'99 4Runner 3.4L smells like rotten eggs

[CZ Eddie]

For as long as I can remember, my 130K mile '99 4Runner Limited exhaust has smelled obscenely like rotten eggs.

I've done the usual things like clean the fuel and oil with SeaFoam. New spark plugs. PCV valve. Clean the throttle body & sensor. New oil & filter.

The Sea Foam treatment kinda, sort of seemed to help a little. Could just be my imagination though.

Any ideas on what I can do? It's pretty embarrassing to be idling in my car and people around me hold their noses. Okay it's not that bad, but it is close.

I just hooked up an ODB II scanner to the Torque Pro Android app. So I can get a/f mixtures and other info if it helps.

 

[RunninOnBlue]

Do you usually fill up at the same gas station? It's probably unrelated...but Arco Am/Pm stations around here have a reputation of selling higher sulfur gasoline.

But it is most likely your catalytic converter or a rich air/fuel ratio. Have the O2 sensors been replaced?

A cheap option would be to run some techron or other fuel injector cleaner through it. See if that helps.

 

[FancyPantsMcGee]

do a search on the forum for "egg smell", I know I've seen this come up in the past.

 

[Ruiner]

For as long as I can remember, my 130K mile '99 4Runner Limited exhaust has smelled obscenely like rotten eggs.

I've done the usual things like clean the fuel and oil with SeaFoam. New spark plugs. PCV valve. Clean the throttle body & sensor. New oil & filter.

The Sea Foam treatment kinda, sort of seemed to help a little. Could just be my imagination though.

Any ideas on what I can do? It's pretty embarrassing to be idling in my car and people around me hold their noses. Okay it's not that bad, but it is close.

I just hooked up an ODB II scanner to the Torque Pro Android app. So I can get a/f mixtures and other info if it helps.

kinda sounds like a bad cat converter or an exhaust leak

 

[CZ Eddie]

Yeah, it has still the original cat on it. My searching reveals that the aftermarket cats SUCK and a replacement OG cat is $$$$.

That's why I used the SeaFoam. I read that it helps clean out the cat.
I also read that I can remove the cat and drop it into a bucket of soapy water for a few hours. I haven't done that yet though because one of the damn bolts is STUCK & my socket started rounding over the bolt corners. I need to take it to a muffler shop to have them loosen it up.

I don't "hear" any exhaust leaks though. No pinging sounds or anything.

 

[Ruiner]

Yeah, it has still the original cat on it. My searching reveals that the aftermarket cats SUCK and a replacement OG cat is $$$$.

That's why I used the SeaFoam. I read that it helps clean out the cat.
I also read that I can remove the cat and drop it into a bucket of soapy water for a few hours. I haven't done that yet though because one of the damn bolts is STUCK & my socket started rounding over the bolt corners. I need to take it to a muffler shop to have them loosen it up.

I don't "hear" any exhaust leaks though. No pinging sounds or anything.

how old is your battery?

 

[Ruiner]

i put an aftermarket cat on my civic when my old one cracked, never had any issues with it

 

[CZ Eddie]

how old is your battery?

Only a year old, but I've been having trouble with it. Am planning to replace it & the alternator in a month. It dies pretty quickly.

i put an aftermarket cat on my civic when my old one cracked, never had any issues with it

The 4Runner cat is apparently pretty special. Very mixed results from aftermarket cats are found all over the forums.

 

[Skidmarcx]

Could be bad battery... If you're certain it's coming from the tailpipe I suspect bad catalyst

 

[Ruiner]

Only a year old, but I've been having trouble with it. Am planning to replace it & the alternator in a month. It dies pretty quickly.



The 4Runner cat is apparently pretty special. Very mixed results from aftermarket cats are found all over the forums.

a bad battery can give off a rotten egg smell, you may want to call the local salvage yards and see if you can find a used one. Funny thing is ive run no cat before and it doesnt smell like that, like raw fuel yeah, but not the sulfer smell.

 

[CZ Eddie]

Thanks guys.
That's very interesting. I never knew that about batteries.
Have some allergies right now so it's hard to tell where the smell comes from ATM, but I'll look at the battery also now!

 

[kenyansagi]

Mine smelled like that too when I bought it but the used car dealer gave me a new aftermarket cat which has been great so far and also met the aircare standard here

 

[TheDurk]

a bad battery can give off a rotten egg smell, you may want to call the local salvage yards and see if you can find a used one. Funny thing is ive run no cat before and it doesnt smell like that, like raw fuel yeah, but not the sulfer smell.

There's sulfur in fuel additives; your engine isn't burning it completely and your catalytic converter is storing it and then releasing it as hydrogen sulfide when you add load to the engine and force more air through.

No cat will indeed smell like fuel.

If left doing this for long the cat will die.

 

[CZ Eddie]

Hah, my 4runner finally gave me a check-engine-light (CEL)! I used the bluetooth ADBII and Torque Pro app to check the code. It was P0420. Some digging around shows that is either a bad cat or a bad rear 02 sensor.

I've replaced the front 02 with a Denso about a year ago. I'll now replace the rear 02. And start researching replacement cats.

$55 shipped for the rear Denso 02. Best price I found on the net. Amazon Prime was $67.
http://www.ebay.com/itm/300792423211?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

And I found that Magnaflow now has California emissions/02 sensor compatible catalytic converters. Kinda expensive at ~$300 the front & $250 for the rear bolt-ons, but they're going into my extended wishlist:
http://www.magnaflow.com/02catalytic_converters/02product/02california.asp

 

[CZ Eddie]

I replaced the rear 02 sensor and ran a fuel system cleaner.
Now it doesn't smell like rotten eggs unless it's been idling for several minutes, then it starts smelling that way a little bit.

Haven't been able to afford new cats yet.

 

[madbomber08]

There's sulfur in fuel additives; your engine isn't burning it completely and your catalytic converter is storing it and then releasing it as hydrogen sulfide when you add load to the engine and force more air through.

No cat will indeed smell like fuel.

If left doing this for long the cat will die.

I'm confused at what you're saying. Since I've had my 4runner, whenever I put extra load on the engine, I get the rotten egg smell. I've never looked into it because I rarely push it to the limits of the rpm range. I guess I'm just curious if it's the battery or the catalytic converter. (The battery is from 2007)

 

[TheDurk]

I'm confused at what you're saying. Since I've had my 4runner, whenever I put extra load on the engine, I get the rotten egg smell. I've never looked into it because I rarely push it to the limits of the rpm range. I guess I'm just curious if it's the battery or the catalytic converter. (The battery is from 2007)

If the battery is making the smell you have a real problem. That happens when the battery is seriously overcharged and it is boiling off the electrolyte. Electrolyte is sulfuric acid and water. Normally only water evaporates, and not from a sealed battery. If sulfur is being boiled off, the water is largely gone, which means an explosive mix of hydrogen and oxygen has been filling your engine bay. A battery explosion is seriously nasty. Check the electrolyte level in your battery. If it's full, and charging voltage does not exceed 14.5 volts, that's probably not it.

Battery Explosion Short Clip - YouTube

It's unlikely you can have this situation persist for a long time. If it doesn't explode, the battery will fail. The cat issue, caused by a rich fuel mixture allowing unburned fuel to reach the cat, on the other hand, can persist for quite some time if the mix is only slightly rich. Eventually, the system will set off a CEL and fail any sniff test. Given enough time, either excess heat will destroy the ceramic substrate or it will become plugged up and choke the engine out due to blockage of exhaust.

Either way, sulfur smell is not something to leave unresolved. New cats are expensive. You should be able to resolve which it is by looking and smelling the car when the hood is up and engine running. If battery is hissing and out gassing, don't bother getting close to it to smell it. SHUT IT DOWN and call a mechanic before it blows up in your face. Note: overcharging does not occur because the battery is old. It occurs because your voltage regulator in your alternator is not working right and not lowering output as cells charge.