I have a 2002 SL1 1.9L SOHC with 199k miles and has low oil pressure. At running temp its only pulling 25psi at 2500RPM and less than 5psi at idle.

What is the recommended oil pressure? or problem suggestions?

 

Is the oil light on on the dash?
Do you have a full 4.0 quarts in the crankcase? Did you when the oil light came on, if it did?
How much oil does it burn per 3K mi or per tankful of gas?
How often do you change the oil and what are you using (5W30, 10W30, etc)
How are you reading the pressures? Through the existing sending unit/retrieval of said data via scanner?

Sorry for the interrogation -- just trying to collect the background info up front.

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1) Minimum oil pressure by design is 13psi at idle

2) The setpoint that triggers the switch that triggers the oil light on the dash to light up is 3-7 psi.

3)The dash oil light is indicative of low oil PRESSURE and has NOTHING to do with INDICATION of oil LEVEL. You can have no oil pressure with all 4 quarts in the car. Oil light will come on.
4)If you let your car idle w 5psi oil pressure (truly 5 psi and not a bogus reading), you are doing severe internal damage to the engine. If this were the case, you'd probably hear the damage (probably a knock) and would have mentioned so.

Based on information provided to date, I suspect bad oil pressure sensor/sender IF the oil dash light is NOT coming on at idle AND going away at/by 2500 rpm.

Looking forward to answers to the above questions

 

I am full on oil, and it was not low when the light came on initially. I do regular oil changes at 3000 miles uaing valvoline 10w-30. It will usually go through no more than a quart per oil change. Since then I have disconnected the light to install a manual pressure gauge.

 

So then I assume the pressure readings you quoted were from a manual gauge?

All things considered equal, where the sensor/switch is is located (right at the output of the oil pump (I believe), and where/how you may be measuring it may be causing a discrepancy between what the OEM sensor/switch and your manual pressure measurement are showing. I'm not saying you're doing anything wrong -- just that there may be a reading shift based on the design.

1) Does/did the oil light go off when you reach 2500 rpm? I know you can't have both manual and OEM hooked up at the same time --- my point is this:

If you measure 25psi at 2500 rpm with OEM setup the oil light should be OFF hands down if your manual measurements are correct.

If the oil light is on steady, than either the pressure switch has failed and is giving bogus readings to the PCM, or you are reading artificially HIGH values manually and the OEM sensor is fine and your pressure IS really around 5psi (if the oil light stays on constantly) even at 2500 rpm.

See if you can get a hold of a realtime data scanner and probe the PCM for oil pressure. That'll tell you what the PCM is getting for readings and why it's turning on the light.

If you get gibberish--or even if you don't--- it may also be a simple contact corrosion or wiring problem somewhere between the sending unit and the PCM (can't believe I missed that one for so long). Trace the entire route back to the PCM. Since the sensor is likely on a fuse, you may find that along the way.


If your oil pressure was 5 psi at idle, I really think the engine would be heavily damaged by now.....

 

The manual guage is replacing the pressure switch. But yes the light went off when it was at a high rpm.
It only flickered at low idle. The lifters do clatter significantly after running the car for a period of time. But is fine after letting sit over night, and runs normal without clatter

I have narrowed it down to not a guage issue. The One I'm using was connected to the same port as the light and has been calibrated. I'm leaning towards the area of oil pump issue or clogged sump screen.

 

10 psi per 1000 rpm has been the racer's standard for years. So the 25 at 2500 is acceptable but the 5 at idle is too low. I would drop the pan and take a look at the bearings. Check both rods and mains. If you see copper it is time for a rebuild. That is assuming the bearings are copper backed. If you can catch your finger nail on the grooves in the crank it's time for a regrind and undersized bearings.