2006 Down On Power

TerryD

TerryD

Mildly demented....
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Joined
May 15, 2024
Messages
158
Location
Virginia
I've noticed my LJ seems to be down on power. It does great around town but on the interstate it is struggling.

It's a 4.0L/42RLE Rubicon. Factory 4.10 gears and 265/75/16 Yokohama X/AT tires. Plugs don't have even 1k on them yet. Not overheating, running about 204°F at speed.

More than once now I've been doing 65 to 70mph on level interstate and it's downshifted to 3rd and just barely maintained speed. The last time I pressed the accelerator to the floor during this and it would not gain speed.

I had to drop down to about 60mph to get back in OD and then it would hold speed OK and stay in OD.

My LTFTs are roughly -2% to - 3% so I don't think it's a fueling issue. My CEL is on for a small evap leak and warm up codes for both primary cats.

The first thing that occurs to me after seeing the number of disintegrated primary cats is that the internals of the cats may be plugging the down stream cat and keeping the engine from being able to breath at higher RPM.

But I was wondering if there was anything else I can look at before I start stripping the exhaust system off.
 
Pull out the upper O2s and see if it has more pwr. It will throw codes for the O2s, but will run on programmed fuel parameters.
 
It felt like a new Jeep when I changed the cats. An exhaust gauge is a nifty tool and usually your local auto one will rent you one. If not, they’re relatively cheap on Amazon.

Edit: search for back pressure tester.
 
AndyG said:
There is your answer- and if you decide to pull sensors watch the clutch line or you can melt it down.
Click to expand...

not only the clutch line. all the wires on the driver side near the extra battery tray will be melted and I only drove about a mile.
 
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JKP said:
Pull out the upper O2s and see if it has more pwr. It will throw codes for the O2s, but will run on programmed fuel parameters.
Click to expand...

Y'all stop recommending this bull shit ! luckily my clutch didn't go straight to the floor until I went to turn into my driveway and all my wire looming was melted as stated above. I might of driven it a mile total with the sensors out. Just drop your cat and look for the honeycomb inside being loose. My temps were close also. But when I dropped it one of the insides was wedged down the pipe and never rattled when I did the hammer test.
 
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TerryD said:
I've noticed my LJ seems to be down on power. It does great around town but on the interstate it is struggling.

It's a 4.0L/42RLE Rubicon. Factory 4.10 gears and 265/75/16 Yokohama X/AT tires. Plugs don't have even 1k on them yet. Not overheating, running about 204°F at speed.

More than once now I've been doing 65 to 70mph on level interstate and it's downshifted to 3rd and just barely maintained speed. The last time I pressed the accelerator to the floor during this and it would not gain speed.

I had to drop down to about 60mph to get back in OD and then it would hold speed OK and stay in OD.

My LTFTs are roughly -2% to - 3% so I don't think it's a fueling issue. My CEL is on for a small evap leak and warm up codes for both primary cats.

The first thing that occurs to me after seeing the number of disintegrated primary cats is that the internals of the cats may be plugging the down stream cat and keeping the engine from being able to breath at higher RPM.

But I was wondering if there was anything else I can look at before I start stripping the exhaust system off.
Click to expand...

mine acted exactly the same but never threw a CEL. then finally it wouldn't even pull up a hill on the highway at 20MPH. My Jeep had about 103k miles on it. and when I hit it with a infrared thermo. they were fairly close in temp. New cats and she's back to running like a scalded dog, well maybe more like a tractor plowing a field :ROFLMAO: :ROFLMAO: :ROFLMAO:
 
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aFe was having a sale and I figured I needed cats ANYWAYS so if I'm pulling them to check for debris/plugging, might as well put new back so I ordered an entire exhaust system for it. At least this way it'll all be new.

Kinda a stretch but I was able to boy math and "while I'm in there" till I could justify it.

Will report back.
 
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tr21triton said:
well maybe more like a tractor plowing a field :ROFLMAO: :ROFLMAO: :ROFLMAO:
Click to expand...

It's their heritage....

422-Thomas-5-750x500-1-1-1100x733.jpg
 
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