No power after swap! Horsepower that is.

Guys I'm so frustrated with how this whole swap has gone, I literally hate this truck! Here's the details tell me what you think. Ideas on what to do. Thx
4.8l with ls1 intake, 212/218 cam, long tubes, no cats 2.5 pipes to magnaflow mufflers, one of which I had on before the swap. Stock trans and converter with 90k and worked just fine before. Lots for ppl use this cam with stock converter and videos prove it sounds good, the lope i mean. Mine does not! It starts, runs/idles very good. Just doesn't sound like it has a cam??
The PCM has been basically mail order tuned, vats off and given specs of my cam. At LG Motorsports, a local corvette tuning place. Will no dyno tune cause no power? I mean this truck will barely go up my driveway. I plan on taking it back to them but I have to drive it there and I'm scared. Lol.

It should be a fairly stout setup, do you have any way to scan or datalog? Do the harness, pcm, and operating system match? Ive read where others ran into issues mixing car/truck parts.

My Mcheck engine light is off and on. I used a code reader and only got code for gas tank something cuz of my fuel cell. Never did that before swap. Engine and PCM from same truck, PSI standalone harness.

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.

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.

Make sure you have spark on each cylinder.

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.

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Originally Posted by dimebagged

Guys I'm so frustrated with how this whole swap has gone, I literally hate this truck! Here's the details tell me what you think. Ideas on what to do. Thx
4.8l with ls1 intake, 212/218 cam, long tubes, no cats 2.5 pipes to magnaflow mufflers, one of which I had on before the swap. Stock trans and converter with 90k and worked just fine before. Lots for ppl use this cam with stock converter and videos prove it sounds good, the lope i mean. Mine does not! It starts, runs/idles very good. Just doesn't sound like it has a cam??
The PCM has been basically mail order tuned, vats off and given specs of my cam. At LG Motorsports, a local corvette tuning place. Will no dyno tune cause no power? I mean this truck will barely go up my driveway. I plan on taking it back to them but I have to drive it there and I'm scared. Lol.

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I bet that was pricey. was it a new cam? which springs and pushrods? Nelson performance is your answer

Does the throttle body butterfly open up all the way? DBC or DBW?

Any exhaust leaks?

I have a aftermarket external pump going to the corvette filter. Slow94 I think that may be the rich problem.
Yes at LG it was $375, I could go back for the rest of tune but I don't have a trailor. Nelson was a choice but I went for local. Guy at my work had I send his PCM back 2 times to get the tune right.
I haven't checked how open the TB is, great idea.

I have a local tuner coming over next week. We will see what happens then?

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Originally Posted by kerrige

Any exhaust leaks?

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Yes a small one at the header outlet. I need a female adapter.
Thanks for all the ideas/ help!! Great site for these problems!

As long as the vette regulator is plumbed and working correctly, it should regulate 58 psi, so you should be fine there. If your tuner has a way to datalog, yall should be able to get it figured out.

Well I'm only running on 4cyl! Lol. Something wrong with the wire harness not getting ground to the left bank of coils. I don't know how in the hell I didn't notice this sooner.

Yep the ground wire had broke inside the coil plug. Removed, soldiered and problem fixed. Fired up and burned all the extra fuel out and runs great! Plenty of power now and sounds freckin in badass! Ill finish the tune and I'm done. Now I can update my garage thread soon:)
Thx for all the help