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Sulfer smell after exhaust upgrades

theksmith

theksmith

NAXJA Member #1072
Location
Phoenix, AZ
After installing new exhaust components, under full throtle exceleration, my truck reeks of the rotten egs sulfer smell usually associated with the cat. It didn't do this before, or at least was completely unnoticible in the cab.

I put in rusy's exhaust (flowmaster 50 delta + mandrel 2.5" tube), and a MagnaFlow cat at the same time (91006 http://www.car-sound.com/catalog/universal/910.aspx).

Did I get to small of a cat? The chart on that page says it will handle a 4.2l engine in a 4500lbs vehicle. Or is my truck running to rich (or is it lean)?
 
sulfur smel is usually the cat but how long have you had it on for any of the wacky exhaust smells usually take a week or so to go away
 
Been over a month now... and it's immediately noticible under full throttle (like passing someone doing 85). But under standard driving conditions, or even normal acceleration, there is absolutely no smell.
 
You are burning the undercoating off of the bottom of the truck with the flowmaster. They run EXTRMEMELY hot. Could also be the interior carpeting underlayment. Either way, you need some heat-shielding.
 
CRASH said:
You are burning the undercoating off of the bottom of the truck with the flowmaster. They run EXTRMEMELY hot. Could also be the interior carpeting underlayment. Either way, you need some heat-shielding.
Click to expand...

I agree, this was happing to a freind of mine with a Flowmaster 40-series. It was one of the reasons why I didn't purchase one. The second was, IMO, they make the 6-cyl Jeep's sound like a civic with a coffee can. I can't say the same about my Dynomax; Good Sound, and it keeps cool.

So, if you like the sound, do as CRASH says and add some heat-sheilding. :D
 
I'll look into the heat shielding, I just assumed the sulfur smell was a cat issue.

RCMan, The flowmaster I have is the 50 series Delta and it actually does have a nice tone. The 40 or even the 50 non-delta is loud and crackly. Strangely enough, I think the 40 series sounds like a redneck tractor truck but reminds me of those coffee can Civics at the same time! Two groups that hate each other!
 
CRASH said:
You are burning the undercoating off of the bottom of the truck with the flowmaster. They run EXTRMEMELY hot. Could also be the interior carpeting underlayment. Either way, you need some heat-shielding.
Click to expand...

Does this make sense that it would only get hot enough to smell under full throttle and then go away immediately after going back to cruizing speed??

Also, the new flowmaster does sit directly below the aluminum sheilding that was already in place for the old exhaust... how do i add more - what are my options here?

Thanks in advance.
 
i know flowmasters/cats run hot from personal experience, exhaust got bashed up on the the floor pan when wheeling, and my carpet caught on fire on the ride home...not a fun smell
 
kristoffers said:
Does this make sense that it would only get hot enough to smell under full throttle and then go away immediately after going back to cruizing speed??


Thanks in advance.
Click to expand...

That's a symptom of a hot cat or FM or both. They cool very quickly under light throttle.

Remember, when you are at WOT, the mixture drops from 14.7 to 1 to about 13 to 1, a rich condition that is designed to yield safe combustion chamber temps and yield a bit more power under max spark advance. Still, combustion chamber temps go way up to about 1100 degrees on long pulls, where as under light throttle they are about 4-500 degrees.
 
Crash, it does make perfect sense now. I'm still suspicious that if I purchased a cat that was not designed to handle that much fuel/flow, then when running rich at full throttle it would overwork the cat and produce the smell.

However, I'm certainly going to try the shield first. The cat has it's own little shield attached to it, and there is an aluminum shield already on the floorpan above the flowmaster (stock). Is this an aluminum sheet with insulation inside? I saw another thread on here about shielding, but it was just the facotory stuff.... Where can I get similiar material to make my own? I guess I'll put double sheilds above the entire cat-back...

Thanks.
 
im running a flowmaster delta flow 40 series and yes it does get very hot on the rear passenger floor...i took my carpet out too..no heat shield either..i cook breakfast on my way to work..sunny side up eggs attribute to the sulfur smell in my rig..

..and it definitely doesn't sound like a civic with a coffee can or a tractor....it sounds like a 4.0 with a throatier, more free flowing muffler that's built like a skid plate..thats been quoted all over this site and i can attest to its truthfullness
 
any updates on making the smell go away?
ive been running with just metal floors for a while, and just put in new carpet.
2 days after installing the carpet i get rotten eggs.
 
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