Hey guys, complete newbie here. I did an LS swap into my 93 c1500, just a 100% factory 5.3 swap. I made a stand alone harness and only tuned VATS out of the P59 ECM but I cannot get this engine to run or idle. Sometimes it will fire and I can pedal it for a few seconds but then dies, plugs are soaked and its flooded. VCM scanner shows my injector pulse width is through the roof, sometimes 50+ms and commanded AFR's as low as 3-4. I've tried playing around with some tables but can't get it to run. I downloaded a stock tune file off here and used the compare function and cannot find any differences between the two files.
I am waiting on a different set of exhaust manifolds to complete my swap so for the time being I am using open truck manifolds with only the passenger side upstream o2 sensor connected via a 8 inch section of pipe, driver side manifold runs to close to the frame to get any pipe with a o2 bung connected. I don't think this would cause this issue, I had another vehicle with a gen 3 5.3 (stock silverado) and unplugged all but its passenger side upstream and it idles, just not too happy.
I attached two files, one file is when the engine did fire for a few seconds and die, the other is me cranking it when it is flooded. Any help would be greatly appreciated, this truck has taken up my garage for far too long.