3rd oil change, noticed something different....

OVERKILL

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It doesn’t have a “sensor”.
It has a pressure switch, and the ECU makes a calculation based on oil temperature and RPM…

It uses a pressure switch that only trips on when the pressure falls below something in the 4-7 psi range.

I’ve seen several that we’re making 7-9 psi on a manual gauge at hot (219-221) idle.
It definitely has a sensor, which is how the oil pressure figures in the cluster are derived. This isn't a 1990 Ford where the gauge just sits at the same spot all the time. At the same RPM and same oil temperature different oils yield different pressures, because the device is an actual oil pressure sensor.
A3AD1590-A9A7-4BCE-897A-864A8337AEB6_1_105_c.jpeg



Where are you checking oil pressure? The location on the top of the timing cover is for the VCT system, this is separate from the sensor and location used for system pressure.

But the system does make a calculation, it infers viscosity from oil pressure and oil temperature and this is how you end up with the "wrong viscosity" code if you deviate too significantly. It knows that an xW-20, within reason, should produce a certain amount of oil pressure at a certain RPM and temperature. If that pressure figure is out of whack, it assumes you've used the wrong oil and throws a code.

Edit:
Chrysler sells it as an oil pressure sensor (not switch) under part # 68334877
Screen Shot 2022-08-15 at 11.25.00 AM.jpg


This goes on the filter adapter (it's #3 in this diagram) in engines without the factory oil cooler:
1660577221659.jpg
 
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It definitely has a sensor, which is how the oil pressure figures in the cluster are derived. This isn't a 1990 Ford where the gauge just sits at the same spot all the time. At the same RPM and same oil temperature different oils yield different pressures, because the device is an actual oil pressure sensor.
View attachment 112629


Where are you checking oil pressure? The location on the top of the timing cover is for the VCT system, this is separate from the sensor and location used for system pressure.

But the system does make a calculation, it infers viscosity from oil pressure and oil temperature and this is how you end up with the "wrong viscosity" code if you deviate too significantly. It knows that an xW-20, within reason, should produce a certain amount of oil pressure at a certain RPM and temperature. If that pressure figure is out of whack, it assumes you've used the wrong oil and throws a code.
Most of them had single wire switches attached on the front end of the oil filter… they were like this for years and years, and yet they displayed a pressure…

Single wire switches do NOT measure pressure…
 

OVERKILL

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Most of them had single wire switches attached on the front end of the oil filter… they were like this for years and years, and yet they displayed a pressure…

Single wire switches do NOT measure pressure…
Single wire units are typically switches, but Ford sold both. Not sure if you are familiar with much marine stuff, but most of those oil pressure sensors are single wire too.

Back with the EEC-IV era Ford vehicles you had both switches and sensors, depending on the vehicle. Most of the vehicles had the switches, but the Mustangs had the sensor. Was easy to tell as the switch was tiny while the sensor was larger and shaped like a bell.

This was the sensor/sender:
1660581609893.png


This was the switch:
1660581635240.png


In some instances the cluster was the same, so you could swap-out the switch for the sender if you wanted real oil pressure readings.

All that to say that just being a single wire doesn't necessarily mean it's just a switch ;)
 
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Single wire units are typically switches, but Ford sold both. Not sure if you are familiar with much marine stuff, but most of those oil pressure sensors are single wire too.

Back with the EEC-IV era Ford vehicles you had both switches and sensors, depending on the vehicle. Most of the vehicles had the switches, but the Mustangs had the sensor. Was easy to tell as the switch was tiny while the sensor was larger and shaped like a bell.

This was the sensor/sender:
View attachment 112652

This was the switch:
View attachment 112653

In some instances the cluster was the same, so you could swap-out the switch for the sender if you wanted real oil pressure readings.

All that to say that just being a single wire doesn't necessarily mean it's just a switch ;)
 
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Single wire units are typically switches, but Ford sold both. Not sure if you are familiar with much marine stuff, but most of those oil pressure sensors are single wire too.

Back with the EEC-IV era Ford vehicles you had both switches and sensors, depending on the vehicle. Most of the vehicles had the switches, but the Mustangs had the sensor. Was easy to tell as the switch was tiny while the sensor was larger and shaped like a bell.

This was the sensor/sender:
View attachment 112652

This was the switch:
View attachment 112653

In some instances the cluster was the same, so you could swap-out the switch for the sender if you wanted real oil pressure readings.

All that to say that just being a single wire doesn't necessarily mean it's just a switch ;)

These had gauges… the switch didn’t measure anything…
 

ZeeOSix

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It doesn’t have a “sensor”.
It has a pressure switch, and the ECU makes a calculation based on oil temperature and RPM…

It uses a pressure switch that only trips on when the pressure falls below something in the 4-7 psi range.
What's suppose to happen when the switch trips at low oil pressure? A Big warning light come on indicating low oil pressure?

I’ve seen several that we’re making 7-9 psi on a manual gauge at hot (219-221) idle.
Did you swap oil filters in that test to see if a different filter changed the pressure reading at idle? If the manual oil pressure gauge was located after the oil filter then it should read the same regardless of what oil filter is installed. Unless the oil pump is shot.
 
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I ran Motorcraft 5w30 semi syn in my 2.7 for roughly 60,000 miles, maybe more. Nice and quiet. On a whim, I went with SuperTech full synthetic for a couple of changes. Nice and quiet. The last time I was staring at the oil selection at Walmart, I bought a couple of changes of the Pennzoil Platinum, based on reviews here, and tried it. Immediately more valvetrain related noise when driving up the hill in the morning with a cold engine....and yes, I can tell the difference. Not a lot of noise, but more than it had with the other oils. When the engine is warm, no noise. The 2.7 (great engine, now showing 94,000 miles) uses/used no oil with any of the three brands.
I'll shorten my change interval until I use the Pennzoil up and I'll go back to the SuperTech.
Filters have always been Motorcraft.
 

OVERKILL

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These had gauges… the switch didn’t measure anything…
OK, but that also shows both styles at that link, with 3 pins and with 1 pin.

Sounds like the "gauge" was like the Ford gauge I described that was effectively a dummy gauge.

2009 was the year VCT was introduced, so that's probably when they eliminated the pressure switch/dummy gauge combo.

If I look-up a 2009 Dodge Charger R/T with the 5.7L, the oil pressure sender is 05149062AB, which is a 3-wire unit:
1660593208480.jpg


This part first appears in 2007.

Think I found the answer though:

If I do a search for a 2011 RAM 1500 with the HEMI, I get two different units, that fit the two different variants that were available:
1. 5149062AA - 3-wire, fits: 41 - SEDAN/QUAD CAB SWB, 6 - Lt. Duty DODGE 4WD, 61 - REG CAB 6.5 FT BOX, 62 - REG CAB 8 FT BOX, 98 - CREW CAB W.B.9, EZE - 8 Cyl 5.7L HEMI HEV, EZH - 8 Cyl 5.7L HEMI MDS VCT

2. 5149097AA - 1-wire, fits: 41 - SEDAN/QUAD CAB SWB, 6 - Lt. Duty DODGE 4WD, 61 - REG CAB 6.5 FT BOX, 62 - REG CAB 8 FT BOX, 98 - CREW CAB W.B.9, EKG, EVE - 8 Cyl 4.7L FFV

The switch doesn't fit the HEMI for 2011, even though it's spec'd for the vehicle, it's only for the 4.7L that didn't have MDS or VCT. So, let's dig a bit further.

If I use the MOPAR part #'s for the single-wire units you found on Rock Auto:
1. 5149097AA - Fits: EK0, EV0, EZA - 8 Cyl 5.7L Hemi Magnum SMPI; EK0, EV0
2. 4868672AA - Fits: EK0, EV0, EZA - 8 Cyl 5.7L Hemi Magnum SMPI; EK0, EV0

You'll note neither of them say MDS or VCT. So it looks like the pressure switch was only spec'd for HEMI's sold without VCT and MDS.
 
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OVERKILL

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What's suppose to happen when the switch trips at low oil pressure? A Big warning light come on indicating low oil pressure?


Did you swap oil filters in that test to see if a different filter changed the pressure reading at idle? If the manual oil pressure gauge was located after the oil filter then it should read the same regardless of what oil filter is installed. Unless the oil pump is shot.
Yeah, the pressure switches usually trip at like 5psi or something to tell you something is wrong.
 

ZeeOSix

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OK, but that also shows both styles at that link, with 3 pins and with 1 pin.
Like you showed earier, it's possible to make a pressure sensor with one wire. Depending on the sensor design, it could be 1, 2 or 3 wires.
 
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I don’t know about dodge but I know there are plenty of vehicles where the oil pressure is computer calculated, aka completely fake, using only a 0/1 pressure switch. The oil pressure PID that can be read by a scanner, as well as the oil pressure gauge, were estimated values, based on temp and rpm. Owned one such a vehicle, 2002 GMC envoy 4.2.

So just because you are seeing an oil pressure doesn’t mean that’s the actual oil pressure, just that you have oil pressure. If the switch fails or you truly have no oil pressure the switch would tell the computer which would then just say 0.
 

OVERKILL

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I don’t know about dodge but I know there are plenty of vehicles where the oil pressure is computer calculated, aka completely fake, using only a 0/1 pressure switch. The oil pressure PID that can be read by a scanner, as well as the oil pressure gauge, were estimated values, based on temp and rpm. Owned one such a vehicle, 2002 GMC envoy 4.2.

So just because you are seeing an oil pressure doesn’t mean that’s the actual oil pressure, just that you have oil pressure. If the switch fails or you truly have no oil pressure the switch would tell the computer which would then just say 0.
My Expedition "faked it" with oil pressure, had a dummy gauge, the ECM really had no idea what oil pressure was, it didn't need to, nothing depended on specific oil pressure for its function.

However, in engines with VCT systems and MDS/AFM, where these components are hydraulically actuated, knowing the oil pressure is important, so they will have real pressure senders. Based on the part # searching I did above, it seems Daimler-Chrysler/FCA went full-bore on real sensors when the HEMI got MDS and VCT, while the 4.7L continued on with just a switch, same with the 3.7L V6.
 
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