Author Topic: Clogged Cat?? Anyone had one?  (Read 3411 times)

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jwrape

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Clogged Cat?? Anyone had one?
« on: December 10, 2005, 07:38:36 AM »
My Heep just started acting strange since getting back from Tellico.
Up around 2800 RPMs it seems to bog down and slow the motors rpms. It still goes up to 5k rpms but it seems to be working harder to do it.
I am wondering if anyone has had a clogged Cat on a YJ before? Is it common or should I look somewhere else.
The only other thing I can think of is the fuel filter.

It has always seemed to run better after about 10 minuites of driving. Seems like once the Cat warms up it flows better. Just my thoughts, but I am open to suggestion.
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Offline Jeffy

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Clogged Cat?? Anyone had one?
« Reply #1 on: December 10, 2005, 11:08:23 AM »
Honestly it could be anything.  Mileage would help.  Have you tried recovering  any error codes?

It doesn't make sense for the cat to work up to get better flow.  Unless you melted or broke the cat, it idn't going to restrict flow when starting up.  If you broke it then it should make noise.  If it melted you have bigger problems.   Since you just got back from Tellico, have you checked the exhaust for restrictions?  Crimped tailpipe is a common one.
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jwrape

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Clogged Cat?? Anyone had one?
« Reply #2 on: December 10, 2005, 12:16:20 PM »
171k

Hmm.. The tailpipe did get zip locked on the end but I opened it back up and now it's more like an oval than a circle but I wouldn't think that little different would make that much difference.

Offline Jeffy

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Clogged Cat?? Anyone had one?
« Reply #3 on: December 11, 2005, 12:08:48 AM »
Well, you'll have to check the exhaust and all the sensors.  I still recommend recovering the error codes stored in the computer.
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TexMontana

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Clogged Cat?? Anyone had one?
« Reply #4 on: December 12, 2005, 07:36:55 AM »
i clogged my cat up this past summer.... acted funny as hell too for a couple days till it was fully clogged.... but once it was clogged the jeep almost wanted to die... high rpm's but no power... i went from 65 on the expressway right down to 20 with the pedal floored.... ended up just emptiyng the cat out andputting it back in to look like i had a cat still..... i also had no pressure coming out the tailpipe......sure sign for me

jwrape

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Clogged Cat?? Anyone had one?
« Reply #5 on: December 14, 2005, 12:21:24 PM »
Quote from: "Jeffy"
Well, you'll have to check the exhaust and all the sensors.  I still recommend recovering the error codes stored in the computer.


O2 sensor is new. BUT it has seemed to have gotten a littlel better. Still not totally better but only noticeable around 2800-3100 rpm's. Then over 3100 or 3200 rpms it clears up.

Offline Jeffy

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Clogged Cat?? Anyone had one?
« Reply #6 on: December 14, 2005, 02:54:51 PM »
Hmm, like Tex said, check the flow at the pipe.  And monitor it for a while.
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YJmechanic

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Clogged Cat?? Anyone had one?
« Reply #7 on: December 21, 2005, 02:07:46 PM »
also posibility of the fuel pump or fuel regulator.  The is a drain back valve so fuel stays in the lines when it is shut off.  If that fails it will take longer to start and almost miss when it is cold untill it gets warmed up then works fine.  It is also possible that the fuel pump is not sending increased fuel for increased loador rpm.  I clogged my cat before and it lasted about a week untill it almost would kill the motor under load.  Just some ideas.

jwrape

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Clogged Cat?? Anyone had one?
« Reply #8 on: December 21, 2005, 03:29:38 PM »
Quote from: "YJmechanic"
also posibility of the fuel pump or fuel regulator.  The is a drain back valve so fuel stays in the lines when it is shut off.  If that fails it will take longer to start and almost miss when it is cold untill it gets warmed up then works fine.  It is also possible that the fuel pump is not sending increased fuel for increased loador rpm.  I clogged my cat before and it lasted about a week untill it almost would kill the motor under load.  Just some ideas.


WOW! You hit it on the head! When it's cold it takes a little more to get it start and it misses and really runs like it's on 2 cylinders for about 5 minutes of running it will clear up.
I don't think it is the cat anymore. Like you said it would have clogged up bad by now.

So what exactly do I need to replace? The fuel pump or regulator or filter?
The Fuel pump is either on the fuel rail or in the tank, the filter probably on the fuel rail, but where is the regulator?

This Jeep has 177k miles on it. These items probably have never been replaced.

I have noticed that the lag in rev up performance seems to be just around 2800-3100 rpms and then it cleans up but is still not extremely responsive above 2800 rpms.

YJmechanic

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Clogged Cat?? Anyone had one?
« Reply #9 on: December 23, 2005, 08:09:09 PM »
the filter is simple, it is on the frame rail near the rear axle, to clamps and one bolt.  change that regardless because it is cheap.  The next thing has to be diagnosed because it could be the regulator, which is cheap, or the pump, which is expensive.  I would have to check to be sure but I think the regulator should be on the rail.  Some did not have an external regulator though.  Some were built in to the fuel pump.  Basically you have to plug in a fuel gauge to the rail while it's cold and turn the key on, this will pump up the rail and tell you what the pump is putting out.  Check a service manual but i think you should have about 50psi, remember that the motor does not have to running for this just key on to run position.  Then turn the key off and wait five to ten minuetes and check the pressure again.  It shouldn't drop more than five pounds in that time.  if it drains out fast that is your problem and when you start it cold the lines are empty and take time to pressurize.  the rail is supposed to hold some pressure so it is not completely empty when you start it.  if you don't have the tools or can't do that much diagnostic work then take it to someone and tell them to check the fuel pressure for you.  If you have an external regulator just replace it then check the pressure if not you have to replace the whole pump assembly.  Either way let me know what you find and I'll try a walk you through it.

jwrape

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Clogged Cat?? Anyone had one?
« Reply #10 on: December 28, 2005, 12:15:01 PM »
Quote from: "YJmechanic"
the filter is simple, it is on the frame rail near the rear axle, to clamps and one bolt.  change that regardless because it is cheap.  The next thing has to be diagnosed because it could be the regulator, which is cheap, or the pump, which is expensive.  I would have to check to be sure but I think the regulator should be on the rail.  Some did not have an external regulator though.  Some were built in to the fuel pump.  Basically you have to plug in a fuel gauge to the rail while it's cold and turn the key on, this will pump up the rail and tell you what the pump is putting out.  Check a service manual but i think you should have about 50psi, remember that the motor does not have to running for this just key on to run position.  Then turn the key off and wait five to ten minuetes and check the pressure again.  It shouldn't drop more than five pounds in that time.  if it drains out fast that is your problem and when you start it cold the lines are empty and take time to pressurize.  the rail is supposed to hold some pressure so it is not completely empty when you start it.  if you don't have the tools or can't do that much diagnostic work then take it to someone and tell them to check the fuel pressure for you.  If you have an external regulator just replace it then check the pressure if not you have to replace the whole pump assembly.  Either way let me know what you find and I'll try a walk you through it.


Ok I will go ahead and replace both since they are cheap and see if that helps. I have a feeeling it will.
Thanks

YJmechanic

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Clogged Cat?? Anyone had one?
« Reply #11 on: December 28, 2005, 03:51:05 PM »
anytime