Ammonia smell from exhaust - 2.5L

[WatchYourSix]

Didn't see any other posts about this. Over the past few months my wife and I noticed a smell of ammonia in the driveway periodically. We even had the gas company come and check the house. Finally figured out it was my wife's Maverick ('22 Hybrid XLT). We have only noticed the smell at idle after remote start. I will have her check if she smells it at idle upon returning home from a drive. Saw a few posts on other forums such as this one. An article from vehiclefreak.com indicates it could be a fuel leak, faulty cat or a few other possibilities. No smoke, visible leaks underneath or in the engine bay, or from the exhaust when running. Anyone else experience this?

Sponsored

 

[fossil]

similar to rotten eggs? Cat-converter exhaust issue?

 

[WatchYourSix]

similar to rotten eggs? Cat-converter exhaust issue?

No egg smell. More like nail polish remover or ammonia.

 

[Bigbill27]

No egg smell. More like nail polish remover or ammonia.

Sounds like paint cooking.

 

[19mustang65]

I've noticed that too. It's a strong ammonia cat piss type smell. Only noticed during remote starts as well.

 

[WatchYourSix]

Sounds like paint cooking.

Smells more astringent than paint.

 

[WatchYourSix]

I've noticed that too. It's a strong ammonia cat piss type smell. Only noticed during remote starts as well.

Yep that's it. It obviously isn't limited to hybrids or the 2.5L as members of the Escape forums with several different engine types have experienced it, including the 2.0 EB.

 

[Darnon]

The air/fuel/timing profiles during warmup are different to help get the engine and catalytic converters to their operating range. And the catalytic converter being cold also changes the emissions (both scentless and aromatic) in that period.

 

[RedRider]

Bad fuel?

 

[WatchYourSix]

The air/fuel/timing profiles during warmup are different to help get the engine and catalytic converters to their operating range. And the catalytic converter being cold also changes the emissions (both scentless and aromatic) in that period.

So this smell is considered normal? I realize catalytic converters run much hotter than outside ambient temps but I've never experienced this on other vehicles I've owned.

Bad fuel?

Aside from a few fill-ups on a road trip, we always use Costco 87 or 93, so Top Tier. 8,062 miles, mostly highway.

 

[Kingfish]

Weird. We smelled ammonia the other day right after starting the truck. It only lasted a minute or two so I thought maybe it was something in our neighborhood.

 

[GPSMan]

Almost certainly you are smelling gasoline. Unburned gasoline or partially burned gasoline.

On a cold engine extra fuel is intentionally injected. Believe it or not, the emissions control engineers WANT unburned fuel to make it to a cold catalytic converter. Then, at a point, the fuel in the converter will reach auto ignition temperature and "light off". This will create instant heat, 40° per second temperature rise, heat the converter needs to convert harmful emissions to less harmful by-products.

A Catalytic converter is useless below 300°C. Most efficient at 400-800°C, and can routinely reach 1000°C under high engine load conditions.

At idle; during "remote starts", your catalytic converter is warming up slowly, you are smelling unburned fuel, and you are polluting more. You are smelling the pollution from a rich fuel mixture and an under temperature catalytic converter.

So I never really thought about it until now, but our Mavericks have an "afterburner"! One more tie in to the movies!

 

[Ford Motor Company]

Didn't see any other posts about this. Over the past few months my wife and I noticed a smell of ammonia in the driveway periodically. We even had the gas company come and check the house. Finally figured out it was my wife's Maverick ('22 Hybrid XLT). We have only noticed the smell at idle after remote start. I will have her check if she smells it at idle upon returning home from a drive. Saw a few posts on other forums such as this one. An article from vehiclefreak.com indicates it could be a fuel leak, faulty cat or a few other possibilities. No smoke, visible leaks underneath or in the engine bay, or from the exhaust when running. Anyone else experience this?

Good morning! If you send over a DM with your VIN and Ford dealer info, I can look into your odor concerns on my end.

 

[ychuck46]

Aside from a few fill-ups on a road trip, we always use Costco 87 or 93, so Top Tier. 8,062 miles, mostly highway.

Not criticizing your post, it's just that I get a kick out of people thinking one brand of gas, or one purveyor of gas, is better than the others. Have you ever seen the unmarked tanker truck filling up the tanks at your Costco? After he is done there he will be stopping at Walmart or Kroger's to fill their tanks as well. No station gets the same deliveries from the same top tier delivery company every time.

 

[WatchYourSix]

Not criticizing your post, it's just that I get a kick out of people thinking one brand of gas, or one purveyor of gas, is better than the others. Have you ever seen the unmarked tanker truck filling up the tanks at your Costco? After he is done there he will be stopping at Walmart or Kroger's to fill their tanks as well. No station gets the same deliveries from the same top tier delivery company every time.

Fair enough, but this has persisted through many fill-ups. Seems unlikely every batch of gas was "bad".

Sponsored