Exhaust Hiss and HEAVY Exhaust Smell After Deletes

[tobyw]

After a several year hiatus, I am back in the diesel truck game, this time with a 2012 Megacab Laramie. When I picked it up a couple months ago, it was bone stock with ~59k miles. It rolled over 61k last week, and I went ahead and installed a Sinister EGR and throttle valve delete, as well as a Flo-Pro downpipe and DPF/cat delete pipe going into the stock muffler. I'm using an H&S Mini-Maxx for now.

My issue is that I've now got a very audible hiss from the tailpipe, and the exhaust smell is atrocious. It reminds me of the old John Deere we had on the ranch growing up, and while I can appreciate the fond memories it induces, the smell is NOT what I was after getting back into a diesel pickup... Are either of these things common with an EGR/DPF deleted Cummins? When installing the Mini Maxx for the first time, it specifically asked if the DPF was still present, but there was no mention of disabling the EGR functionality? Is that normal? I don't have any error codes or anything and it seems to run fine, but the hiss and smell are making me seriously consider going back to stock???? I appreciate in advance any input or ideas on what to check.

 

[shorthorn]

I can't help but laugh at the irony... you delete the emissions control equipment and then complain about the emissions of the truck... Its been a long day.

 

[Deleted member 995608]

A local rancher buddy of mine has a 2011 that's deleted. His exhaust has an interesting hiss in the exhaust note also, but it's not horrible. Maybe double check the fitting along the pipe to make sure all fasteners are tight and check for leaks.

I'd call Mini Maxx and ask for additional advice on the exhaust stank.......

 

[spoon059]

I can't help but laugh at the irony... you delete the emissions control equipment and then complain about the emissions of the truck... Its been a long day.

Yea, I was thinking the same thing...

 

[HWTG]

Anytime you delete emissions equipment on any diesel, they are going to stink, what did you expect?

 

[promisedland]

Did your truck have a CAT?

 

[tobyw]

To be blunt, I wasn't sure what to expect, thus my question... Thanks for the helpful replies.

 

[tp0d]

Anytime you delete emissions equipment on any diesel, they are going to stink, what did you expect?

i think he meant a smell like an older truck, pre-6.7L. I had a 1996 12v, that the exhaust had a decent, recognizable smell. Way better than bein stuck behind a powerstroke. those (older) trucks __staaaank_! nasty acrid smoke

Ive had smells like burnt marshmallows from my 16, particularly when using the high idle warmup when the air is moist. Definitely a clean diesel, doesnt even smoke when I jump on it. But i miss the 20-22mpg from my 96

-j

 

[tp0d]

To be blunt, I wasn't sure what to expect, thus my question... Thanks for the helpful replies.

toby--

I deleted my old 10, then did egr 8mo later (in a futile attempt to find a coolant/boost leak, it was the turbo)

After i did the exhaust work, it was much louder, and the hiss was really obnoxious when warming up in the mornings. Almost couldnt run it, ****** off the neighbors.

Dunno what you can do bout the smell, i guess its how these new trucks run with the multiple injection cycles. I do miss the old familiar diesel smell. The hiss i believe is from the VGT turbo. Mebe need a glasspack?

-j

 

[tobyw]

toby--

I deleted my old 10, then did egr 8mo later (in a futile attempt to find a coolant/boost leak, it was the turbo)

After i did the exhaust work, it was much louder, and the hiss was really obnoxious when warming up in the mornings. Almost couldnt run it, ****** off the neighbors.

Dunno what you can do bout the smell, i guess its how these new trucks run with the multiple injection cycles. I do miss the old familiar diesel smell. The hiss i believe is from the VGT turbo. Mebe need a glasspack?

-j

Thanks a bunch for the insight. I was wondering if the hissing noise had something to do with the VGT, as it almost sounds like the exhaust brake is very lightly engaged, if that makes any sense... The noise when it's warming up now with the exhaust brake engaged is like a Hoover on steroids :-laf

The smell is what really bothers me though. I get that removing the DPF and cat effectively eliminates the "cleaning" of the exhaust, but I guess I just don't remember the older diesel pickups ever having this obnoxious of a diesel smell to them?? I suppose I'll get used to it sooner or later, but I thought I'd ask if anyone else had a similar, marked change, in their exhaust after doing the deletes. All I ever read about is how happy people are with their trucks after the deletes, I've never really read about the downsides for us picky folks :{

 

[Deleted member 995608]

I can't argue with deleting 07.5 - 2012 Dodge/Rams 6.7's. Before buying our 2016, which will remain intact, I was looking at some 11's & 12's, and I had full intentions of deleting all emissions.

 

[TRAMPLINEMAN]

Definitely a clean diesel, doesnt even smoke when I jump on it.

-j

Just like all the TDI's on the road.

 

[bmborum]

Do you have any other issues OP?

I ask because i have the same model year, same everything with the exception of the MM....

When I got done with the deletes a week ago all was well, no codes, perfect.

A week later I am developing a rattle coming from the center dash to the glove box area....sound like the most subtle and obnoxious rattle....like something rattling in your cup holder....ONLY at idle. Raise it 20-50 Roma and it stops. Check all the exhaust clamps, turbo clamp, but I noticed the bracket on the EGR delete is rattling at almost the same frequency as it sounds....tightened everything....nothing

 

[tobyw]

Thankfully no issues so far. I can't imagine what would be rattling, as it sounds like you've checked all of the things that were manipulated during the delete? Sorry I can't offer any help, or even bad advice :-laf

Other than the exhaust smell, the only nitpicking I have on the whole thing is the routing of the new coolant hose vs. the factory crank case vent hose - they rub on each other. I plan to replace the factory vent hose with a new chunk that is about 2" longer to alleviate the rubbing.

 

[KenHwy61]

What kind of MPG increases have you guys seen since deleting? I got a good increase just by unplugging the EGR valve and was wondering if it is even better to do the full deletes.

 

[BarryG]

I was just at a dealer over the weekend looking at a new truck. As we were walking to the back lot a truck came rolling in right behind us at idle. It had an extremely loud whistle, hiss, didn't notice any smell. The saleslady was telling us it was the fastest most powerful production truck Ram ever made from the factory had over 600hp, over 1000tq and they (the dealer) just put a straight pipe exhaust on it. Then went on to say it wouldn't pass emissions here and whoever buys it will have to take it out of state. I just looked at my wife with an exasperated look. The truck looked great I do not know what year it was certainly 2010 or later the whistle or hiss was extremely loud sounded like a freaking jet engine you could hear all the way across the very large parking lot. I know if I had to wake up to that everyday the neighbor more than likely would have ended up with the "ol' potato in the tailpipe trick" said in my best Eddie Murphy voice. Hopefully yours is nothing near the loudness of that truck. It was downright loud and the pitch was at least for my ears to high and no way I could have driven that thing more than a few blocks without earplugs.
That was just the beginning of the saleslady's BS she had a lot of stuff right but also a lot wrong when showing us the new truck.

 

[TRAMPLINEMAN]

It was a banana in the tailpipe!

 

[BarryG]

Dang it don't I feel like a moron for referencing a movie clip and got it wrong and one of my favorite movies to boot. Since I don't like to think of myself as a moron regardless of the reality I am going to put the blame on age is starting to affect my memory.

 

[tobyw]

What kind of MPG increases have you guys seen since deleting? I got a good increase just by unplugging the EGR valve and was wondering if it is even better to do the full deletes.

So far I'm still on the same tank of fuel, so I can't comment on any potential increase in economy. I am, however, ​hopeful to see some increase...

 

[KenHwy61]

Let us know how it turns out. I have been considering the Raceme Ultra and some real world feedback would be great. Thanks.