Open request to help interpret TunerPro recorded log

[Moss]

Hello,

1995 Chevy K2500 5.7 350 TBI with 4l60e trans. 131k miles.

I recorded a data log today on tuner pro on a loop from the house, and four short stretches going 55, 60, 65, and 70mph. I'm asking anyone who is willing if they'd be able to take a look and see if anything is out of normal parameters. Any information is very valuable as we've been kind of stumped.

Issues include:
-Oil consumption (1qt/~600mi)
-Black soot on tailpipe
-Very rich smelling exhaust
-Exhaust (visually) not steady but releasing in plumes
-Intermittently shaky idle.

Tested catalytic converter today and the outlet is hotter than the inlet.
We have replaced the pcv valve, coolant temp sensor and sender, thermostat, distributor cap, spark plugs & wires x8, MAP, EGR valve, and fixed a cracked vacuum hose on the charcoal canister.

Willing to try answering any questions and appreciate anyone able to help out.

Moss

 

[L31MaxExpress]

If I get some spare time, I will look at it.

 

[Scooterwrench]

A quart of oil in 600 miles is a significant amount. Is it leaking or burning it?

 

[Moss]

A quart of oil in 600 miles is a significant amount. Is it leaking or burning it?

It is, and it was worse when I first got the truck a few months ago.

I believe it is burning it as there are no drops under the vehicle and under the motor only has a very thin wet layer.

Using STP conventional 5w-30.

 

[Scooterwrench]

That could be some of the black you're seeing at your tailpipe. What do the plugs look like?

 

[Orpedcrow]

Do a compression check while the plugs are out too.

 

[Scooterwrench]

Is the STP an attempt to reduce oil consumption or do you have low oil pressure too?

 

[Moss]

That could be some of the black you're seeing at your tailpipe. What do the plugs look like?

The plugs didn't look super offensive when we removed them, some white ash type substance, and one had a flake of something on the porcelain. I thought I took a picture but I guess I didn't unfortunately.
I can pull some tomorrow and see how the new ones are looking and add a picture.

Do a compression check while the plugs are out too.

We'd like to. I have been meaning to do that for a while, but I don't have a compression tester. It's a work in progress.

Is the STP an attempt to reduce oil consumption or do you have low oil pressure too?

The STP is just the brand of oil I used. The oil pressure is not low, it's actually abnormally high if the oil pressure sensor is accurate:
-Hot idle: 45ish psi
-In-gear (stopped): 57-65psi. Wavers with the idle.
-In-gear (in town, 30mph avg): 60-65psi

 

[L31MaxExpress]

Not impossible to be that high, but unlikely especially with 5w30. My fresh thrown together spare parts L31 with new bearings and great clearences using split sized bearing shells in some journals (STD and the random 0.001 oversize bearing halves, where needed to reduce the clearence) is 50 psi at hot idle but that is with 15w40 Rotella in it and a M99HVS.

 

[Moss]

Not impossible to be that high, but unlikely especially with 5w30. My fresh thrown together spare parts L31 with new bearings and great clearences using split sized bearing shells in some journals (STD and the random 0.001 oversize bearing halves, where needed to reduce the clearence) is 50 psi at hot idle but that is with 15w40 Rotella in it and a M99HVS.

Would it have anything to do with the head gasket job the previous owner had done 1-2 years ago? Valve guide seals were replaced as well.