Rotten Egg/sulfur Smell?

[08AllTerrain]

Hey guys, so Ive noticed this smell every so often in my truck. I seem to only notice when I have my tune in also, did a swap for awhile to check and no smell with the stock ecm module. Any ideas what it might be? 08 Sierra 5.3, GM Exhaust/CAI with 93 Tune burning 93 octane in it..it smells like a catalytic converter smell but again, only seem to smell it with tuned module in.

[Jennabear]

Rotten egg/sulfur is definitely cats. Check your spark plugs to see if you are running rich.

[bronyaur]

I've also smelled rotten eggs when my Optima battery decided to die. The smell showed up a couple of starts before it actually died.

[nitrohorse]

Too much Taco Bell?

[greatmizzou]

I had a very bad smell like that when I had battery issues, I had a subwoofer installed into a mustang and it turned out it just bled the battery even when engine was off, very very bad smell

[jro909]

the smell also comes if you pound on the throttle....its from the cats

[08AllTerrain]

Thanks for the replies..even the Taco Bell one, haha. Guess I'll check the cats out to make sure they aren't going out.

[EvolutionX]

I was just going to start a new thread about this same issue when I came across this thread. I started having a natural gas/propane type smell in the cabin when driving my Denali. It worsens the longer I drive to the point where its unbearable and gives me a headache. From my knowledge I immediately thought, Cats. But, to be sure I took it to my local GMC dealer since if it was indeed the Cats, that should be replaced being under warranty (80,000 or 8 years). Of course the dealer calls and tells me they cant find any problems, and smell nothing. Idiots, since its very noticeable. I told them to drive it on the freeway today and it will smell for sure. So the above posters say this is a cat problem??? I have a Magnaflow after cats setup with turn down and K&N cai.

[RJG183SA]

Hey guys, so Ive noticed this smell every so often in my truck. I seem to only notice when I have my tune in also, did a swap for awhile to check and no smell with the stock ecm module. Any ideas what it might be? 08 Sierra 5.3, GM Exhaust/CAI with 93 Tune burning 93 octane in it..it smells like a catalytic converter smell but again, only seem to smell it with tuned module in.

 

IIRC, I read a GM bulletin that stated some low tier fuels contain higher amounts of sulfur and can create the excessive odor. You may want to try a top tier brand of fuel.

[EvolutionX]

Hey guys, so Ive noticed this smell every so often in my truck. I seem to only notice when I have my tune in also, did a swap for awhile to check and no smell with the stock ecm module. Any ideas what it might be? 08 Sierra 5.3, GM Exhaust/CAI with 93 Tune burning 93 octane in it..it smells like a catalytic converter smell but again, only seem to smell it with tuned module in.

 

IIRC, I read a GM bulletin that stated some low tier fuels contain higher amounts of sulfur and can create the excessive odor. You may want to try a top tier brand of fuel.

 

I run Shell 87 always and this propane/natural gas smell just gets worse.

[tanked_darren]

Hey guys, so Ive noticed this smell every so often in my truck. I seem to only notice when I have my tune in also, did a swap for awhile to check and no smell with the stock ecm module. Any ideas what it might be? 08 Sierra 5.3, GM Exhaust/CAI with 93 Tune burning 93 octane in it..it smells like a catalytic converter smell but again, only seem to smell it with tuned module in.

 

IIRC, I read a GM bulletin that stated some low tier fuels contain higher amounts of sulfur and can create the excessive odor. You may want to try a top tier brand of fuel.

 

 

Oh don't bring up top tier around here, I did that once and it started a huge arguement that never had an end.

 

I only use top tier fuel and I never use those shitty fuel injector cleaners, those are a waste of money.

[jrrod2004]

Hey guys, so Ive noticed this smell every so often in my truck. I seem to only notice when I have my tune in also, did a swap for awhile to check and no smell with the stock ecm module. Any ideas what it might be? 08 Sierra 5.3, GM Exhaust/CAI with 93 Tune burning 93 octane in it..it smells like a catalytic converter smell but again, only seem to smell it with tuned module in.

 

IIRC, I read a GM bulletin that stated some low tier fuels contain higher amounts of sulfur and can create the excessive odor. You may want to try a top tier brand of fuel.

 

 

Oh don't bring up top tier around here, I did that once and it started a huge arguement that never had an end.

 

I only use top tier fuel and I never use those shitty fuel injector cleaners, those are a waste of money.

 

 

Yes, no to the top tier issue. do what I do: pull the battery (allowing the computer to reset). Fill up on 93 octane and then drive it with a good amount of throttle. mine wasnt the cats...I guess some type of build up. Went away and has never returned (dealership was of no help at the time). I do this once a year...usually in the spring but I dont think it will work for you....

[EvolutionX]

An update on my gas/propane smell on the Denali: Got it back from the GM dealer and of course they said they found nothing and couldn't even smell anything. I ended up making a tech come with me while I drove it and then miraculously he could smell it too. The conclusion they came to was a bad tank of gas, since it has happened on this one tank I've been running. I tested the theory after paying 100 for them doing nothing of course, and ran the truck down to empty as much as I could. Filled up with Shell 87 as usual, and since then the smell HAS dissipated. I get a small whiff of it at first drive but later I really don't notice it. Weird that bad fuel could cause a propane smell, as I always thought it would just cause knock.