4.0L Woes...Bogging down on acceleration?? - JeepForum.com
 
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post #1 of 13 Old 06-27-2010, 03:20 PM Thread Starter
Hella
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4.0L Woes...Bogging down on acceleration??

Okay so the last week has been hella with this 4.0L. It started with a misfire on a few cylinders and I finally fixed that today. So I took it for a ride and now the engine bogs down bad on acceleration. Gas mileage has seem to be crappy also. Also hear a rattle coming from underneath the jeep, almost sounds like a trans problem but maybe cat? Also after I stop driving I hear a ticking coming from underneath the valve cover. Just curious if anyone can help me out and point me in the right direction. Thanks in advance


04 TJ "Leyla" Rubi..
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post #2 of 13 Old 06-27-2010, 03:32 PM
GOLENJEEPTJ
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How did you fix the cylinder misfires?Did you replace the plugs?If so,which ones exactly?Could need the throttle body cleaned.Were you getting any codes?Please elaborate a bit more on how this whole thing started.
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post #3 of 13 Old 06-27-2010, 03:54 PM Thread Starter
Hella
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The whole situation started driving down the freeway and I got a misfire. Which is right after I got some cheap gas. I talked to my uncle who is a mechanic and he said to try to replace the cam sensor. Well I replaced the cam and crank sensor today and got fresh gas and took it for a ride. I got on the freeway and drove it and it only missed once. The code didnt store in the computer so I couldnt see what cylinder. Was coming back down the freeway and it seemed like it was bogging bad and I was dumping gas bad also. Got off the freeway and now when I accelerate it bogs bad. It dropped a quarter of a tank driving about 25 miles and no check engine light. In park or neutral the engine will rev out but it def seems sluggish and takes a while to get through the RPMs. Getting confused more everyday.

It was cylinder 4,5 and 6 when it was misfiring the first day...Pulled the plugs that night and they looked fine so I didnt replace them. It was only misfiring while I was on the freeway...

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post #4 of 13 Old 06-27-2010, 04:12 PM
mkleza
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sounds like it could be the cat. Get under the jeep after the exhaust has cooled down and give the cat a pretty good hit, if it rattles then it is shot.
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post #5 of 13 Old 06-27-2010, 06:45 PM Thread Starter
Hella
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not the cat we figued out...still bogs on acceleration.

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post #6 of 13 Old 06-28-2010, 03:36 AM Thread Starter
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bump for help, please!

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post #7 of 13 Old 06-28-2010, 04:09 AM
cosmo05
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Mine did the same thing, it was the O2 sensor, the one in the front on the exhaust header.
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post #8 of 13 Old 06-28-2010, 09:54 AM Thread Starter
Hella
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was your check engine light on?? Just curious. If not then it looks like im going to be throwing o2 sensors at it...

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post #9 of 13 Old 06-28-2010, 10:32 AM
cosmo05
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Yes, it would come on, then go out for awhile and then come back on. I did check it with a hand held computer diagnostic but it not indicate an O2 sensor for some reason. Run a diagnostic on it anyway and see what it comes up with. The other thing I would get in addition to what your described was occasional pops out the throttle body.
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post #10 of 13 Old 06-28-2010, 10:36 AM
mdm
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Cat doesn't have to rattle to be bad.

Keep in mind that free advice can frequently be worth less than you pay for it.
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post #11 of 13 Old 06-28-2010, 11:25 AM
Unlimitedlou
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I was running in to the same problem and I finally figured it out. Your oil pump drive assy and mine are different, but just by a little bit. The rattling you are hearing may be due to the shaft moving in the top bushing of the oil pump drive assy. I experienced all the same problems as you, with no CELs. Eventually it gets worse. Put your hand on it while it is running and you can feel it. Just trying to point you in another direction.

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post #12 of 13 Old 07-02-2010, 07:39 PM
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Bump
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post #13 of 13 Old 07-02-2010, 11:08 PM
aspjeepguy
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Mine did what you are describing. It started to misfire on the middle two cylinders. Then it would run but as soon as you got up to highway speed the jeep would seem to miss bad. What I found out was that the screen in the gas tank was plugged.

The jeep ran like a top after I did that and that was 30k ago
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