Bought my first PPV Tahoe

[Nutro]

Well, I bought a 2014 Texas DPS Tahoe with a 150K mile 5.3L yesterday and she's got a P0304 Cyl 4 misfire. I looked on the Carfax and called the last shop that serviced it. They said the trooper brough it in back in Dec of 2022 for a rough idle and P0304 code. They tried a new injector, new plug and new plug wire on that cyl. No change. They tried an upper intake cleaner, nothing. Cleaned the MAF and no change. It idles quietly with no strange ticks or noises.


That mechanic said he told the trooper that it was probably a collapsed AFM lifter so DPS retired it and now I ******* own it (Yay)
I need to get it home and pull the valve cover on that Pass side.

Do I:
Check/inspect the valve spring and if broke, replace it and send it?


Compression test that cylinder?


Yank the heads and AFM/DOD delete it then have it tuned?


If I go ahead with the AFM/DOD delete, I think I read that I can use a NON AFM 6.0L or 6.2L cam? I don't need a lope or anything wild, this will be a daily/kid hauler to the beach on occasion. What cam would y'all suggest?

 

[RichardCranium]

Even though you mentioned you tried those "new" parts, I've too many times had a bad coil or other electronic parts out of the box. I'd swap an injector from another cylinder, clear the codes and drive it. If it says on #4, swap the coil from another known good. At least you know those components are working on your vehicle, and it doesn't cost you a thing other than time.

I'm assuming the misfire is intermittent? How quick does the misfire come back?

 

[Nutro]

I haven't got the Tahoe home yet. I'm hoping to bring it home on Wed this coming week. I think my first plan is to pull the passenger valve cover and see if the valve springs are moving. Then compression test that cylinder. I have a few other extra coils and I have an extra set of plugs and plug wires to swap around. I'll hook up a noid light to make sure the injector plug is getting power. I'll check all the wiring for chafing for bare spots etc. If none of that checks out, I will probably just yank the top end and AFM delete it then get it tuned