High oil pressure in 2.5L TJ jeep

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Jan 31, 2010
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My jeep started running rough and stumbling at start up recently. It would also miss and run rough until warmed up. The check engine light came on. I figured it's been a while since it's been tuned up so I didn't think anything of it and ran it for a week until I had time to work on it. It's my daily driver to and from work.

When the check engine light would come on, I'd lose my voltage gauge. I confirmed it was a bad alternator so I replaced it. In the process of changing the alternator, I found the oil pressure sensor hanging. It was broken off. I ordered a new one off Amazon. When I got it, I installed it and fired up the jeep. I have full voltage now so that is fixed.


But now the oil gauge pegs, It's still running like crap and I'm concerned why the oil pressure still reads high. I replaced that sensor, thinking it might be defective, and it's still reading high.

I know I'm telling on myself, but I haven't been very diligent with my oil changes as much as I should be. I've ran it up to 8k miles on ocassion. I run 10-30 Dino in it. A few oil changes ago, I ran synthetic blend. I use Fram ultra filters. Last oil change was done at a 15 minute lube shop with valvoline 10-30 and valvoline filter because I didn't have time to change it myself.

I know I need to get a mechanical gauge on there to verify pressure. But assuming its high, what do you think it could be? I've been told it might be a stuck oil pressure relief valve, but I have no idea where its located on this engine. Any help is appreciated.

Thanks
 

monster1

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Its not just magically going to go high, these old Jeep motors barely carry 40psi when hot. Unless you rebuilt it and had very tight clearances and a HV oil pump, its the gauge or sending unit thats at fault. Oil pressure didn't change
Even if I have plugged oil passages or pressure relief valve?
 
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The oil pressure sensors are notorious on these things for going bad. I bought a Mopar sensor from the dealer and every once in a while mine still pegs 80 PSI randomly, swings wildly back and forth for a few seconds, then proceeds to work normally for a long time.
 
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Buy an oil pressure sensor from the dealer. Buying non-factory sensors is always a crap shoot.
I was going to say this.
You will NOT get a working aftermarket oil pressure sensor for that engine. I just use OEM junkyard sensors when I have a problem and it works. But the aftermarket ones do not work.
 
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I put a mechanical gauge in mine. It reads similarly to the factory gauge, though a bit lower. The mechanical gauge is the best way to go. I got a copper T from the hardware store to install both the sensor and the mechanical gauge.
 
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I don’t trust electric gauges at all until they’ve been verified against a known accurate mechanical gauge.

Put a gauge on there and check before worrying about possible causes of high pressure.
 
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Either the sensor is bad OR the sending unit wire was pinched. (If so, you should show 100psi with the key on and engine off.)
 

monster1

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Either the sensor is bad OR the sending unit wire was pinched. (If so, you should show 100psi with the key on and engine off.)
No. I have no reading with just the key on. As soon as I start up, the gauge pegs. I ordered an oil pressure test kit online and will be verifying the pressure to go from there.
 
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It sounds like you got an oil pressure SWITCH instead of a sensor. On my WJ, in 2001 Jeep changed from an oil pressure sensor which reported actual pressure to the dash gauge to an oil pressure switch which only reported "yay" or "nay" to the cluster. I'm not sure if TJ's are the same, but it's pretty easy to tell the difference in parts. A true oil pressure sensor is much larger than a simple switch.
 

monster1

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I bought an oil pressure gauge kit and verified that upon start up, my pressure is around 50psi. I'm going to order an OEM part, install it and see of that fixes the gauge issue. Thanks for all your suggestions and help.
 

JTK

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I bought an oil pressure gauge kit and verified that upon start up, my pressure is around 50psi. I'm going to order an OEM part, install it and see of that fixes the gauge issue. Thanks for all your suggestions and help.
Sounds normal.

Today's aftermarket sensors are way more sketchy than those of years ago. Chrysler/Jeep vehicles seem to be the worst in this regard. Not that an OEM part is the best, but it has the best chance at working with the vehicle.
 
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It sounds like you got an oil pressure SWITCH instead of a sensor. On my WJ, in 2001 Jeep changed from an oil pressure sensor which reported actual pressure to the dash gauge to an oil pressure switch which only reported "yay" or "nay" to the cluster. I'm not sure if TJ's are the same, but it's pretty easy to tell the difference in parts. A true oil pressure sensor is much larger than a simple switch.
I bet they sold him one for a light instead of a guage.
 

monster1

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High oil pressure won't make it run bad. It has other problems. Does it have a cel?

High oil pressure won't make it run bad. It has other problems. Does it have a cel?
Yes. It has a cel. It hasn't remained on since I replaced the alternator. I haven't been able to get around to using my scan tool to see kf any codes have been stored. I plan on giving it a tune up. It's been a while since I've done so.
 
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Yes. It has a cel. It hasn't remained on since I replaced the alternator. I haven't been able to get around to using my scan tool to see kf any codes have been stored. I plan on giving it a tune up. It's been a while since I've done so.
If you turn the key on-off 3x it should spit the code out where the odometer is. No code reader needed
 

monster1

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If you turn the key on-off 3x it should spit the code out where the odometer is. No code reader needed
No hard codes stored. Veried with my buddy's code reader. I had to replace the battery because it was no longer holding enough charge to start the engine. The engine is running like a top now. Thanks again for everyone's help.
 
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