I'm having to do the same in my 2015 Sierra 1500 with the 5.3L L83 motor. I went to eBay where they are selling refurbished OEM injectors. There compatibility chart said I was buying the right injector when I found out today from the dealer that there are 3 different injectors for this motor. I guess my first question is why? Anyway, I had a one in three chance that I bought the right ones. Well, I didn't. I did however get all 8 for $109.00 But now I need to ship them back and get the correct ones. Parts said there is a low, normal, and High flow injectors. Mine are the normal flow injectors. But there's more to this story.
First of all there isn't squat on the internet about changing these things. Some people have said the injectors are accessible without removing the manifold. Wrong! You have to remove the manifold and you need to replace the 8 intake gaskets when you put it back on. Dealer quoted me $5.76 each for the manifold gaskets. For a rubber rectangle o-ring. Joke! Anyway, I also heard you have to replace the fuel rails that the injectors are attached to. I was told that is not the case. All I need is the injectors and the gaskets for the manifold. If I buy replacement injectors from the dealer they are $156 each. The dealer code shows my cylinder 2 and 3 are misfiring. I figured I'd replace all 8 while I had it apart. But the way it's going I may just replace the 2 suspect injectors and get my truck running right again. It's terrible right now. Missing, surging, no power, horrible fuel economy. Kind of pisses me off. Especially since it only had 47k miles on it when it started having issues. I've seen several other threads with 2 and 3 year newer trucks than mine with half the miles doing the same thing. Maybe a problem GM? Anyway, I found a video on YouTube that shows a manifold swap on the l83 motor and it allows you to clearly see that the injectors are under the manifold, and under a thick piece of foam under the manifold. Video here:
So I'm going to find the right injectors and dig into this myself. My dealer quoted me $1075 to replace to stinkin injectors. So I'm going to roll up my sleeves and tackle this problem on my own. I don't need a dealer to rape me when I can do this on my own. Pretty straight forward. Probably medium skill and a few deep socket metrics and a wrench or two and I'll have this thing knocked out. That video helped me to see how it is laid out and looks under the manifold so I know what to expect. There is another post on here where a guy tackled it himself but used some strange verbiage about what parts he was removing so it was kind of confusing. Referring to the manifold as a plastic shield or something. But he was able to remove the manifold, change the injectors and said he did it all in 2 hours. So we'll see. Wish me luck. I'm going to try and post pics or do a video which seems to be long overdue. Help some other poor sap out that can't find any info on this seemingly secret process. I'll check back soon.
