daves21

-2013 Tahoe 5.3LMG 2WD PPV
I'm tired of it already being a parts cannon and trying to get to the bottom of my rough idle(no cel). I've just bought a 2013 Tahoe with 100000 miles on it, yes it is a ppv, but the previous owner got it from the police department at 26k(proved with carfax), really the only reason why I got it. It has brand-new coils,wires,plug,and maf. Long term fuel trims hold 2% and short terms are both the same and are not sporadic while driving, around 5-7%. I've have checked for vacuum leaks with carb cleaner but could not find any, I have fixed an exhaust leak at the manifold to cat but did not help. I'm starting to think the AFM is just going to crap unfortunately. No loud collapsed lifter tap, but just a normal 5.3 tick that you get on the passenger side valve cover. Now sometimes it will not let me put gas in it, I know the evap canister is bad but I have the replacement for it, and I doubt that would be the cause. I have just noticed today that my alternator might be going bad and is not putting out a constant 14v and fluctuates as I turn accessories on and off while I drive, and you can audibly hear the fan speed change from going from park to drive, I'm assuming because the RPMs change, even at 14v on the dash it still misfires at idle. Any advice, I mean any, would be a great help!! Thank y'all!

tech2

evap system could cause idle issues if the purge is stuck open.

get access to a scan tool that can monitor misfire data. with this you can determine what cylinders are misfiring. when you find that out, post back.