Millermatic

The car continues to come along (The speedometer works!)... but I'm still chasing an intermittent smell.

I've got a 3" bolt-together exhaust from Lindsay with a Magna-flow muffler. The system includes their "high-flow" catalytic converter... which isn't California compliant.

Here's my thought: You can look straight through the Cat. Given the amount of free area (lots) and the cost of the cat (not much), I'm beginning to wonder if the Cat is doing much of anything... and I'm smelling that... lack of working.

Anyone out there have this setup? And do you have any issues with stinky exhaust? Anyone tried the Lindsay 3" CA Compliant Cat?

For some context, I've replaced my rear hatch seal. I don't think I have any fuel leaks (doesn't smell quite right anyway). I've fairly thoroughly gone over the exhaust connections. I don't _think_ I have a leak. I can smell it if I'm driving slowly or in an enclosed area with the windows open. Seems worse when car is cold.

Thanks for any thoughts...

968to986

I don’t have any experience with high flow cats, though I’d like to try one eventually. My hollowed out cat produces a lot of smell. I will say though that in changing out my shift boot recently, I also installed a new inner rubber boot (old one was cracked), and it did help with exhaust smells in the interior. Good luck!

Millermatic

Thanks. That’s a start. My shift boot and foam sound isolator underneath it are both new.

I actually get very little smell inside. It’s through the (open) windows if I’m at a stop.

I can testify that the “replace your rear hatch seal” helps on interior smells!

CyCloNe!

If you are getting smell inside the cabin there’s only a few options.

1) Exhaust leaks
2) Shift boot or inner boot
3) Hatch seal

A high flow cat when warm should have no extra smell or very small. Cats function comes in to play when hot so that is why you get odor when cold. This should really only be noticeable if someone is behind you, not inside the cabin. Lindsey generally uses band clamps and band clamps do tend to leak some. You probably have a leak some where. Double check all sealing locations maybe even have a friend push the gas a little as you search. Since it’s a full exhaust check your front connection and cat area.

Millermatic

Thanks. I get very little, if any smell inside... unless I have the windows open. I’m guessing any smell I get inside (when the windows are up) is from my recent removal of the covers over the fuel filler neck in the back of the car. I need to do a bit more sealing before I put the trim and carpet back in.

The worst is when I’m _backing_ out of my long (and tight - there are adjacent buildings) driveway. At which time the car is cold and I’m backing through exhaust. I often have the windows open so I can lean out to make sure I’m not going to hit something. (My driveway is a bit of a pain in the rear). I’ll also notice it at a stop in traffic with the windows down.

It’s not as bad when the car is hot... which would make sense if it was the Cat. I’m just wondering if this particular Cat (which isn’t 50-state compliant and looks like it was made with a screen window that wouldn’t keep a (small) bug out) is doing much.

I”m also curious to hear from people not using a Cat. I assume it smells?

CyCloNe!

I ran cat-less on a 3” exhaust for my 951 and run cat-less on my 944 v8… the v8 is worse in odor lol. Both did have smell, I was told it smelled like an old motorcycle lol. Wife tells me I smell like a weed eater every time I drive and a strong fuel smell. The reality is even with a 3” exhaust with a cat the car needs to be tuned. If tuning is done it will help the odor a good amount and the above things checked as well. Since you just getting a small amount I wouldn’t worry too much.

joseph mitro

I have the Lindsey Racing 3" exhaust with a straight pipe (no cat) on my 944 turbo engine and it does smell a good bit. i just don't notice it much because i"m going forward, but it's not a car I would drive to work every day and expect to smell good

CyCloNe!

It’s a smelly smelly… that smells…
smelly lol

Millermatic

Thanks for the input, all. I'm toying with the idea of trying a 3" "CARB" cat in place of what I have. The smell isn't _horrible_ but I'd like to reduce it (the family complaining isn't the least of the reasons). I'll post back if I learn anything.

I am a bit confused about what's out there... I can find a 3" Magnaflow "Pre OBD II California-compliant" for 200-ish. Then there is the OBD II CARB-compliant Magnaflow which is over twice that. I've got is the "non-CA" 3" Magnaflow... which is about $100.

DiegoR

I have bought a 951 with some goodies including a 3" full exhaust with CAT bypass. Forget the Magnaflow junk CAT's they are worthless piece of junk. Go Kooks Green or Gesi Sport CAT. I have purchased many Gesi CATs in the past retrofiting some of those non EPA version which works great for the fumes/smells, which drive me crazy in a older car and can't live with that,

I'm about to install this one : 10030

OBD2 - Non-EPA - G-Sport Emissions Catalytic Converters

https://gsportbygesi.com/high-perfor...tems-products/

Millermatic

Thanks, I'll check those out. The Magnaflow I currently have certainly _is_ a worthless piece of junk... but I'd like to think that a CARB-compliant cat (or at least a "Pre-OBDII" California-compliant cat) wouldn't be junk.

Doyle623

I have a B&B 2.5" cat-less exhaust and I'm considering adding a high flow cat to cut down on smell. The Kooks Green cat is pretty pricey (~$650) and G-Sport better at ~$350. The B&B exhaust is made with T304 steel, but I can't confirm if the cats are made of the same /similar material. Could your average muffler shop simply cut out a length of exhaust and weld the cat in place?

curtisr

You can count on a new catalytic converter to produce a distinct odour for a good six months.

Millermatic

I don’t get why. Every new car I’ve purchased has had... a new cat. That didn’t smell. Can you expound on that?

curtisr

My offerings are based on anecdote, garage owner's experience and not much else. It may well be a result of the size offered up as a replacement given the propensity for folks to ask for the cheapest, 'universal' offering. The smell appears to be, however, a result of incomplete catalysis (?) of sulphur compounds. This can be a function of a low number of heat cycles, engine not operating at peak operating temp, high-sulphur gas or according to many the removal of the cat's 'lining' as time goes by (what ever that is). I installed a new cat converter in my 924s and promptly went on a long road trip. The smell was bad enough for my wife to demand I stop in a Mr. Muffler for an opinion. The tech laughed and said 'not to worry but it can take months'. It did.