Anyone experienced increased NO2 emissions on modern tractors with DPF?

[Snobdds]

NOx is produced in the combustion chamber, not so much the exhaust, the EGR is there to reduce the NOx by reducing combustion chamber temps via introducing the spent exhaust into the intake.

It helps, but the EGR does not operate at all times during operation.

The SCR is what operates all the time during operation.

 

[RBsingl]

Does your tractor also use DEF? Most Tier IV compliant will and these use a SCR (selective catalytic reduction) system that injects DEF (diesel exhaust fluid which is a specific concentration of ammonia). In the SCR, the DEF reacts with the exhaust converting the various NOX products. There is a definite smell to the exhaust from a DEF equipped system and if there is a problem with it, then it can put excessive ammonia into the catalyst resulting in significant ammonia gas in the exhaust which is an extreme irritant.

If not for the DEF/SCR system, diesel fuel efficiency would be even lower with Tier IV engines because it allows higher combustion temperature/pressure which is what creates NOX and then cleans it up via the catalytic reaction. Think of it as offsetting some of the power/efficiency loss that the DPF creates as they work together to meet Tier IV.

Rodger

 

[5030]

Way too complex for me. I have none of those issues and I'd never burn my lips on a hot exhaust pipe either.

I do know one thing for certain and that is an over dosing system stinks bad. Smells sort of like hot cat pee..

 

[5030]

Does your tractor also use DEF? Most Tier IV compliant will and these use a SCR (selective catalytic reduction) system that injects DEF (diesel exhaust fluid which is a specific concentration of ammonia). In the SCR, the DEF reacts with the exhaust converting the various NOX products. There is a definite smell to the exhaust from a DEF equipped system and if there is a problem with it, then it can put excessive ammonia into the catalyst resulting in significant ammonia gas in the exhaust which is an extreme irritant.

If not for the DEF/SCR system, diesel fuel efficiency would be even lower with Tier IV engines because it allows higher combustion temperature/pressure which is what creates NOX and then cleans it up via the catalytic reaction. Think of it as offsetting some of the power/efficiency loss that the DPF creates as they work together to meet Tier IV.

Rodger

Actually DEF is nothing but Urea in solution and deionized water. Makes great fertilizer for hay. I buy out of date DEF and fertilize my hayfields with it. Much ceaper than using granulated urea or 28% liquid.

 

[RBsingl]

Actually DEF is nothing but Urea in solution and deionized water. Makes great fertilizer for hay. I buy out of date DEF and fertilize my hayfields with it. Much ceaper than using granulated urea or 28% liquid.

Great way to use an otherwise "spoiled" product!!!

Rodger

 

[5030]

Great way to use an otherwise "spoiled" product!!!

Rodger

Absolutely it is and I like buying 'out of date' or frozen and thawed DEF in 350 gallon totes. Just picked up 700 gallons in 2 IBC's for 400 bucks from a truck dealership. Not sure why it has an expiration date as it don't go bad, even if frozen. Still stinks like cat pee...lol

I always return the totes as a courtesy.

They are heavy full, all my M9000 can do to lift one up.

 

[LouNY]

I have noticed a very rank and difficult fumes from diesels with def systems, both trucks and tractors when trying to work on them or hook up trailers or implements. Even in just 3 sided sheds. Much worse then the older so called "dirty" diesels.

 

[5030]

I have noticed a very rank and difficult fumes from diesels with def systems, both trucks and tractors when trying to work on them or hook up trailers or implements. Even in just 3 sided sheds. Much worse then the older so called "dirty" diesels.

Lou.. A DEF system that is over dosing urea will melt your eyeballs in a minute. Nothing stinks worse. I'll take my dirty diesels anytime compared to a clean diesel spewing urea fumes.

 

[5030]

The issue with DEF injection systems is just that, metering the injection rate properly and doing it when it's cold out or hot out. Prior to retirement, the dealership I worked at had a steady diet of failed DEF systems and they are not fixable, just replacable. Stuff stinks.

 

[RBsingl]

Absolutely it is and I like buying 'out of date' or frozen and thawed DEF in 350 gallon totes. Just picked up 700 gallons in 2 IBC's for 400 bucks from a truck dealership. Not sure why it has an expiration date as it don't go bad, even if frozen. Still stinks like cat pee...lol

I always return the totes as a courtesy.

They are heavy full, all my M9000 can do to lift one up.

Fortunately I don't need that quantity of DEF for my pickup so I either add at a station or buy Kleen DEF at Farm and Fleet in the 2.5 gallon containers when they are on sale.

Freezing won't hurt it but long storage in hot temperature (including sitting in the tank of a pickup that is only driven a few hundred miles a year) will "age" it. DEF systems are very finicky and the dosing rate is coarsely controlled by the fueling rate and fine tuned by the downstream "sniffer" but there is only a small amount of latitude in fine tuning (probably thanks to the EPA) so if the NOX isn't reduced sufficiently at maximum positive bias it declares an error. And faults with the DEF system under EPA only allow extremely short term operation before the engine output is reduced to the point that it will barely pull itself onto a trailer.

I remember when I ordered my 2018 GMC 2500HD, I always use GM's fleet order guides which have much more detail than what the dealer provides and I use it for configuring the vehicle. The truck chassis ordered for ambulance or fire service still has full emissions but at the time a DEF fault caused the vehicle with emergency use certification to go into limp mode at 50,000 miles following a DEF/SCR system fault; I could live with that limitation if only that option was available on regular consumer orders

Rodger