated! Thank you

 

[Jamesmk]

Update… today it drive normally, no misfires or chugging. I had it scanned again and now I’m showing P0327 knock sensor low voltage, Po301 cycl 1 misfire and P0455 evac large leak.

 

[Autoworker 74]

I am in need of help and looking for suggestions on my misfire issues. I have had this vehicle for many years and it has 200,000 miles on it. 2008 Equinox 3.4 engine. Within the last year I had misfire in two different cylinders. I replace the spark plugs and wires and eventually the coil pack which took care of that error code. Now I’m getting an evap error code p0449 and P0446. And from what I read, wouldn’t cause my issues? The car misfires and loses power under light to moderate load. I Don’t know if it’s related or not but, the little metal flap under the gas cap(fuel nozzle hole) must have broke off and fell down the neck, which restricts fuel flow into the tank. Takes 5 mins to fill the tank. It’s still a great car, I’m just at a loss. Any suggestions would be greatly appreciated! Thank you

This isn't much help but the little flap on the gas filler neck disappeared on my 2014 Equinox years ago. I assume it's laying on the bottom of the tank just like yours probably is. I have 69,000 miles and mine has never had any kind of miss.
I don't know if an 08 Equinox has a Crank Sensor but my 05 Chevy Lumina started backfiring and bucking terribly. It took a while to find it but a wire to the crank sensor had burned through and was intermittently shorting against something. The car was basically undrivable until it was found and repaired.
Great that you got 200,000 miles out of it so far.

 

[Sunvalleynox]

Mine did that I have a 08 sport it was the 5v reference wire from the ecm it’s soldered and heat tubing on it anyway the wire looks good from out side but it was shorting inside the union i had crankshaft codes service stabilitrac /traction control ,power reduced it would stall after driving for a block hope this helps out someone the engine wiring harness is really brittle and the connector if dislodged might not provide enough contact I pry the female end so the connector provides a tight fit also apply dielectric grease