Ammonia smell on 2014 - not sulfide

[dekeman]

There's a few non-concluding threads in the 4th gen section on this, and some in some Jeep forums, but none that I found that can definitively explain whether this is normal or not - I'm guessing it is, but want to know for sure and what might be the cause.

After a few seconds at startup in the cold in a 2014 Limited, there can be (not always) a distinct smell of ammonia from the exhaust. (I helped build an ammonia plant when I was in my teens, I know what ammonia smells like - almost like cat pee mixed with Windex.) It's quite strong, too, if you're standing near the exhaust, say loading snowboards into the cargo area, etc.

It is NOT hydrogen sulfide (rotten eggs), which commonly can result from the exhaust after hard acceleration and is deemed normal, hence the side-pipe exhaust mod some have done.

I suspect this ammonia smell has more to do with the grade of gasoline and the exhaust gases through the catalytic converter, but was hoping some more scientific minds might weigh in. Some in the 4th-Gen section even said there might have been a TSB on this.

Google searches turn up lots of others reporting this in everything from BMWs to Kias, but most of the forum replies are useless banter. I'm going to try some Shell Ultra 94 Octane to see if it makes a difference.

 

[1engineer]

Hey [MENTION=48776]dekeman[/MENTION],
I have noticed it as well but I think it is from a different source, at least for me. My rear window washer fluid is what I have deduced. The rear washer fluid will run down the tailgate and drip over the bumper and on to the tailpipe. I have no ammonia odor if I have not used the rear washer in awhile such as in the summer.

 

[dekeman]

Thanks Greg. Good suggestion, but it's definitely from the exhaust itself, does it most mornings. I even smelled it on the 2014 Infiniti QX60 Hybrid I drove recently, making me think it's the fuel and the combination of brand new cats and air pumps. I'm also asking Toyota if they can explain.

 

[mace.]

I found this on FJC forum.


Ammonia smell? - Page 3 - Toyota FJ Cruiser Forum

 

[BigredTEX]

One thing to consider is the chemical formula of ammonia, NH3. Nitrogen is the most common gas in our atmosphere and hydrogen is in the gasoline (hydrocarbon). It is very possible that the internal combustion process is generating some ammonia on cold start prior to the catalytic converters lighting up. Once up to temperature the catalysts start doing their job and you see primarily CO2 and H2O.

Edit: I just read the FJ Forum post provided by mace and it says the same thing. I amaze myself that I can remember some chemistry from college, which was a long time ago.

 

[dekeman]

Absolutely brilliant. Awesome reply Mace.
Here's the summation for the FJ post:

Toyota uses a Three Way Catalytic (TWC) converter. This style (not a toyota problem) has created a new problem for emissions that was [not prevalent in] the previous Two Way Cat Converter. These new Cats combined with improved low sulfur gasoline in certain conditions have been shown to produce Ammonia from atmospheric NO, NO2, NO3 entering the Cat Converter.

I'm guessing a switch to higher grade of fuel might reduce the smell — er, the ammonia, which also happens to be a cause of haze. And as the FJ member pointed out...."the unintended side effect through EPA emissions control is to have more smog."

Apparently a new Cat system is in the works. I'll report back after refuelling with 94 octane.

 

[philsey]

[MENTION=48776]dekeman[/MENTION] You dog, you're testing that 4R with the 1VD-FTV aren't you?

 

[dekeman]

[MENTION=48776]dekeman[/MENTION] You dog, you're testing that 4R with the 1VD-FTV aren't you?

Could you imagine? My dream come true.
No, it's got something else avant garde....

 

[bouncer07]

Instead of opening a different thread, I have a heavy foot and the smell comes with a low grade unleaded gasoline I put in. I've put BP 93 rated premium and stepped on it and it does not have the smell. Once I switch over to the lower grade, the smell will come back and burn whatever left in the cat on hard acceleration. The 4th generation v8 seems to have this problem, do they have that 3 way cat as well? Seems that this is normal but no one really have detected the root cause. Still going by assumptions, the cat and gasoline can play a major role because Toyota really advised us to use Premium on this engine but North America gave us the option to use the lower grade gasoline for refuel. Does the engine pings at lower grade gasoline? Anyone upgraded their cats?