MrPink
Bainisteoir Páirteanna
I am the opposite of your boy, I like the GMC grille more. I may do the GMC grille with the Mexican Chevrolet Emblem but unsure.
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I had a feeling it wasn't a vacuum leak, but at least you can now rule that out.
Not likely a bad MAF because, like you said, that would affect both banks. Do you have a DVOM with Hertz function? You can check with that, or look at the MAF values on your scanner.
I find it puzzling you aren't getting any codes. My 5.3 truck is running at around 11% LTFT both banks and the check engine light is on. Sometimes it goes away, but it comes back on. It runs fine though. Related to that are some O2 sensor voltage codes. My O2 are okay, because I didn't have any codes before the engine swap.
You you have a test light? Check the injector connectors for pulsing, specifically the lean bank. The light should blink when the engine is running. I think noid lights are the proper tool to do this with, but I've done with a LED test light and it works just fine.
Otherwise, I'd would be double checking the tune.
Sounds like a plan. What codes do you have?
Can you not disable individual injectors with the motor running in HPT? You haven't even scratched the surface of tuning, throwing in the towel for what seems like a mechanical issue would be foolish.