Isn't it only the smaller VW diesels that use the NOx absorber as opposed to SCR? I believe (at least) the Touareg uses SCR.
Quote:
Originally Posted by Old Tele man
I base my original comment on the fact that when I walked through our local VW dealership and one of the diesel engined vehicles was started-up by the salesman for another customer, there was an immediate "...latrine..." (piss) odor in the air.
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What's the difference between this and any other engine sold right now? Every engine, gas or diesel, smells like something bad when they fire up cold.
I am around SCR engines all day. Under normal circumstances, I have never smelled ammonia by being around them, unless someone was filling the DEF tank. When started cold, DEF isn't metered into the decomp tube until SCR catalyst inlet temp is pretty hot, like 400F or so. It takes a few minutes, as it is all post DPF, so the last thing to warm up. So smelling "piss" on a cold startup? Either something is seriously malfunctioning or the rank smell is merely the nastiness that goes on whenever a bunch of unburned fuel hits a cold catalyst, gas or diesel - aka: normal cold startup.
Not that I am an absolute advocate for SCR. I just think it is a decent solution compared to other solutions.