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P0301 on 2011 GMC Sierra 5.3 annoying me

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Alright. So the P0301 code came on recently. Went out there and when I was inspecting the truck on cylinder 1 I noticed the plug was just loose by about a thread or two. I pulled the plug cleaned it and put it back in. Still got the miss while sitting at idle, so I swapped cylinder 1 and 5, and no change. Only thing I didn’t change on the two cylinders is change their spark plugs and coil with one another. I just had a brand new fuel pump, new fuel lines, and filter put in it a month ago and am wondering if that number 1 injector might be clogged or going out. I haven’t pulled it yet, that was going to be my last ditch effort was to pull that and see if maybe the injector had gotten dirty from the new pump since it now is able to push an adequate amount of fuel unlike before because the lines were rusted since this is the flex fuel and the stupid neck on the fuel pump was rusted. What’s your thoughts? I don’t have my autel to see if dig into it deeper, since I loaned it out to a buddy who’s now out of town. 

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10 hours ago, shakenfake said:

Sounds like you probably are about to have AFM failure

I checked the intake and exhaust rockers for play to see if any of the lifters may have collapsed. Cylinder 1 was fine, as was the rest. I changed plugs and wires and that seemed to do the trick. Next I’m going to change the cylinder 1 fuel injector or clean out the old ones by running some cleaner through them. I haven’t decided if I wanted to unhook the fuel pump relay and do the feeding of the fuel rail from the Schrader valve or just replace the injector. With all the rust, and contaminants they were in the tank, lines, and more it wouldn’t surprise me if the injector didn’t get clogged when the pump, and all the lines were replaced. 

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