2.5L Intermittent Power Loss - JeepForum.com
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post #1 of 4 Old 03-25-2014, 03:21 PM Thread Starter
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1993 YJ Wrangler 
Join Date: Mar 2014
Location: Glenmoore
Posts: 1
2.5L Intermittent Power Loss

Hi, new to the forum, this is my first post. I was hoping to bend some experienced ears on the trouble I've been having with my 4 banger jeep ('93 YJ2.5L)

-My engine will occasionally sputter like it is running rich and I lose power, then it clears up

-My temp gauge or temp sending unit does not work, 90% of the time the gauge needle sits all the way on cold. Every once in a blue moon it will decide to work for a bit, but no correlation to frequency of the sputtering/power loss

-Heat works, coolant level is fine

-Throwing O2 sensor codes: 21 (O2 Sensor/circuit) and 52 (O2 Sensor: Rich condition)

-Sputtering happens both when engine is cold and fully warm (closed and open loop ECU conditions)

-I replaced the fuel filter, didn't clear it up. Fuel pump was replaced only a year ago but unsure of the quality of part used (previous owner)

-Also, possibly related, but maybe not, I think I am burning oil. The oil level keeps dropping and I don't think its leaking. Smells like buring oil when I park. Possibly oil fouling plugs intermittently? Haven't pulled the plugs yet but I have a fresh set I can put in

Could a bad O2 sensor cause the sputtering like that? I thought after it warmed all the way up the O2 sensor would have no effect.. then again if my temp sender is no good my ECU might not know its warm and never go to closed loop.

Could my bad water temp sensor/sending unit or a bad thermostat trick my computer and make it dump a bunch of fuel every once and a while to bog me down like that?

Also I've heard YJ's have a common problem with the crank position sensor.

Stupid sensors! Making my jeep run cruddy! So insensitive.

I appreciate any help/advice/conjectures/wild hypotheses -CHEERS!!

CafeCowboy is offline  
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post #2 of 4 Old 03-29-2014, 09:45 AM
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1995 YJ Wrangler 
Join Date: Mar 2014
Location: logansport
Posts: 16
Runnign out of power

I am having similar problems with running out of power at the top of shift range. Only happens sometimes, but can't give it full throttle sometimes. I f I back off then step on it again it seems to be ok, but only for a while. how can I tell if it is fuel pump... or o2 sensor... or plugs.. or wires..?
happyhollowhors is offline  
post #3 of 4 Old 03-30-2014, 01:06 PM
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1991 YJ Wrangler 
Join Date: Aug 2012
Posts: 4
I had a similar problem with my '91 4.0. Tried replacing o2 sensor, fuel filter, etc. It also smelled bad. It was a bad catalytic converter. Once I replaced that, runs like new.
slamb is offline  
post #4 of 4 Old 03-31-2014, 08:46 AM
Web Wheeler
1989 YJ Wrangler 
Join Date: Apr 2008
Location: Detroit
Posts: 24,647
No conjecture or guessing. The O2 is definitely a problem and will dump fuel. Deal with it first. Check the O2 sensor and sinse it says you are running rich I would start with checking your fuel pressure. It is easy to do. Rent the guage frm the parts store. 31 psi idle, disconnect the vacuum line to the pressure regulator 39 psi, connect it and turn the key off and it should stay above 20 psi for 20 minutes.
Que89YJ is offline  

cps , ecu , o2 , sensor , YJ

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