Bad o2 or bad cat?

[crownvic31]

The upstream O2 activity looks okay, at least for the time being.

Can you show us your short- and long-term fuel trims, both banks, at idle and at 2000 rpm?

What is the MAF reading (in g/s, please) at warm idle?

EDIT: the downstream bank 2 O2 sensor reading is a bit difficult to read since I can't see the whole graph. But by and of itself that O2 sensor wouldn't be the cause of the rough running. Might be an issue with that cat, though, if the sensor is good. You could re-graph, then swap the downstream sensors side to side and see if what looks like a lot of activity by that sensor follows the swap.

 

[Fless]

I don't really see anything wrong with any of that data. Not seeing anything obvious. Others might have a different view.

However, the fuel pressure seems high to me. If my conversion is correct, 399.x kPa is about 57 or 58 psi. I thought the regulated fuel pressure in these was in the mid 40s, but I don't know the GMT900 stats.

 

[houstontaylor]

On my 2003 Tahoe I had a vacuum leak sound in the same area. It turned out to be old, split vacuum hoses from the valve cover at the rear to the intake manifold on top of the engine (pcv system). Pick up on the hose at the rear and see if it is loose since the insulator covering can obscure a split. Also, my fuel regulator vacuum hose was split in a couple of spots in the same area of the engine.

 

[crownvic31]

Ok so i went at it today. Sprayed a can of brake cleaner to the driver side engine bay all around the intake manifold area and the pcv area and nothing. Also did another smoke test and nothing. Everything is sealed good.

So now im at lost.

 

[petethepug]

These motors are susceptible to carbon build up on the intake, pistons and T/B.

If you haven’t yet, verify your plugs are in good nick, replace the plug wires if due. They get damaged when removed. Run a sea foam or equivalent, clean the T/B butterfly and go through the procedure for it to relearn.

 

[crownvic31]

Another video parked and rpms at 1k and increasing to 1500.

 

[j91z28d1]

Another video parked and rpms at 1k and increasing to 1500.

what as then issue again? it's running badly?

the long term is adding fuel, so it thinks it's lean, the fuel pressure reading doesn't look correct. probably a scanner thing. the timing at 51 deg at idle seems odd. I seem to remember most ls idling much less. unless you have a tune?


pulled plugs and looked at them?

 

[crownvic31]

I have a blackbear tune with volant cold air intake, long tube headers, magnaflow high flow cats, new spark plus and wires, new oem fuel pump with all brand new oem fuel lines from front to back, all new oem evap system with all new lines. Everything has been running good. This just start suddenly.

Mpg are super low, running alittle rough. I did sent a datalog to blackbear in hopes he can see something.

 

[crownvic31]

If i remember correctly, the only thing that i did was replace the positive battery cable with this: https://www.amazon.com/dp/B001DX9VVC?ref=ppx_pop_mob_ap_share

Then the issue started. My mechanic and I have looked over the cable and the install and all its good and its giving good reading. Did something get unprogrammed and causing this? Idk but im at lost.

I have a blackbear tune with volant cold air intake, long tube headers, magnaflow high flow cats, new spark plus and wires, new oem fuel pump with all brand new oem fuel lines from front to back, all new oem evap system with all new lines. Everything has been running good. This just start suddenly.

Mpg are super low, running alittle rough. I did sent a datalog to blackbear in hopes he can see something.

 

[petethepug]

Can the tune safely be turned off / turned on, to shake down things from an unaltered stand point?

If you had a battery lead off the first thing I’d do is reboot or discover how to reload the tune from a blank slate. If your BCM was pissed off about the momentary voltage loss it may have sent it over the edge or corrupted a file.