Hello all. First time post here. In search of some tech help as my current problem has surpassed my abilities.
The problem child: 2004 Tahoe Z71 4x4 8th vin Z Flex fuel 5.3
We received the truck in non starting non running condition.
Recharged battery, Fresh gas and injector cleaner, changed all plugs and plug wires, replaced all 4 O2 sensors. This got it up and running. However it only ran well for about 20 minutes then it started running rough. Also backfiring....found a few pieces of the cat in behind the exhaust tip. We pulled it back in and started a month long ordeal.
Using Auto Enginuity software we pulled Code P0300. The only current code.
We found cylinder 6 and 8 bank 2 had misfires ( We are now showing misfires in cylinder 7 bank 1 as well).
Compression check showed the following :
1= 165 psi
2= 175 psi
3= 170 psi
4= 180 psi
5= 170 psi
6= 180 psi
7= 170 psi
8= 175 psi
Combustion gas leak test showed NO gas in coolant.
Fuel pressure 49 psi key on twice, 45 psi while idling, 49 psi at 1000 rpm
Crank shaft position sensor 5 ohm
Injectors @ 13.52 ohm
Vacuum @ 20 in Hg at intake port
No EGR found
Have ran propane around base of intake without any changes noted
O2 output voltage:
B1S1= 0.34-0.81
B2S1= 0.37-0.70
Fuel trim:
LTFT B1= 7.03
STFT B1= 3.13
LTFT B2= 7.81
STFT B2= 3.13
Status closed loop
Blue/white exhaust smoke
I will post some screenshots of the test as they are moving around a small bit.

Cold just started

Cold just started

Cold just started

Cold just started

Cold just started

Cold just started

Cold just started

Cold just started

Cold just started

Cold just started

After warmed up

After warmed up

After warmed up

After warmed up

After warmed up

 

Very new to this software

 

You didn't post if you removed the cat?

 

Cat(2) are still in place.