Oil Pressure and Low Oil Pressure Warning

kittyboy said:

What's a healthy oil pressure difference in comparison between oil pump galley psi and the valley oil pressure sensor psi?

I realize there are many variables, pump flow, pressure valve pressure, bearing clearances, engine wear, etc... But for this question, I would like to keep it general assuming a stock CTSV PN: 12612289 oil pump with standard LSA bearing clearances.

Say at 700-800rpm, 2000rpm, 5000rpm?

I plan to install a mechanical gauge at the pump galley, and banjo in a mechanical gauge at the valley oil pressure port location.

Thanks in advance for help!

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I wanted to respond with this follow-up to my own post in the case others have already read it, I have some additional background information to add, and a new question to ask?

What originally prompted me to install a mechanical oil pressure gauge in the first place was to verify the accuracy of my electronic oil pressure sensor readings. I needed to verify the following message I received:

"Oil Pressure Low, Stop Engine" along with a very small, tiny red oil dispenser (oil level) icon.

A week ago I drained my oil, then went to refill it the following day. I have a 1qt capacity remote oil cooler in addition to the 6qt stock oil capacity requirement. Usually, the one quart cooler doesn't drain because it's mounted below the pan level. So I conservatively added 5qts initially and returned the following day to check the level and top it off. Looked good the following day, so I figured "assumed" it was full.

Well... I went out to drive, and apparently after the oil warmed up a bit, the nightmare message intermittently began to chime! Checked the OEM oil pressure and my AutoMeter oil pressure gauges, and logs, nothing below 28psi at idle? At this time I was still "assuming" my oil level was good, but as it turned out I was between 1.5-1qt low.

So my question is:

Why did I get a "low oil pressure" warning DIC and chime simultaneous with the low oil level icon? Is it normal to receive both for low oil level?

In the future I'm going to add oil and check the level warm right after with oil still in the top end.

kittyboy said:

I wanted to respond with this follow-up to my own post in the case others have already read it, I have some additional background information to add, and a new question to ask?

What originally prompted my to install mechanical oil pressure gauges in the first place was to verify the accuracy of my electronic oil pressure sensor readings. I needed to verify the following message I received:

"Oil Pressure Low, Stop Engine" along with a very small, tiny red oil dispenser icon.

I week ago I drained my oil, then went to refill it the following day. I have a 1qt capacity remote oil cooler in addition to the 6qt stock oil capacity requirement. Usually, the one quart cooler doesn't drain because it's mounted below the pan level. So I conservatively added 5qts initially and return the following day to check the level to top it off. Looked good, so I figured "assumed" it was full.

Well... I went out to drive, and apparently after the oil warmed up a bit, the nightmare message intermittently began to chime! Checked the OEM oil pressure, AutoMeter oil pressure gauges, and logs, nothing below 28psi at idle? At this time I was still "assuming" my oil level was good, but as it turned out I was 1qt low.

So my question is:

Why did I get a "low oil pressure" warning DIC and chime simultaneous with the low oil level icon? Is it normal to receive both for low oil level?

In the future I'm going to add oil and check the level warm right after with oil still in the top end.

Click to expand...

Responding to my original post with updated information.

Today I connected the mechanical oil pressure gauge at the valley sensor port via banjo fitting to verify the OEM oil pressure sensor accuracy in comparison. The mechanical gauge reads 28-29psi 190F hot idle and holds steady running fresh 5w30 Amsoil with a new WIX oil filter installed. Both the OEM and Autometer oil pressure sensors (electronic) are spot on in comparison to the mechanical gauge.

I havn't compared the oil pump pressure at the galley port yet.

I don't have the schematics, diagrams or ECM logic, but I thought to also test the oil level/temperature sensor. I was surprised that the oil level sensor is advertised as a combo sensor, measuring both oil temperature and oil level, it this acuarate?

(see attached images and video link)
Hot Idle 29psi

The oil level sensor is in the pan I'm pretty sure. The oil pressure sensor is at the top of the valley cover in the rear - again I am pretty sure!

Is it possible you were getting intermittent low pressure (via the sensor) under acceleration that didn't show up on logs? If you've reviewed all of the logs (either via graph or perhaps a filtered histogram to plot PSI over time), then I would check for intermittent wiring or a fault. But suspecting wiring would be my last option, over a true low pressure situation. Checking just at idle won't count, because it would have to be SEVERAL quarts low. If true, it would be under heavy braking, or hard cornering while at high RPM where the oil might slosh away from the pickup and more volume would be moving around in the engine trying to drain back to the pan.

Being JUST a quart low wouldn't trip the sensor unless you were pulling heavy G's on a track or grippy surface IMHO.

07GTS said:

the level should only be a switch that floats in the oil and once its too low closes and brings up the warning, u could unplug it just to see what warning u get to see if its the same ? but shouldnt be pressure related tho, is there any oil in the pressure sensor plug ? thats a common issue for them as the oil leaks thru and causes connection issues

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I re-read your response, now I understand. You meant oil leaking from the upper sensor seal causing oil to migrate into the electrical connector. Ask me how I know? Just replaced a new sensor with another new sensor. (haha) I installed the first one with proper socket and torque specs, let it idle, checked for leaks, sure enough, upper seal leak! New replacement is good, oil pressure readings are accurate. However, same problem exists at 28psi, chime, chime, chime, chime... Tomorrow I'm going to swap the oil level/temp sensor and see what happens.

Had a thought today, maybe some oil circulation resistance due to blockage common to my remote oil cooler? If the hot oil is not able to migrate back down into the pan quickly enough, it may be triggering the low oil level sensor? But if that was the case, I figure after a few moments at 28psi idle it would fill again and re-set. Funny how it is always 28psi when the warning message chime is triggered, never drops below 28psi and then is steady, (see attached video link). In the morning I'm going to replace the level/temp sensor.Oil pressure test video
Note: I have an Improved Racing Baffle installed.

07GTS said:

its an interesting one, the factory has delays before it brings on warnings and also very low in pressure too, but u dont have the factory sensor hooked up ? also for sensors and oil i always avoid using thread tape, only use thread sealant if u have to, the tape can stop contact of the body to earth if it needs the contact it will cause issues or sometimes the tape if used and sensor removed it can curl up inside the thread and when sensor installed the first sign of pressure pushes the little bit of tape into the sensor and it blocks the hole causing issues also, aside from those and actual oil if its in the plug will disrupt the contact of the pins causing issues, but if they are all good its an odd one

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Update 1/6/23:

After disconnecting the oil level/temp sensor, the same 'low oil pressure' warning condition exists, 'low oil pressure' warning chimes and holds steady at 29psi with the oil level/temp sensor disconnected, small red 'add oil' icon also still appears. So I assume the oil level/temp sensor is operating properly and has no effect in relation with the oil pressure sensor 'low oil pressure' warning. Note: Idle is set to 750rpm with an LS7 cam.

Current trouble shooting performed using fresh Amsoil 5w30 and a new WIX filter installed, oil level slightly overfilled, testing at 190F engine/oil operating temperature. When this issue first began I was running Amsoil 10w40. I felt it would be best to run a lower viscosity oil until I could determine the problem. When the engine was new, and for the first 4000 miles I was running Mobile1 5w30.

Engine has 7000 miles of aggressive driving. I have multiple Blackstone reports, and overkill amounts of inspection data and logs.

Previously I confirmed accurate electronic oil pressure sensor gauge readings using a mechanical oil pressure gauge at multiple rpms in comparison.

Blackstone trending reports reflect no excessive/atypical ppm bearing wear over time between scheduled 2000 mile oil changes. The current average engine compression drop is 18%psi cylinder compression compared to new at 172psi, cylinders within 5%-10% difference. Rebuilt heads at 6000 miles. No unusual tapping, knocking, or other sounds. Performance is excellent. I do note increased amounts of carbon in the oil between oil changes, no blue exhaust, and no excessive oil burning/low oil levels between oil changes. No signs of excessive blow-by, catch can volume is normal.

I'm assuming worn/looser bearing clearances exist at this time. In addition, worn piston rings and cylinders. No excessive cylinder wall discoloration or scoring exists. I recently began adding 0.5:100 parts Amsoil 2 stroke engine oil to the fuel aka 3.5oz per 18gl, (full tank).

I'm now leaning towards believing a failing/weakening oil pump pressure valve combined with worn/looser bearing clearances. The stock pump on an LSX376-B15 is a standard LS1/LS6 #6665, in comparison to the LSA #2289, (see attached). I realize the LSX is a priority main oil block (no squirters), compared to the LSA. However, I believe the LSX would benefit using the LSA pump with approx 30% more pressure/flow in comparison, I think the LSA pump would have been a better option with the OEM -B15 long block.

I believe it's possible the E67 ECU measures and interprets oil pressure rates (drop rates) over time based on a table at differing rpms. The ECM logic is a BLACK box to me, and I have no way of knowing for sure, maybe never!

In my particular situation, I only receive the 'low oil pressure warning 'chime' at 28psi-29psi hot idle, oil pressure never drops below 28psi at any time.

I've observed that if I hold a steady rpm and steady oil pressure on a highway, then lightly lift my foot of the pedal, there is a momentary 2psi oil pressure increase. Example: 43psi, let off gas slightly, pressure increases momentarily to 45psi, then decreases.

Thats all I have for now. Any feedback and/or suggestions are appreciated, particularly oil viscosity suggestions. 'Assuming' both worn bearings 'and' a weakening oil pump valve exists, would it be better to use a lighter or heavier oil? Also, what is the hot idle psi for a stock LSA (with oil squirters)?

At this point I'm going to deactivate the OEM oil pressure sensor and monitor the oil pressure via the Autometer gauge, the chime is driving me crazy now! I'll set the Autometer strobe to red and oil pressure audio alarm relay to 25psi.

For the amount of time and effort involved replacing an oil pump, I would rather just hold off and plan for an entire engine rebuild later down the road. I'll just keep driving and monitoring for now.
Thanks...

07GTS said:

im not a fan of increasing pressure but just increasing flow according to the clearances u have and piston squirters, a thinner oil can work better as its will move thru the bearings faster and also help take heat out of them, depends what parts u have as some lifters like a thinner oil too, i was going to use a 10-40 or 5-30 in my build once finished either should be fine if u have ore clearances and the flow of the pump can keep up, but if ur not going below 28psi its odd ur getting a warning, there are oil pressure warning settings in hpt in the engine diag tab not sure if they work but they are there could be worth a adjust to see if it does anything

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Just for clarification, I do not have squirters. But I'm with you on the thinner oil for the same reasons you wrote, pressure as well. That's why I went with 5w30 until I could get my head around this puzzle situation.

I haven't measured the pump galley pressure yet. But based on the current valley pressure there is adequate oil pumping throughout the system. I assume at higher performance levels with increased temperatures the pressure would likely drop further running the 5w30.

10w40 has proven to be better on bearings running higher performance with a boosted engine based on my own oil analysis trends.

All I can 'assume' at this time for whatever reason, or reasons unknown, I now have lower pressure 'and' flow to live with. I'll keep it monitored, at least I have flashing red lights and an audio alarm to help.

Never logged high oil or engine temperatures during all of this. Totally sucks after cooking main bearings on my LSA engine out tracking.

This situation could very well be just the pump, but like I wrote, it's too much a hassle doing just a pump swap only, might as well pull the whole engine and re-build at some point. Especially since I've been running it hard for a while now.

Guess there is no such thing as a forever bullet proof engine in this life for me, engines hate me!

PS: I did compare oil diag settings to stock thinking the same thing, I'll double check. I was in fact making other diag changes approximately about the same time all of this began to occur.

kittyboy said:

Just for clarification, I do not have squirters. But I'm with you on the thinner oil for the same reasons you wrote, pressure as well. That's why I went with 5w30 until I could get my head around this puzzle situation.

I haven't measured the pump galley pressure yet. But based on the current valley pressure there is adequate oil pumping throughout the system. I assume at higher performance levels with increased temperatures the pressure would likely drop further running the 5w30.

10w40 has proven to be better on bearings running higher performance with a boosted engine based on my own oil analysis trends.

All I can 'assume' at this time for whatever reason, or reasons unknown, I now have lower pressure 'and' flow to live with. I'll keep it monitored, at least I have flashing red lights and an audio alarm to help.

Never logged high oil or engine temperatures during all of this. Totally sucks after coking main bearings on my LSA out tracking.

This situation could very well be just the pump, but like I wrote, it's too much a hassle doing just a pump swap only, might as well pull the whole engine and re-build at some point. Especially since I've been running it hard for a while now.

Guess there is no such thing as a forever bullet proof engine in this life for me, engines hate me!

PS: I did compare oil diag settings to stock thinking the same thing, I'll double check. I was in fact making other diag changes approximately about the same time all of this began to occur.

Click to expand...

Update:
After further test driving and an expanded review of past data logs, I have determined that the "low oil pressure" message/chime only activates if oil pressure is at/or below 28psi. So it's probably a combination of normal bearing and pump wear. In the past year oil pressures never dropped below 29psi-30psi at hot idle running 10w30 and/or 10w40.

I do not have any LSA data for 'normal' hot idle oil pressure running stock pump? If anyone can provide this information it would be greatly appreciated. The stock B15 pump is lower flow and pressure compared to the stock LSA pump.

So I am now leaning towards concluding I have no oil system issues after all. The 'low oil pressure' warning may just be a 'hard' code warning that triggers at 28psi oil pressure on a CTSV? Nothing wrong with 28psi oil pressure at hot idle anyway. Cadillac may have set a 28psi minimum because of the squirters?