driving home from lunch today, i was stopped at a red light and my jeep started idling at about 2-300 Rpms, the oil pressure dropped to 0, the check gauges like came on, and when i tried to gas it, it sputtered, no change in rpms and then it died. Stared it back up and it went. This happened 3 time until i made it home. im now scared something is really wrong. i changed my oil pressure sensor less than a year ago. Could it be a clogged fuel injector causing the no change in rpms? Its a 97 4.0 280k in the clock (last oil change was 2800 miles ago; changed every 3k with penzoil high mileage)

 

an injector wouldn't cause that.. Maybe CPS? are you sure just the oil pressure dropped to zero or did all the gauges? It's a common problem on the 97+ for gauge cluster to die and come back.

 

yes it was just the oil pressure gauge

 

I suspect the gauge and warning light are doing exactly what they should. At 2-300 RPM the pump just isn't turning fast enough to create enough pressure. I think you can rule out a clogged injector too. It would idle just fine, but lack power when driving. Maybe idle air control.

 

Ever cleaned your throttle body?

Last tune up with plugs, wires, cap and rotor?

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 retracted, the air control passage flows more air which raises the idle speed. When the valve plunger is extended, 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. This should be part of a normal tune-up procedure and whenever idle/stalling issues are present.

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). On 91 and later, it may be easier to just remove the whole throttle body. Be sure to use a new throttle body to manifold gasket when reinstalling.

“Gently” wiggle out the IAC from the throttle body. Gasket/O-ring 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 oxygen sensors. 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 bore itself, the butterfly valve inside of the throttle body and it’s edges, and all associated linkage as long as you have things disassembled

Revised 10-6-2014

 

BINGO You have other issues, oil pressure should not even be used as the topic.

 

And so ?? It got your's and 100 others to look at it, some good answers, and a mod could change it if needed.

JMHO, your results may, and will vary.

 

Thanks for all the replies. My last change of wires, cap, and rotor was actually just in November.. And sorry for the oil pump title. thought since there was no oil pressure, it might be a bad pump.

 

And the throttle body and IAC cleaning?

 

haven't done. don't have school tomorrow so i will do it then.