exhaust smells like hell

[senseikrang1]

I notcied this past week the car has been smelling like hell....I just got the oil changed, I always use 94 octane, but my exhaust on the supra smells terrible....anyone experience anything like this? What is causing it?

 

[suprahero]

It's not going to smell like daisies I know, but what kind of smell is it? Oil? Gas? Coolant? Shit?............:biglaugh:

How is it running? Is it throwing any codes?

 

[akito]

Can you please be more specific? Like what suprahero said, what kind of smell would give us more details to try and help you.

 

[Poodles]

I'm thinking his cat's going out if it smells really bad...

coolant doesn't smell horrible...

 

[JASONA70]

the smell of bhg ::bhg:: ::bhg:: ::bhg:: ::bhg:: ::bhg::

 

[jdub]

You mean like rotten eggs? = Bad CAT

 

[senseikrang1]

You mean like rotten eggs? = Bad CAT

Yeah rotten eggs, someone told me it could be the o2 sensor as well........is that even possible?

 

[senseikrang1]

It's not going to smell like daisies I know, but what kind of smell is it? Oil? Gas? Coolant? Shit?............:biglaugh:

How is it running? Is it throwing any codes?

It runs perfect, only thing is when I park it the fumes are unbearable, rotten eggs

 

[Mk3runner]

its the cats... replace them, but first find out why the went bad in the first place.

 

[jdub]

From Winkipedia...Google is your friend
I highly doubt a bad O2 sensor is the cause of your problem...could be a contributor though. Especially is it is causing a lean AFR.

Catalyst poisoning and deactivation

Catalytic converters become ineffective in the presence of lead due to catalyst poisoning. Therefore, vehicles equipped with catalytic converters must only be run on unleaded gasoline, and it is this fact, as much as concerns about the possibly harmful effects of lead emissions, which caused the end of pump-available leaded gasoline in countries where catalytic converters have been in common use for many years. Leaded "race only" fuel is still used for non-catalyst vehicles in some countries. Catalyst poisoning occurs when a substance in the engine exhaust coats the surface of the catalyst, preventing further exhaust access to the catalytic materials. Poisoning can sometimes be reversed by running the engine under a very heavy load for an extended period of time to raise exhaust gas temperature, which may cause liquefaction or sublimation of the catalyst poison. Common catalyst poisons are lead, sulfur, zinc, manganese, silicon and phosphorus.

Zinc, phosphorus and sulfur originate from lubricant antiwear additives such as ZDDP; sulfur and manganese primarily originate from fuel impurities or from additives such as Methylcyclopentadienyl Manganese Tricarbonyl (MMT), respectively. Silicon poisoning in automotive applications is the result of engine damage, such as a faulty cylinder head gasket or cracked casting, admitting silicate-containing coolant into the combustion chamber. In stationary engines silicon poisoning is more often caused by the use of methane landfill gas as a fuel.

Removal of sulfur from a catalyst surface by running heated exhaust gases over the catalyst surface is often successful; however, removal of lead deposits in this manner is usually not possible because of lead's high boiling point. In particularly bad cases of catalyst poisoning by lead, the catalytic converter can actually become completely plugged with lead residue.

A variety of conditions may cause the catalyst to overheat (heat deactivation) and potentially to melt down. Some factors that can cause this are:
lubricating oil in the exhaust system (caused by engine wear, or by damaged rings or valves)
an engine misfire or ignition failure (causing unburnt fuel to enter the exhaust)
a cracked exhaust valve (again, causing unburnt fuel in the exhaust)

Overly rich fuel mixtures are not usually a problem - there is too little unused oxygen for the exothermic reaction to be large enough to cause damage. A slightly lean of stoichiometric mix is far more dangerous, as the oxygen level is elevated, allowing a very large exotherm, and many engine manufacturers design "rich excursions" as a catalyst protection measure in the engine control software. In the early days of catalyst-equipped cars, (primarily in the USA) before the advent of sophisticated engine management systems, it was necessary for fuel/air mixtures to be significantly richer than had hitherto been the case to allow the catalyst to work effectively. This contributed to the very poor fuel consumption figures achieved by such cars.

Engine misfires can overheat and destroy the converter as the excessive amounts of unburned fuel are broken down within it, especially when the engine is under heavy loads. Vehicles equipped with OBD-II diagnostic systems are designed to alert the driver of a misfire condition, along with other malfunctions, using the Malfunction Indicator Lamp or "Check Engine" light. If the misfire and engine load can produce heating severe enough to cause catalyst damage, the MIL will flash until the misfire or engine load is reduced.

 

[Mk3runner]

what he said.

 

[marlonvip]

Hi Guys,

Im in the process of building a complete 3 inch turboback exhaust system,
Does this mean that if I ditch the Cats my exhaust fumes a gonna smell like rotten eggs??

Marlon

 

[Rich]

Hi Guys,

Im in the process of building a complete 3 inch turboback exhaust system,
Does this mean that if I ditch the Cats my exhaust fumes a gonna smell like rotten eggs??

Marlon

No you won't have this problem, it's the cat which causes the smell.

 

[senseikrang1]

From Winkipedia...Google is your friend
I highly doubt a bad O2 sensor is the cause of your problem...could be a contributor though. Especially is it is causing a lean AFR.

Thanks for the help. The only other mechanicle problems I can think of rite now is that there are a few oil leaks by the cam covers and as well the gasket behind the water outlet housing is dripping oil onto the exhaust manifold heat insulator....and its burning off

 

[jdub]

No you won't have this problem, it's the cat which causes the smell.

^^^ Sulfur is the likely culprit...the rotten egg smell is due to the CAT producing Hydrogen Sulfide

 

[marlonvip]

No you won't have this problem, it's the cat which causes the smell.

Thank you

LOAD OF MY MIND:icon_bigg

 

[monkeymantn]

Depending on where you live (i.e. emissions testing laws), you could do one of four things. 1) Replace the cats (expensive); 2) buy a used exhaust from a junk yard; 3) replace the cats with glass packs (these can be low toned and not obnoxious); or 4) straight-pipe the exhaust. I suppose it depends on your local laws, budget, and how stock you want to keep the car. Good luck.

 

[Poodles]

can't buy a used cat from a junk yard

 

[monkeymantn]

can't buy a used cat from a junk yard

True, you can't buy just the cat...But, you can buy the complete exhaust most of the time. I've done it for other vehicles for less than $100.

 

[monkeymantn]

True, you can't buy just the cat...But, you can buy the complete exhaust most of the time. I've done it for other vehicles for less than $100.

By exhaust, I mean the complete exhaust system (i.e. from the manifold back).