some background information (2001 xj)

I was having starting issues. Jeep was completely dead, stayed disconnected for about 2-3 days, turned out to be bad terminals.

After that was fixed, i went to start her up, and it just jumped up to 80 psi (ran just fine), turned it off and back on and it sat at 40 psi.

It usually used to idle at around 20 and went up to 40 while the engine was under load (acceleration), but now it seems to be at 40 while idling and 50 under load.

She runs fine (takes a while to shift, but I think i just gotta adjust the cable), any idea what it could be? I'm thinking its the oil pressure sending unit? and can it possibly be related to the battery issue?

thanks in advance

 

If the battery terminals were trashed I going to say find and renew all the ground points before spending any money. If it is the 15 year old sensor at fault OEM is the only viable replacement.

 

I do not know what is at fault, I'm only guessing it's the sensor.

 

^
Disconnect the battery and clean all the grounds first.

 

Everything with grounds and battery has been taken care of already

 

My experience with my '00 is this. Cold runs about 45 to 50 at an idle. Runs at about 22 at a very hot idle and 40 to 45 when driving. About 2 years after I owned the her, been about 3 1/2 now, it jumped up to about 80. Replaced the oil pressure sending unit and all is fine. Everybody will tell you to use a Mopar one. I did not. Bought mine from Napa. The better Echlin line one. Are they right? Time will tell. So far so good.

 

This is why Jeep no longer has oil gauges in its models starting with the WK in 2005. Unless you have an engineering degree in fluid dynamics the gauge is useless and freaks owners out. Bottom line; pressure, any pressure indicates engine is getting lubed.

 

ive also heard to only use the oem mopar sensor, due to a lot of people having issues with aftermarket

nope, only an engineering degree in electrical and computer engineering, maybe i should go back and study fluid dynamics

 

A pegged oil pressure gauge could be a failed sender, but it's probably a wiring issue. The sender provides resistance to current in the circuit, which varies as oil pressure changes. The changes in current then move the needle on the gauge. If the circuit is shorted somehow, there's no resistance, and the full current running to the meter pegs it.

Check the wires going into the connector for the sender for damage to the insulation. If you have had a sender fail in the past and leak oil into the connector, that oil can eat the insulation off the wires and allow them to short out. If you see bare wire, that's probably your problem. If the wires are in good shape, it may be the sender itself (although those usually fail low rather than high). If you see any sign the sender is leaking, replace it anyway. You want to spend the extra money on a real Mopar sender from the dealership, because the parts store senders are notorious for being junk.

You can also try wiggling the wires while someone watches the gauge. When mine was pegged, touching the wires while the Jeep was running actually made it quit, which was a bit of a surprise since I wasn't expecting it. I had to cut a few inches up into the wire loom to get to some good wire to splice in a new connector.

 

Sorry I wasn't picking on you....just making a valid point. Replace your sending unit.

 

I had a MOPAR one from the dealership and it didn't even last 6 months.

When I had other units die (after several years of use), they just read lower and lower until they would be 0 at idle. When the MOPAR one died, it just froze in the middle of the gauge and never moved again, even with the engine off.