Could a weak battery cause oil pressure indication issues?

Yes, the Tech-2 can see oil pressure. It also runs an algorithm to test the sensor, it knows where the pressure should be and compares that to what it sees. If the numbers aren't copacetic, a code will set. An OBDII Adapter with a phone App can see oil pressure too. I think it's time for a new oil pump. Could also be cam bearings but would first rule out the easy stuff. If the bearings are suspect, an oil analysis can help show if and where it's happening.

Thanks for your service as a dirty contractor Joe. My buddy was wounded in Iraq with the USMC and spent several years in Afghanistan as a contractor running those aerostats with the cameras on them. Take some of that contractor bounty and treat yourself to a 6.2 L9H!

The fact that oil pressure returns after a shut down would indicate a build up of particles at the oil pump pick up tube screen or the oil sender screen. Since both of these are a screen and not a true particle trapping filter, the particles clogging the screen are able to flow away from the screen when oil flow stops and then take a while to build up again when restarted.

JEFFC said:

The fact that oil pressure returns after a shut down would indicate a build up of particles at the oil pump pick up tube screen or the oil sender screen. Since both of these are a screen and not a true particle trapping filter, the particles clogging the screen are able to flow away from the screen when oil flow stops and then take a while to build up again when restarted.

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Good call on this. Especially if recent or former work was done on the engine and someone used too much sealer on certain gaskets.

JEFFC - Thanks for the input. I was kind of thinking the same-ish. I replaced the screen below the sender about a year and a half ago. I think this is worth exploring, but I am working to rule out a gauge issue first. I have a mechanical test kit, but I need an adapter. I have been waiting several days for it and just got an email from Amazon today saying that its lost and they are refunding me. I have reordered, and will report back once I am able to check the pressure manually. I will also change the screen below the sender when I take it out for this test. If it were particles clogging the pickup tube, I guess the only way to tell / fix it would be to drop the pan?

swathdiver said:

Yes, the Tech-2 can see oil pressure. It also runs an algorithm to test the sensor, it knows where the pressure should be and compares that to what it sees. If the numbers aren't copacetic, a code will set. An OBDII Adapter with a phone App can see oil pressure too. I think it's time for a new oil pump. Could also be cam bearings but would first rule out the easy stuff. If the bearings are suspect, an oil analysis can help show if and where it's happening.

Thanks for your service as a dirty contractor Joe. My buddy was wounded in Iraq with the USMC and spent several years in Afghanistan as a contractor running those aerostats with the cameras on them. Take some of that contractor bounty and treat yourself to a 6.2 L9H!

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i can see oil pressure on obdII adapter? Ill have to look harder at Torque PIDs...

TheAutumnWind said:

i can see oil pressure on obdII adapter? Ill have to look harder at Torque PIDs...

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Yes, you should be able since I can. @kbuskill

swathdiver said:

Yes, you should be able since I can. @kbuskill

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Yes you can see oil pressure and temperature by using the correct PIDs with the Torque Pro app.

Alright, first, let me say that I really appreciate everyone's help thus far. Today I FINALLY got the adapter to go between the oil pressure sending unit hole in the engine, and the mechanical test gauge that I bought. I got the sender out, and decided to pull the screen below it to check it. There was some crud on it, but nowhere near what I would consider to be "obstructed."
I poked a hole in it getting it out, but fortunately I had one on hand so I put in a brand new one. I got the mechanical gauge all installed (what a PITA), and started the Tahoe.

*In case anyone ever references this thread, I found out that the oil pressure sending unit must be installed in its wiring harness for the vehicle to start, so I left it dangling from the harness while I drove the vehicle*

The good news is that I DID NOT experience the gradual pressure drop off that I have been seeing. I recorded the following data points:

RPM PSI Condition

500 22 Idle
3000 40 Accelerating
3000 40 Cruising
2000 35
500 21-22 Idle
3000 40-42 Accelerating
2100 36-37
3000 42
4000 50 Cruising
500 22 Idle
3000 40 Accelerating
3500 46
4000 48
1100 29

These don't seem terribly unreasonable to me, but I am interested to know what anyone else thinks? I still have the mechanical gauge hooked up and I am planning to do another run, top verify that the pressure remains steady. Is there any other data point I should capture that I have missed here?

Joe

It looks very steady except that the idle pressure is lower than my 02 by 15 psi and lower than my high pressure during accel but others here have said that lower pressure is normal. The filter may have been the whole problem and since mine does not have one I always forget about that. As I said in an earlier post to this thread, I like a mechanical gauge reading for true information. I would go ahead and install a new sender while the old one is off and hopefully the problem is solved.

These don't seem terribly unreasonable to me, but I am interested to know what anyone else thinks?

Joe

Looks totally normal to me