Why add SCR and the Cheat

Early in the development of the Lean Trap system, however, it became apparent
to Volkswagen’s engineers that activating the Lean Trap and EGR as frequently as necessary to
bring NOx emissions within legal limits would produce too much soot for the Soot Filter. The
Soot Filter would in turn clog and break within just 50,000 miles of operation – far sooner than
the initially 120,000- and later 150,000-mile – Full Useful Life, U.S. durability standard
Volkswagen was required to meet.

Click to expand...

to comply with more stringent U.S. NOx limits and an EPA rule that tied urea tank
refills to the manufacturer’s service intervals, Audi’s 3.0 liter vehicles in the United States would
require larger urea tanks than their European counterparts.

Click to expand...

Some competitors, for example, had
service intervals as low as 7,500 or even 5,000 miles; Volkswagen and Audi, however, chose to
maintain a 10,000-mile service interval.

Click to expand...

In addition to the EGR defeat device implemented in the Generation 1s, the 3.0Ls
also featured a urea-dosing defeat device.

Click to expand...

In 2009, Volkswagen turned its attention to the planned roll-out in the U.S. of the
MY 2012 Generation 2 Selective Catalytic Reduction-equipped Passat, a model heavier than its
Generation 1 predecessors and therefore unsuitable for a Lean Trap emissions control system.
In designing an SCR-equipped emissions system for the Passat, however, Volkswagen’s
engineers now faced the same quandary their Audi colleagues had confronted – insufficient
space in the vehicle chassis to incorporate urea tanks large enough to meet the 10,000-mile refill
interval to which they certified the Generation 2s.

Click to expand...

In real-world conditions, the Generation 2s sold in this country exceeded lawful NOx
emissions levels by some five to twenty times

Click to expand...

compu_85 said:

So it was a matter of certification, not just convenience that the tank went over 10k miles?

Click to expand...

roni024 said:

The NY lawsuit is a must read. The more I read, the more it seems VW sees us as rubes that can be easily fooled. That will definitely weigh in on how I decide to proceed with a fix/buyback.
https://ag.ny.gov/sites/default/files/new_york_vw_complaint_7.19.pdf
Start reading on page 41 (p.45 of the PDF) about the sham recall.

Click to expand...

171. At that September 3, 2015 meeting, Volkswagen admitted for the first time that the Generation 2 ECUs had two calibrations: one for real world driving (Calibration 1) and one for testing (Calibration 2).

Volkswagen disclosed that in Calibration 1, the urea dosing, EGR and the Rail Pressure were lower. In Calibration 2, Volkswagen disclosed that the urea dosing, the EGR and the Rail Pressure were higher.

Click to expand...

jims2321 said:

Apparently. More of a marketing gimmick. Look we only require service every 10K, everyone else is half our interval, we are superior. The NY State attorney is right on one thing, VW is arrogant to an extreme.

Click to expand...