The sweet smell of ULSD
 

The other week I had to yank my sons 1999 turbodiesel out of the snow so I used a tow rope attached to the rear of my 07 ML CDI.
As I was down on my knees attaching the rope I had my face right on the tailpape. I was really surprised how undiesel like the exhaust smell really was. It was almost a sweet smell.
I guess going from 500 ppm down to 15 ppm sulfer really cleaned thing up.
Wonder if the commen rail direct injection techniques help clean up the combustion too?

The short answer is "yes". The reason for common rail is better control over the injection event thru electronics and, of course, finer atomization. Common rail allows control over injection amount, timing, and pretty much all other injection variables as a response to feedback from the various sensors - not readily possible with mechanical injection. The computer also monitors and controls intake manifold pressure (boost), transmission shift points (with auto trans), EGR function, and pretty much everything else in the car. The aftertreatment system is there to just sort of clean up what's left.

Almost forgot - the ULSD is just required to keep the aftertreatment system alive. Sulfur will contaminate an aftertreatment system like lead will contaminate a catalyst on a gasoline-fueled engine. The improved exhaust aroma is just a side benefit, though a nice one.

Dan

Does your CDI have one of the new particulate filters on it? It probably does which is why it smells sweet and so un-diesel like. All the new fords are the same way.

Yes the CDI has the particulate filters. I guess all those factors add up to cleaner and more efficient engine operation
I recall back in the day the old oil burner diesels trailing a tail of black sooty smoke under heavy acceleration.
Is the " Italian Tune-up" unnecessary any more with the CDI's ?

dude99 is correct, it's the after treatment giving you the smell, not the ULSD. My '03 common rail Dodge with no emission controls still has the typical smell on ULSD.

Agreed. It's the cat.

My 87 smells like old school.

My 98 and 08s have that odd smell. At first I thought I had a bad batch of fuel until I started smelling other new Diesel vehicles and realizing that's how they all smell when they have post treatment.

The urea after treatment systems smell better than the DPF VW ones that do a burnoff regen, when those are doing the regen cycle they smell awful.

From what I have smelled from these newer Diesels is a Chlorine or Clorox smell. Like breathing poison.

And the city busses burning natural gas. yuk. :puke:

Charlie

Yes it is very much like chlorine gas. The gases created by the DPF actually ARE toxic and poisonous, so there's an ADDITIONAL catalyst to further treat it and make it non-dangerous if breathed by accident.

everyone just run high % biodiesel so the world can smell like french fries and popcorn thank youuuu

LOL
You should get your nasal passages checked.

One thing I've always taken note of is the unique smells of different engines. My Benz's, my old Powerstrokes, the different Cummins (we have 5.9 common rails and 6.7's at my work), and the Duramax. They all smell a bit different, with the biggest changes being in correlation to the technology they use.

Agree, they smell like bleach or chlorine. I have experienced this several times being behind my wife's 2013 Passat TDI. No issue unles she accelerates hard, then you smell a faint chlorine smell....