2014 5.3L L83 Fuel Injectors, AGAIN! HELP!

[FishinDVM]

Hey guys, 2014 1500 SLT A/T Sierra 5.3L L83. Last year (exactly 11 months ago) I was one of the people who started a thread on "add me to the fuel injectors list." I had 2 fuel injectors go at 87K miles. First is was a p050d and p0308, then the p0307 came. But the NON AFM was worse, cylinder 8 that is. So, I did a million things first (MAF, new coils, new plugs, etc) couldn't fix it... so to the dealership. They tell me needed 2 fuel injectors replaced (#7 and #8). Far more misfires on number 8 btw. So, I thought it would be covered, I was under 5yr/100k... but fuel injectors are specifically listed as not covered. I figure while there, just do all eight so I dont have to do this again. WRONG!

 

Now ever since that was done, I occasionally get a smell in the cab that is like a mix between gas, oil, exhaust... but I cant pinpoint it as exactly being either one of those, and its not all the time. I notice it sometimes at start up or idle. I had the local mechanic check for vacuum leaks and exhaust leaks upfront near the manifold and he said it was fine. I had no codes, no low oil, all fluids perfect... but every now and then I'd smell it. Fast forward in time... all was good for 11 months, now here I am last week, 12K later, at 98,900 miles. I get a p0308 and a p2099 (post cat rich trim bank 2). I hate the chevy dealership, so I take it to my mechanic to quickly rule out all the simple things, which he does, and tells me unfortunately he thinks its going to be involved (lifter, cylinder, fuel injector). So he told me to head to a local shop that strictly does engine work and was highly recommended by a few people I know. 

 

End story, they get the valve covers off and see the underside cover over #8 is all stained so what I was smelling occassionally was an oil/fuel mix being burnt... not a ton, but there. After taking the fuel injector rails off he calls me up. The #8 for lack of better words looks F***ed up, corroded, carbonized, discolored. The seals are either never there, broken off, corroded apart, whatever... but missing. He wasnt there when the chevy dealer replaced them last year. The problem he said, is that THE HOLE THE INJECTOR GOES INTO IS NOT SMOOTH. He says there is a ton of carbon build up in there, and he cant tell if its simply horrible carbon build up, or the metal itself is pitted, but if he tries to slide a new injector in, it hits resistance and the seals get all scraped up. He tried to clean out the hole with a bore brush per my request but to no success, it just wont accept an injector smoothly.

 

So he gives me a zillon options. He could force another injector in there and send me on my way (and yes its much cheaper than what the dealership charged) but since the seals likely wont seal 100%, I may have this issue again on the way home, 2 months, 10 months, who knows. I could go back to chevy under the assumption that whoever replaced it 11 months ago just didnt give a damn and jammed the injector in there and called it a day, but how can this actually be proven? and I may be paying a 3rd time to open everything up only to enter a financial/lawyer battle with GM. He said he could take the heads and everything apart, but its a ton of labor time in a 98K motor. Or we could swap out the engine, which sounds drastic, but add up the cost of possibly doing this a third time and you're already there... and the rest of the truck (besides engine carbon) is perfectly fine. I told him to make some calls just to see what was available and cost. Two engines nearby, one was a 2018 with 21K on it. Everything total would be $5200 engine, labor, and obviously what they did so far would roll in towards that assuming thats the way I wanted to go.

 

I know people can walnut blast the back of valves and such, but can the injector ports be adequately smoothed out, and is taking it apart and having someone do all that really worth it?

 

Is there a difference between the 2014 5.3 and the 2018 5.3??? Did GM change anything, like injector model for instance? What would you do at this point?

 

FYI... to be honest with you all... up til 55K miles I did oil changes with 0W20 mobil 1 full synth every 5k, ran 87 octane, occasionally let it go into v4, and did not run a catch can. After learning better, I started doing oil changes more frequently 3-4k, used 93 octane, M5 only, and an occasional Techron fuel inj cleaner in gas and still had this happen... but I came late to the party obviously. If I do go the engine swap route, I'll also add in the catch can to say I did everything I could going forward. Anyhow, thoughts guys? I got til Tues morn to take a plan of action. Thanks, Chris