Possible reason for the defeat device

I've seen some posts that mentioned that the origin of the current defeat device was a noise reduction measure. (I forget the name: audible something, or something like that.)

As it turns out, to quiet the noise from ignition, they use "pilot injection", or inject some fuel before the main injection. (Overly simplified, but hopefully good enough.) The side effect is increased NOx.

Now, some people have commented on the fact that BMW and Mercedes have managed to pass emissions without the defeat device. Nobody has mentioned that the Chevy Cruze is able to boost an extra 10 hp for 10 seconds, but I think it is relevant.

I don't know how the Mercedes runs, but reading the reviews of the BMW, they mention that there are times, when under heavy acceleration, that it gets louder, or more dieselly.

I suspect that MB and BMW allow more noise, and are possibly better insulated to counter it. By using less of a pilot injection they would be louder, but emit less NOx.

In the case of the Cruze, I'll bet the car is normally 140 hp, and got a waiver from the EPA to allow additional pollution for only the 10 seconds. So, you can merge onto a crowded highway, or make that two-lane-road passing maneuver, but generally keep the emissions clean.

We know that VW has been fighting against the ghosts of the old GM diesel atrocities, and telling people that diesels are not loud, clanky, smoke blowing turds, but quiet, clean, and quick.
I can only imagine that they wanted to make sure the automotive press would be impressed by how quiet and not at all what they expected of a diesel these new cars were.
Most people also appreciate the quiet nature of these cars, and that was one of the selling points for some.

I am positing that this is the real reason VW used the defeat devices. If so, I am not sure why they couldn't just allow it to be a little louder and pass.

Unfortunately, I doubt we will ever know why they did what they did.

Personally, I think "acoustic device" was a code word used to avoid committing the phrase "defeat device" to the email/voicemail/etc. records.

I agree with S2000, "acoustic device" was probably code for "defeat device", and it probably does actually quiet the engine some.

As to why, it's obvious, they concluded that the car wouldn't sell without it. Many possible reasons for that, maybe it would cost $5000 more, maybe it couldn't get fuel mileage as good as gassers, maybe it'd have lackluster acceleration, maybe the engine eats itself rapidly. Whatever the reason, we'll find out once fixed vehicles are put back on the road and we find out how their performance had changed (or not changed).

As I understand it, burning the air to make NOx is related more to combustion temperature than anything else. I'm not sure if pilot-injection makes that much difference.

Heck, even Cummins went to pilot injection to control noise . . . it is a real, deployed, solution in a lot of diesels, so how about we loosen the tinfoil hats on the conspiracy theories? And to that end, I bought a diesel and have no problem whatsoever if it actually sounds like one . . .

tadawson said:

Heck, even Cummins went to pilot injection to control noise . . . it is a real, deployed, solution in a lot of diesels, so how about we loosen the tinfoil hats..?

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+1 The undisclosed defeat needed to piggy back on some kind of code. This was it, and it wasn't entirely made up no matter how deceptive the defeat. It might have been the Fortune article, but well known that VW was doing all kinds of things to quiet diesel down and make it more efficient. Understanding that a rich mixture fed to an LNT cat is what takes NOx down, all those gains would have to have been "washed" away. So, I understand the engineers frustration. Multiple injections per ignition were a means to lean the mix, quiet it down, and get better mpg. Because of less unburned fuel reaching the LNT, it was ineffective as a result.

GetMore said:

I've seen some posts that mentioned that the origin of the current defeat device was a noise reduction measure. (I forget the name: audible something, or something like that.)
As it turns out, to quiet the noise from ignition, they use "pilot injection", or inject some fuel before the main injection. (Overly simplified, but hopefully good enough.) The side effect is increased NOx.
Now, some people have commented on the fact that BMW and Mercedes have managed to pass emissions without the defeat device. Nobody has mentioned that the Chevy Cruze is able to boost an extra 10 hp for 10 seconds, but I think it is relevant.
I don't know how the Mercedes runs, but reading the reviews of the BMW, they mention that there are times, when under heavy acceleration, that it gets louder, or more dieselly.
I suspect that MB and BMW allow more noise, and are possibly better insulated to counter it. By using less of a pilot injection they would be louder, but emit less NOx.
In the case of the Cruze, I'll bet the car is normally 140 hp, and got a waiver from the EPA to allow additional pollution for only the 10 seconds. So, you can merge onto a crowded highway, or make that two-lane-road passing maneuver, but generally keep the emissions clean.
We know that VW has been fighting against the ghosts of the old GM diesel atrocities, and telling people that diesels are not loud, clanky, smoke blowing turds, but quiet, clean, and quick.
I can only imagine that they wanted to make sure the automotive press would be impressed by how quiet and not at all what they expected of a diesel these new cars were.
Most people also appreciate the quiet nature of these cars, and that was one of the selling points for some.
I am positing that this is the real reason VW used the defeat devices. If so, I am not sure why they couldn't just allow it to be a little louder and pass.
Unfortunately, I doubt we will ever know why they did what they did.

Click to expand...

Pilot injection was only generation 1 of VW's defeat device. There are six generations of defeat devices. Gen 1 was put in place in 1999.

If this stopped with Gen 1 VW wouldn't be in the mess they are in now.

Read up on the history of VW defeat devices here:

https://ag.ny.gov/sites/default/files/new_york_vw_complaint_7.19.pdf

VW took this trick right out of the over-the-road diesel engine playbook. This had been done years earlier by the big diesel companies.

GetMore said:

I've seen some posts that mentioned that the origin of the current defeat device was a noise reduction measure. (I forget the name: audible something, or something like that.)
As it turns out, to quiet the noise from ignition, they use "pilot injection", or inject some fuel before the main injection. (Overly simplified, but hopefully good enough.) The side effect is increased NOx.
Now, some people have commented on the fact that BMW and Mercedes have managed to pass emissions without the defeat device. Nobody has mentioned that the Chevy Cruze is able to boost an extra 10 hp for 10 seconds, but I think it is relevant.
I don't know how the Mercedes runs, but reading the reviews of the BMW, they mention that there are times, when under heavy acceleration, that it gets louder, or more dieselly.
I suspect that MB and BMW allow more noise, and are possibly better insulated to counter it. By using less of a pilot injection they would be louder, but emit less NOx.
In the case of the Cruze, I'll bet the car is normally 140 hp, and got a waiver from the EPA to allow additional pollution for only the 10 seconds. So, you can merge onto a crowded highway, or make that two-lane-road passing maneuver, but generally keep the emissions clean.
We know that VW has been fighting against the ghosts of the old GM diesel atrocities, and telling people that diesels are not loud, clanky, smoke blowing turds, but quiet, clean, and quick.
I can only imagine that they wanted to make sure the automotive press would be impressed by how quiet and not at all what they expected of a diesel these new cars were.
Most people also appreciate the quiet nature of these cars, and that was one of the selling points for some.
I am positing that this is the real reason VW used the defeat devices. If so, I am not sure why they couldn't just allow it to be a little louder and pass.
Unfortunately, I doubt we will ever know why they did what they did.

Click to expand...

Greed. Period.

They couldn't sell the cars without the defeat device and they mistakenly calculated that the benefit (selling the cars) outweighed the potential cost (fines only...they didn't even begin to grasp the civil implications) if they were caught.

If anything...this whole thing is just a big exercise in greed and arrogance. Like most white collar criminals...they did what they did because: 1. They thought they could get away with it, and 2. If they got caught, they thought that the potential gain would far outweigh the possible penalties. So back to that one word..."greed."

These threads have a way of turning from a rationalization of what VW did to justification. And that's pointless. They admitted to what they did last September.

Rico567 said:

These threads have a way of turning from a rationalization of what VW did to justification. And that's pointless. They admitted to what they did last September.

Click to expand...

Yep, they did it because they could. They did it because the single stage after treatment (just Nox trap/DPF) alone, without a secondary DEF converter was not quite good enough, while getting the MPG and performance. They could have made it compliant.

However to be compliant it might have had to scrap existing plans after
they found the problem so the tweaked the software. Retooling would have
been another year or more delay and billions. In retrospect that would
have been best maybe.

Even if they would have had a plan from the get go it would have cost
more, weighed more and not been as efficient. They made a choice and
the bull about some rouge engineer doing it on their own is of course bull.

When and who made the decisions and why would be of interest to
me in understanding this business and engineering failure. At this
point it is academic and we may never know why, who and how it
happened. As was said above, it happened and they admit they did it.

Why did they do it? At least on Gen 1 cars, i believe to keep the engine pollution control devices "full on, all the time" would result in those devices failing, the need for more frequent scheduled maintenance, and poorer perceived engine performance.

To reduce emissions warranty claims. And ,gen 1, so they did not have to license tech from MB