Coastie05

So,I got in the Jeep this morning and my oil pressure was pegged out at 80. Even when the Jeep is warmed up it stays at 80 and regardless of rpm's. I'm thinking it's the sending unit, but just wanted to clarify. All the threads I've been reading have been low or no oil pressure, none about high oil pressure. It drives just fine and idles perfectly. Any help will be appreciated. Thanks!

Coastie05

I'd be replacing it with an OEM sensor…probably from this website.

http://www.partsgeek.com/gbproducts/...FWUV7Aod13YAcg

cruiser54

Excellent plan. Did you change the oil filter recently?

Coastie05

No I sure haven't. I just replaced all my vacuum line and TPS though. Now my Jeep runs like a champ and the check engine light is off. It's just this high oil pressure now. I replaced the vacuum lines and TPS with OEM replacements off of dodgeparts.com. Oh and I just found the sending unit for $10 cheaper on dodgeparts.com….score! haha

Coastie05

So I just went and started the Jeep and now the pressure is reading about 55. Should I just replace the sensor or wait? Also, it started to hunt a bit at idle and sounded like it was going to die and then it just started to idle fine again.

cruiser54

You are good to go!!

investinwaffles

You could try cleaning it and the oil passage its attatched to with a little pipecleaner or something to see if the passage is blocked.

From what I have read, the mopar pressure sending unit is worth the cost over a generic one though. The 4.0 is apparently picky and the OEM Mopar one has lower failure rates than the cheap ones.

Coastie05

Cool, I just wait awhile then. Yea, all I've read is that these engines need OEM sensors, so that's all I've been replacing them with.

salad

Clean out the connector to the OPSU first. Chances are it's full of crap. The OPSU works by varying its resistance so contaminants and corrosion will mess with the signal.

iowaSSfan

My jeep does the same thing off and on. Did not even consider that it could just be the sensor. I will have to pull it off and clean it first. See if that helps before replacing. Where is the sensor located and does it need some kind of sealant on the threads when reinstalling? Thanks.

cruiser54

Right above the oil filter. Don't take it out necessarily, but unplug it and clean the connectors first. If there's oil in there, replace it.

Coastie05

Thanks for the help y'all. I'll go ahead and clean it. Now let me ask this about a different issue I'm having. I just replaced my TPS with a OEM sensor and that fixed most of my problem, but I'm still having a low idle as if it's going to die. This just started happening yesterday and continued this morning. It drives just fine but when I come to a stop it has a really low idle. Also, when I take it out of park and put it in drive or reverse it boggs downs and feels like it's going to die. Could it be the IAC? Even with the new TPS I had a really hard time getting my Jeep to start upon the initial TPS replacement.

salad

Yep. IAC takes orders from the TPS. Usually they just get really gummed up before they die. You ever clean it before?

cruiser54

Courtesy of TJWalker:
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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Coastie05

Nope I sure haven't, but I'm going to now. Hopefully cleaning it does the trick.