Black smoke

[Antonio757]

I’m going to try to make this as detailed as possible in order to give the background history about my vehicle. I own a 2002 Chevy Tahoe with a 5.3 engine. I’ve been experiencing several different problems but I’ve corrected most of them. It started with a misfire in cylinder 4 and 8. 4 just needed the spark plug replaced but 8 was dead because oil was leaking from my valve cover onto it. I replaced the valve cover gasket and replaced the spark plug. Those issues were resolved. I also had a clog catalytic converter so I’ve replaced the exhaust system with new converters and a magnaflow street performance muffler set up. I also had all the O2 sensors replaced. Now I have black smoke coming from the tailpipe and the fuel efficiency is bad. From what I know this is a bad fuel to airflow mix. It’s also causing bad acceleration, and my truck stall out at low speed or when idle at times. These are what I've replaced so far- fuel pressure regulator, fuel filter, and coolant sensor. My fuel injectors are at a steady 55 psi and I’ve sprayed brake cleaner around the intake to reveal if there’s a leak and nothing. Hopefully this give enough information to give me some solid feedback. Thanks in advance!!

 

[afpj]

What brand of O2 sensors? You have any old data to share? Fuel trims, misfire counts etc. yes, I see that you corrected the misfire in 4 &8, but are you sure? Just trying to help, not question your work.

 

[Antonio757]

What brand of O2 sensors? You have any old data to share? Fuel trims, misfire counts etc. yes, I see that you corrected the misfire in 4 &8, but are you sure? Just trying to help, not question your work.

It was boush sensors and the code went away after they were replaced.

 

[afpj]

Any obd data like fuel trims?

 

[Fless]

Absolutely need to see short- and long-term fuel trims, both at idle and about 2k rpm.

Fuel rail pressure when the engine is idling should be in the mid 40s -- say, 43-45 psi. 55 psi when running is way too much. Suspect the fuel pressure regulator, but do a KOEO pressure test.