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Unread 02-12-2009, 10:04 AM   #1
firedoghfd
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Rough idle, loss of power on acceleration…..but only sometimes.

I have a 1999 Jeep Cherokee Inline 6 and started to have some issues a few weeks back. The jeeps will sometimes idle rough, not really rough but enough to notice something is off. Also at different speeds (sometime in the 30-40’s other times 50-80) it will run rough when trying to accelerate which feels like a loss of power. You can still accelerate just not as smooth as before. The jeep has about 125,000 miles on it. New spark plugs where put in at about 115,000.

I have also noticed a small oil leak right around the oil filter. Sometimes there is a few drops of oil on the filter and a small stain in the drive way. However all fluid levels are ok, in fact just about at the top.

What are the most likely items that should be looked at? Unless this sounds 100% like the fuel filter the last thing I want to do is drop my tank.


I’m also new to car repair. I can figure most things out just don’t know all the terms.
Last summer I had to rebuilt most of coolant system (fan clutch, water pump, thermostat, tubes…..) with no issues. It just takes me a little more time then other people.

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Unread 02-12-2009, 10:13 AM   #2
CJ7-Tim
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Finish the tune-up with a new cap, rotor, and new wires. Don't buy cheap parts. Add a can of fuel injector cleaner to the gas tank on the next two fill-ups.

Test and consider replacing the Coolant Temperature Sensor on the thermostat housing. If the sensor is weak or slow it will keep you in cold loop too long and you can have hesitation, rough acceleration, or a power loss as symptoms. A bad CTS may or may not cause a CEL light on the dash.

The fuel filter is not routinely serviced.
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Last edited by CJ7-Tim; 02-12-2009 at 10:55 AM..
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Unread 02-12-2009, 10:36 AM   #3
firedoghfd
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the loss of power, hesitation, rough idle happens when the engine is cold and it happens if i've been driving for a hour or more.

I put in bottle of cleaner and have about 1/4 of a tank left, i'll add the 2nd.

i'll replace the wires, cap and rotor today and let you know
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Unread 02-12-2009, 10:52 AM   #4
CJ7-Tim
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Originally Posted by CJ7-Tim View Post
..... Test and consider replacing the Coolant Temperature Sensor on the thermostat housing. ....you can have hesitation, rough acceleration, or a power loss as symptoms.
Test the TPS also.
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Unread 02-12-2009, 04:19 PM   #5
MxAjN
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your small oil leak may be your oil filter adapter o ring or gasket, happened to me about a week ago costed like 40 bucks at my mechanic, but the parts only like 6 dollars, just a p.i.t.a
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Unread 02-13-2009, 05:38 AM   #6
tjwalker
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Quote:
Originally Posted by CJ7-Tim View Post
Finish the tune-up with a new cap, rotor, and new wires. Don't buy cheap parts
Gotta start with cap, rotor and wires as Tim says. Don't want to be chasing your tail and your have to eliminate tuneup stuff first.
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Unread 02-13-2009, 07:00 AM   #7
scoon
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Hey there,

Also check your grounds and battery terminals.
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Unread 12-02-2013, 04:38 PM   #8
tapied
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had this same issue on 00 Jeep Cherokee inline 6

I had this same issue for almost a year. Had had coil pack changed (no wires on 00 Cherokee, model just coil pack directly on plugs), spark plugs, tune up, carbon build up treatment recommended by Jeep official repair bulletin, not to mention mechanics looking at it repeatedly and scratching their heads.

FINALLY, got a mechanic with lots of experience (30+ years) who told me it was my aftermarket Bosch spark plugs....rolled my eyes and didn't believe it at first...then he bet me "no cost for new plugs and labor if it didn't fix the problem" so I told him to go ahead feeling skeptical. I had put the Bosch plugs in because they were "nice" and expensive and supposedly improved performance....he said he had seen the same problem about 20 times and the same fix fixed all of them.

He replaced the spark plugs with standard OEM plugs. No aftermarket fancy stuff....worked like a dream!!! Had no problems for the next 2 years until I totaled it Best and simplest fix I've ever had. In fact, did the same thing for a friend who was having the same problem...again, worked like a dream, no problems since for him.

Hope this helps
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Unread 12-05-2013, 11:49 PM   #9
desertratXj
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im having the same issue as well did the tune up replaced the tps but forgot to flash the pcm i also replaced my catylitic converter and muffler which somewhat helped the next thing i have to replace will be the o2 sensors everyone ive talked to has said if replacement of your cat doesnt work it could be the o2 sensors
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