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Noticed a diesel smell in my Dads 2016 GMC DURAMAX DENALI. Wondering if anyone else has had issues with this and how to fix it. Also on a side note. It’s recently been deleted and got a 5 inch flo pro and GDP tunes. Everything is great except it just reaks outside especially when my dad remote starts its to let it warm up in the morning it stinks up the whole drive away. Got told that by adding the CAT back on the smell should be reduced significantly and drone would go away. Any help? Sorry bit of a newbie. just trying to help my dad out lol thanks guys
 

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Put the stock cat back on the drone and diesel exhaust stink will taper off some, that’s what I did after 5 years of suffering.
Aftermarket cat will NOT help, been there tried that.

If he has raw diesel smell in the cab then pop the hood and look for leaks.

If it’s the raunchy exhaust fumes your talking about roll up the windows and select recirculate on the ac controls.
Don’t allow the not so fresh outside air in from your stinky exhaust.
 

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Put the stock cat back on the drone and diesel exhaust stink will taper off some, that’s what I did after 5 years of suffering.
If he has raw diesel smell in the cab then pop the hood and look for leaks.
If it’s the raunchy exhaust fumes your talking about roll up the windows and select recirculate on the ac controls. Don’t allow the not so fresh outside air in from your stinky exhaust.
Can i put the stock CAT back on even while deleted and with the new exhaust? someone said i can’t do that, “it doesn’t work that way” someone told me.
 

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Can i put the stock CAT back on even while deleted and with the new exhaust? someone said i can’t do that, “it doesn’t work that way” someone told me.


I’ve had my catalytic converter back on for about 6 months. Works good and cut the smell down quite a bit. There isn’t much of a drone and it lowered the turbo noise a lot. That is on an LMM motor. I had no difference in mileage or power loss. I don’t know about the LML setup. My 2015.5 isn’t deleted. I think the DPF and catalytic converter on them are one piece with no way of separating them. A person could probably buy an after market catalytic converter.


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I believe it's the SCR that is together with the DPF.

The DOC (diesel oxidation catalyst) is separate, and ahead of those.
DOC is what is often referred to as the catalytic converter
 

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I think the DPF and catalytic converter on them are one piece with no way of separating them. A person could probably buy an after market catalytic converter.
Sent from my iPad using Tapatalk Pro
I don’t know about the exhaust on the 2015, you’ll need to get underneath and look.
The cat should be a separate piece from the DPF, it could be one longer section.
If so then you’ll have to separate the 2 by cutting, I think a few others have mentioned it will separate from the DPf section.

As I already mentioned a aftermarket cat will NOT help with drone and/or stink, I’ve already tried that.
A aftermarket cat is on a Diamond Eye (no so) quiet tone frontpipe is in my shed, the one on top.
Bottom one is a DE quiet tone W/O cat, both are in my shed.

Bottom picture should be what your exhaust looks like, the doc is the cat like mentioned in the previous post.
 

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I think the DPF and catalytic converter on them are one piece with no way of separating them. A person could probably buy an after market catalytic converter.
Sent from my iPad using Tapatalk Pro
I don’t know about the exhaust on the 2015, you’ll need to get underneath and look.
The cat should be a separate piece from the DPF, it could be one longer section.
If so then you’ll have to separate the 2 by cutting, I think a few others have mentioned it will separate from the DPf section.

As I already mentioned a aftermarket cat will NOT help with drone and/or stink, I’ve already tried that.
A aftermarket cat is on a Diamond Eye (no so) quiet tone frontpipe is in my shed, the one on top.
Bottom one is a DE quiet tone W/O cat, both are in my shed.

Bottom picture should be what your exhaust looks like, the doc is the cat like mentioned in the previous post.

I’ve been told by multiple people now that an aftermarket CAT (5 inch) will reduce the smell. Not sure what to do anymore just really trying to get rid of the smell. we have a 5 inch exhaust and don’t have the stock CAT anymore.
 

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I’ve been told by multiple people now that an aftermarket CAT (5 inch) will reduce the smell. Not sure what to do anymore just really trying to get rid of the smell. we have a 5 inch exhaust and don’t have the stock CAT anymore.


What I meant as an aftermarket, was by replacing with an older OEM catalytic converter, from like an LMM. Guess I should have been more clear. The shop that installed mine, took the old converter and replaced the muffler with the converter. As I said in the earlier post, I wasn’t sure about the LML. I haven’t actually looked a it, because I’m planning on keeping it stock. At one time, I thought I would delete it, but looks like it would have to be done from out of country to do it now. All I was going on, on the LML exhaust, was what I had read on here on other posts. If it is separate, I would try to find someone who had deleted their’s and buy their old exhaust.


Sent from my iPad using Tapatalk Pro
 

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Thread Title said:
Interior cabin diesel smell
except it just reeks outside
It’s recently been deleted
So, which is it? In or out?

Inside the Cabin? If so, is it a new problem? Or only after the exhaust mods done?
(you may have a leak up front)

It's a DOC, not a cat.
Cold start, if you don't have a DOC, it'll water your eyes standing at the rear.
 
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