Chasing a rough idle?

[2009TahoeLT]

@2009TahoeLT
I had misfiring/rough idling caused by counterfeit spark plugs.
Here's the thread I did : https://www.tahoeyukonforum.com/thr...iring-at-idle-counterfeit-spark-plugs.146952/

I had thought about that but I bought them from rockauto. Not that they might not have counterfeit stuff come through but I’ve been very happy with parts through them lol

 

[2009TahoeLT]

Replaced the bank 2 upstream o2 today. No change. Cats are not clogged. Still misfiring on every cylinder over 1100 rpm and a rough idle. Did another smoke test, only thing I found leaking was the dipstick tube lol. Any other ideas??

 

[Fless]

The fuel trims are taking away quite a bit of fuel, trying to control the oxygen levels in the exhaust -- something seems to be causing too much fuel delivery. Do we know the fuel rail fuel pressure?

 

[Doubeleive]

connect a fuel pressure gauge and prop it up under the hood hinge so you can see it and see what it shows under a load (driving around)
should read about 44psi (running) 50~65 key on, engine off (cold). heat soak will/may make it rise if the engine is hot (key-on engine-off)