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tkfx 04-21-2013 04:49 AM

How I found out my catalytic converter was bad!
So recently I started to hear a whistling noise coming from unknown location when I was reaching 30MPH or higher, along with a noise of metal on metal on my 04 LJ.

So yesterday as im driving down the highway, going 60mph, my jeep all of a sudden hiccups and starts flashing the CEL. Then I lost about 70% of my power on the freeway, the max i can go was 40mph. No matter how much I pressed the pedal it would not speed up. It would rev the engine higher RPM but would not speed up. Like someone took my I6 out while driving and stuffed a 2 cylinder in it. I head home and cruise 20mph up my street(speed limit is 40) with CEL light blinking. Also when I would rev the engine and try to go faster, I would hear a whistle like sound, kind of like a vacuum.

I pulled the codes and I get:

P0300 - Missfire
P0305 - Cylinder 5 Missfire
p0306 - Cylinder 6 Missfire
p0456 - EVAP leak
p0432 - Bank 2 Downstream 02 Sensor

Quite a lot of codes. So I went to my local part store and purchased a Bosch 02 downstream sensor for my p0432 code. Replaced 02 and all the codes went away. I took the jeep for a test drive and guess what. Still the engine was severly low on power. Next I figured it was the coil pack specificly over cylinder 5 and 6. Since those were the cylinders throwing missfire codes and that one coil pack controls two cylinders. Got a new coil pack and same thing, low power. Finally I decided it was the catalytic converters.

I assumed it was catas because the missfires were not really missfires. There was no engine shake and the engine ran fine at idle.

So after much struggle and stripped bolts, me and my dad got the catalytic converters off. I was shocked at what I saw inside:

As you can see, the actual converter webbing things is suppose to look like picture 2. In picture 3 the webbing broke down and fell apart and clogged the hole. That part of the cat was connected to cylinders 4-6. So this was the main reason the computer was calling missfires. I tried the "bang on your cats and see if you hear any loose metal" but that didnt work for me.

Anyone reading this in the future, if you have these symptoms then its most likely your cats. At first I was hessitant to believe it was the cats because my jeep is 58k Miles and only a 04. No reason for the cats to go bad. Well I was wrong. Too bad I was just 1 year shy for my 8 year warrenty on the cats.

wwch99tj 04-21-2013 07:56 AM

Pics not working... glad you figured out your problem though

jgorm 04-21-2013 10:21 AM

Pics work for me. I had the dealer replace them under the 8yr 80K mi (I think that's it). They said one of my cats had nothing in it! I knew one was bad because I was seeing 150F differences in their temps.

2000wranglerguy 04-21-2013 10:27 AM

glad you figured it out, cats can also smell like rotten eggs and they will also glow from the heat... just a couple of tips.

SeVeReDiStOrTiOn 04-21-2013 11:20 AM

Yikes. Have you noticed a raw fuel smell? You might want to check the plugs on that bank...usually raw fuel getting to the cat will cause that melted look.

tkfx 04-21-2013 02:30 PM

The cats never smelled of anything either. I did a sniff test from the back and the smell was just like any other vehicle.

I have not smelled any raw fuel and I haven't checked the plugs, I will take a look at them when I change out the coil pack.

Also does anyone know if its only the california jeeps that have the 3 cats or if all of them come with 3.

SeVeReDiStOrTiOn 04-21-2013 05:14 PM

As far as I know only the CA jeeps come with the mini-cats.

tkfx 04-21-2013 06:14 PM

Well I woke in the morning to seemy dad has opened up the problematic mini cat and and cleaned the inside out and welded it back in. Jeep runs great and no CEL codes. Dam California and their laws.

tkfx 04-22-2013 12:15 AM

Here are better links to the pics.

Green03TJ 04-22-2013 07:40 AM


Originally Posted by SeVeReDiStOrTiOn (Post 3664940)
As far as I know only the CA jeeps come with the mini-cats.

Not sure, but I think all the later TJs had the mini-cats.

UnlimitedLJ04 04-22-2013 07:54 AM


Originally Posted by SeVeReDiStOrTiOn (Post 3664940)
As far as I know only the CA jeeps come with the mini-cats.

2000 was the split year. some got 3 cats, some got 1 (CA vs non-CA). All later models got 3-cats & four O2 sensors.

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