Horrible ammonia smell from exhaust

[Dry-fly]

I’m wondering if my cat is bad... if I drive with the rear window down any at all I get a horrendous ammonia smell sucked inside. It’s a 2007 V8 4Runner. About 183k on the odo. Ideas?
Thanks!

 

[Jayson44]

I had this exact same thing happen the other day in my 05. thought it was from a smell outside. :/

J.

 

[Dry-fly]

Sorry guys, I found some old responses to this issue. Seems it’s a common thing.

 

[Bossman]

rotten egg smell...

Sulfur smell when accelerating hard

Rotten Egg/Sulfur Smell?

TSB on sulfur smell for V8 03-04 4 Runners

TSB recall Sulfur smell is nauseating but only comes intermittently Need tips

Rotten egg smell. Does it go away???

 

[Dry-fly]

Thank you for the links ^^

 

[chaz]

pretty sure the manual says not to drive with rear window down but having the exhaust rerouted out the side have helped some.

 

[JVC8790]

pretty sure the manual says not to drive with rear window down but having the exhaust rerouted out the side have helped some.

I think it did too, I have the TRD Dual Exhaust with dumps behind the rear wheels out on an angle, I only get this smell now when driving uphill. Flat ground or downhill doesn't smell.

 

[Inv4drZm]

Do you guys have any of the front windows open too? Or just the rear?

 

[Jayson44]

Do you guys have any of the front windows open too? Or just the rear?

I smelled it when I had the sunroof open and the rear window down. super strong, like someone spilled a bottle of ammonia in my truck.

J.

 

[pahaf91]

I read that its a common issue with our 4Runners. Even when when they just came out from the factory, people were noting it.

What Toyota said was to try different fuel stations.

But for me, it was really bad when i bought my 2006 v6 with 192k miles. Replaced my cats, and it is only present now when the car is going uphill under load.

 

[Seymore Butts]

You guys realize that ammonia does not smell like sulfur, right?

Sulfur smells like old eggs.

Ammonia smells like unscented full strength Windex.

They're not the same.

 

[Jayson44]

You guys realize that ammonia does not smell like sulfur, right?

Sulfur smells like old eggs.

Ammonia smells like unscented full strength Windex.

They're not the same.

mine did not smell like sulfur or eggs. it smelled (I've only smelt it once) like someone spilled a bottle of ammonia on my seat. stung my nose, made me cough...ammonia.

J.

 

[gaber6]

I keep my front windows open if I drive with my rear window down. Sulfer smell on uphills does come in a little though. V6 170k miles.

 

[trey99ek]

I'm pretty sure mines smelled that way since I bought it in 08.

Sent from my SM-G960U1 using Tapatalk

 

[Jayson44]

interesting...today I smelled both the sulfur/eggs smell while driving somewhat normally, and the stinging ammonia smell when accelerating. so yeah, they're two distinctly different smells.

consensus seems that the sulfur/eggs is "normal" or at least to be expected. but what about the ammonia? cats going bad?

J.

 

[AuSeeker]

From all I have read about ammonia exhaust smells, there's no definitive answer, but the answers I have seen vary from a bad connection at some point in the exhaust allowing air to enter the system where it shouldn't be, bad Cat/s, or either bad or an additive in the gas.

Now if this was a diesel there are other possible causes but they don't apply in this case.

I would start with checking for any loose connections, bad gaskets or holes in the exhaust, if all's OK there then proceed and change where you get your gas, go with a better/name brand gas station, if you still have the issue the only thing left is the Cats.

If you find any issue in the steps above. fix them one at a time but make sure you allow a time period between each steps to see if that was what's causing the issue, don't go crazy and do all at once otherwise you will not be sure you have isolated the cause.