No power after swap! Horsepower that is.

[slow94]

Have you pulled and read the plugs? Or can you tell if its dumping raw fuel out the pipes? Or maybe misfiring? I did a 5.3 swap a few years ago and that engine had been sitting long enough for the injectors to stick, it sputtered, popped, and fouled plugs, stuck a set of pullout injectors in and its smooth as glass.

Just for reference, it was a 94 short bed, stock lm7 with tsp224r, stock 4l80e, stock converter, 3.42 gears and tune. No track times, but the one time I raced a buddies 2002 short bed 5.3l, tune, 4.10s, etc, it was a bloodbath, probably put 7-8 car lengths on him and we were spinning on the launch and had to let off.

[dimebagged]

Yes I noticed some dark oily/fuel from the left header. Just pulled plugs and they don't look new, which they are. Left side looks worse than right too. I not a mechanic, but a good parts replacer. Injectors are used camaro stocks. Smells like raw fuel when running. Maybe they cranked the pressure up? If that's possible.

[gagliano7]

Make sure you have spark on each cylinder.

[slow94]

What's your fuel delivery setup? I think ls1 fuel rails should be preset to 58 psi, at that psi ls1 car injectors should be 28 lb per hour. If your pcm is tuned for a truck it could be set at 24 lb per hour injectors making it rich. If you can I'd verify fuel pressure, check for misfires, and pull those injectors out and get them cleaned. You should be able to see the gunk on them if theyre blocked.