How does the exhaust smell?

Anyone do a retune to make the car run n smell better?

 

Do you have a garage?

It smells like pure rotten egg's fart.

I would not have any of my cars without a cat-converter.

 

A friend of mine removed the cats on his 92. It smelled so bad he was embarrased to drive it on dates.

 

The real question here is..."why?"

If it's something your thinking about doing to get more power, it's A) not worth it, and B) very difficult to find someone to help you with this, at least professionally, and of course C) your resale potential has been greatly narrowed.

*note--if you do find someone that will do this, chances are you will wind up with a 'hack job' on your exhaust system and of course no recourse because, "they never met you in their life".

If it's because the cats have burned up, then the next question is..."why"? Most of the time these fail because there is an improper running condition in the engine. Too rich, too lean, etc. In which case you want to find the issue here. Then replace the cats to spec. Or, if you have installed a Hotcam or made similar changes to the engine, this can cause the cats to burn up, see above. In that case, look for some high flow cats with metallic materials as opposed to ceramic.

If you remove the cats, you will notice a rich exhaust smell. Yes, you will want to find someone to tune the car. For a couple of reasons, one to reduce this smell, but also because your fuel ratios are going to be all over the map because your computer is going to constantly try to make adjustments to please the O2 sensors.

Just my $.02 and probably all it's worth.

 

You will notice a strong fuel smell. Not great on a street car.

 

This isn't complicated. Go "visit" an older domestic, V8 car that never had cats; any pre mid-'70's car....and smell the exhaust. What do you smell? You smell...exhaust. Smells just about exactly like your lawn mower, or the exhaust from a 4 stroke boat engine. There is no "rotten eggs" smell at all (that is cause BY a cat, that isn't functioning correctly), and it's not terrible or embarrassing (if the engine is in a decent state of tune), but it is certainly more noticeable than the smell with a properly functioning cat.

Also, a well running, well tuned engine can produce less emissions than a poorly running engine with a cat, so the car, by itself, guarantees nothing.

 

Cost could be a factor. It is much cheaper to take a clogged cat and hollow it out as opposed to buying a new cat if your old one is suspect.

I'll bite. How much difference will it make to the O2 sensor since the sensor is upstream? If you are talking about a car with sensors before and after the cat, probably need to get O2 sims.

 

Maybe if it is idling and the wind is right but I don't really smell my exhaust.

 

Like I said, it's about as "offensive" as any older car, or your lawn mower.

 

the LTx cars have O2's in front and behind the cats. So a tune is needed if for no other reason to keep the SES light dark. However, and I can only really speak to the OBDII cars, the car will constantly try to adjust fuel ratios if not tuned to run catless. How much does it really effect driveability, can't say for sure, at least not long term effect.

And good luck finding O2 sims, they are illegal, so no one in the aftermarket sells them anymore. Don't think anyone makes them either.

 

Who cares how it smells...I just hope you have some extra cash laying around to pay the fines....WW

Title II of the EPA Clean Air Act (Enacted Jan 1 1988) there are multiple regulations concerning the use or misuse of aftermarket catalytic converters, or the removal and/or modification of a stock catalytic converter. According to various parts of Section 203, all aftermarket catalytic converters must be EPA certified, and your car must have a gas conversion device of some manner. If not, both you and the installer are punishable of a Federal Offense by Section 205 (a). The operator's fine can be no more than $2,500 and the installation agency no more than $25,000.

 

I might be wrong but I thought the upstream sensor is for adjustment and the downstream one is for cat converter efficiency? IOW, is the rear sensor used for adjusting fuel ratios or just to tell if the cat is plugged up?

http://www.latemodelrestoration.com/...FctAMgod3msAzw

 

This is an untrue statement, the 02's are ahead of the cat and the engine makes fueling adjustments based on those O2's. The AFR is held at stoich before it gets to the CAT. If you have a 1996 then there are rear O2's that need to be tuned out but it will not change the mixture.

 

Hmm, not what I was I told, but okay.

 

Why would you think the O2 sensor behind the cat would be used for fuel trim adjustments? What is the front sensor for?

 

No emission testing for my 92 zr1. Was just curious as i'm in the process of purchasing long tube headers and the obx one's i'm looking at seem to have too long of a collector flange to install catalytic converters.

Thanks for the feedback.

 

...And with that said, I'll close this one down.