I have a 2004 Silverado 5.3 4wd that I am working on. My buddy brought it to me to fix complaining of a lack of power, excessive white smoke/ soot from the tailpipe, an odor to the exhaust
and a flashing check engine
light. I put my code reader on it and
found a bank 2 sensor 1 o2 sensor code, misfire code, and a bank 2 lean code. I put in a new oxygen sensor at that location and noted that the sensor I pulled out was caked in soot. After clearing the codes and driving the truck it now has a lack of top end
power, misfire at high RPM. When I give the truck heavy throttle and wind the engine up to say 4000rpm and up the check engine light will flash and I can hear detonation. My code reader says that there is a P0101 and P0300 code pending. I replace the MAF sensor,
but it made no difference. I suspect that the CAT is majorly clogged on the bank 2 side that had the bad O2 sensor. I put a pressure gauge in the upstream bung to measure backpressure and am getting about .5 psi at idle and 2.5 psi at 3500 RPM. What is the
spec for backpressure spec / procedure for measuring it on this truck? I am going to rerun that test and do it on Bank 1 as well to compare. I also want to check the fuel pressure to rule that out.