06 LJ exhaust upgrade

lowell66dart

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Supporting Member
Joined
Apr 28, 2024
Messages
32
Location
South Louisiana
Bought this LJ about two months ago and I have been doing this and that to get it running a little smoother and normal maintenance, tires, shocks etc. It would throw codes relating to O2 sensors. They would clear with my scanner but a few days later come back. One repeated a little more than the other and changed out one sensor and that one went away. When changing the sensor I noticed that my exhaust was moving a bit. I think it was sucking air ahead of the precats. I was able to tighten each bolt about 3/4's of a turn. No more loose exhaust pipe. Got lucky with those bolts. This made me start looking at exhaust kits as everything is original and the muffler looked rough. Didn't want nothing much louder and I don't like drone and was not spending $600 for a muffler and tailpipe. Did a bunch of looking around and this kit had very good reviews and the price was too good to be true. Finally pulled the trigger on this kit. It was ordered from the MBRP store for $220.49 shipped. Ordered on a Thursday and came in Saturday afternoon. I had my old system unbolted and waiting to remove. It came packed very very well in a heavy cardboard box with no lettering on the outside to foil the porch pirates. The hardware was in heavy ziplock type bags and the clamp was a nice band clamp. It's probably about four pounds lighter that the stock system for you guys watching your weight. Went on easy but I do have a four post lift. Didn't drive it much last night as it was raining but it a bit louder but I bet my wife will not notice. I didn't take any pics because Extreme Terrain has a really nice install video on their website. Anyway here is what I ordered. When I get to drive it a bit I update this.

2.5" Cat Back, Single, AL, Jeep Wrangler (TJ) Unlimited, 4.0L I-6 2004 - 2006

S5520AL
Brand: MBRP​
 
I noticed the same thing day the exhaust pipe has a little play. I didn’t spend too much time investigating it since it isn’t throwing any codes. When I am at higher elevations for the day around 2/3rds through the day I get a “pending” P0171 or P0174 running lean if I recall correctly. Goes away when I get back home. I am wondering if the loose exhaust is causing it, since no CEL.

I’ve thought about seeing if I can tighten the bolts / nuts but don’t want them breaking so have left it alone.
 
Danarch I would get the right six point socket, extension, universal joint etc and carefully try to tighten the bolts. The indication that it's running lean will throw more fuel in and running rich is not good for the engine or milage.
 
The exhaust really sound nice. At idle it has a deep tone and on the road it sounds great. I can still hear my tires and they are brand new BFG AT's.

With the new muffler being shorter I have a bit of room between the back of the skid plate and the new muffler. I really don't like the location of the third cat sitting right next to my auto tranny. I picked these Magnaflow universal cats off of Marketplace for $130 for the pair. One is going on the Jeep later this week. I'm going to put it as far back as I can. I cut the two bolt studded flange off the old muffler and I am going to put it just forward of the skid plate to make the exhaust easy to remove.

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Danarch I would get the right six point socket, extension, universal joint etc and carefully try to tighten the bolts. The indication that it's running lean will throw more fuel in and running rich is not good for the engine or milage.

Thank you for the input. I agree and understand. If it was something permanent I’d certainly be looking into it. But it only happens at higher elevations and then it’s only a “pending”. I’ve an electronic devices which plugs into the OBDII port and I can select from about 80 gauges and I have the option for “pending” codes to alert me. One time the CEL light came on. Next morning was off and hasn’t come on again.

It will need to be looked at though.