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Jeep 4.0 New Exhaust Egg Smell

streetxj

NAXJA Forum User
After getting a new catalytic converter and muffler installed on my 96' jeep cherokee sport, I've noticed an egg smell coming from the exhaust when I rev it hard (3000-4000 rpm revs). This exhaust has just under 100 miles of usage. It is not a horrible burnt firework sulfur smell, it is like a hard boiled egg smell. I've read that some catalytic converters give off this smell when they are being broken-in (aka seasoned). But I've also read that it could be a sign that the air/fuel mixture could be too rich. I did relocate the intake air temperature sensor to the intake box lid since it is very hot here in south Florida (80-90 degree temps) so I want to make sure that this is not the issue. I would appreciate any advice on this issue.
 
The smell might just be left overs oils and tube bending lubricant from the exhaust manufacturing processes. If the check engine light is not ON, and the O2 sensors are responding correctly when tested, as suggested already the smell will likely dissipate.

What is the reasoning behind or purpose of relocating the intake air temperature sensor to the air box ?
 
The smell might just be left overs oils and tube bending lubricant from the exhaust manufacturing processes. If the check engine light is not ON, and the O2 sensors are responding correctly when tested, as suggested already the smell will likely dissipate.

What is the reasoning behind or purpose of relocating the intake air temperature sensor to the air box ?


Oh okay. Today when I drove it for a longer period of time, I haven't noticed any egg smell.



The reason for the iat sensor relocation is explained here: http://www.angelfire.com/my/fan/IAT_sensor.html


I have airflow enhancing mods and I've noticed that my 4.0 feels castrated during heavy acceleration until the rpm climbs (lack of low-end torque). During cool weather (below 80 *F) it would run like a completely different truck. After relocating it, I did not have that issue anymore during hot weather. After installing a high flow cat (thunder bolt heavy load cat) and a 2.25 inch max flow muffler to match the dynomax 2.25 inch tailpipe, it has gained a nice amount of low end power and pulls harder across the entire rpm band. Here is my exhaust thread which explains my setup further: https://www.naxja.org/forum/showthread.php?t=1153992
 
Just want to give an update. I relocated the intake air temperature sensor back into the intake manifold and the egg smell has gone down drastically. It seems that the mod made my jeep run richer than normal. So far the only difference is a cleaner smelling exhaust with hardly any performance loss.
 
Thanks for the follow up!
 
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