
How Much Power Does the Volkswagen TDI Lose in “Cheater” Mode? - danso
http://www.tflcar.com/2015/10/how-much-power-does-the-vw-tdi-lose-in-cheater-mode-video-report/
======
kalleboo
This test seems very poor. They didn't measure the NOx emissions so we don't
know if it really entered "cheater mode". According to a comment there, it was
probably trying to compensate for what it detected as the rear wheels spinning
and they need to turn off DSP. It doesn't sound like they really knew what
they were doing so I'm not sure I trust it.

~~~
Theodores
All of this testing can be seen as very poor, however, I would argue that we
are running the wrong tests. Let me explain...

Imagine you were developing a car. As part of the project you would need to
test, test, test and test the drivetrain and the engine. For your test data to
be relevant you would want a controlled environment, e.g. car on perfectly
flat road with no pot holes, turns or aerodynamic consideration. You could
then adjust the variables and check the results - power, torque, emissions,
noise level, oil use, fuel use, temperatures and so on.

In this development mode the test rig works pretty good. Figures can be
produced that are important for the engine/drivetrain development. Variables
can be changed and results measured. The figures - defeat device aside - are
actually true with the normal margins for statistical measurement (not every
engine will be 100% exactly the same even if it came off the same production
batch).

The problem - defeat device aside - is when regulatory bodies use this data
for what they need to know, i.e. real world performance. They accept data that
they know is not real world and accept it as 'fact'.

If we look at our own testing for building apps, websites and such like we
take a modular approach, testing our dev boxes with some type of 'seige' that
does not factor in real world internet connectivity and bandwidth, not to
mention how customers might use our products in the wild. We can even prove to
our clients that their site isn't slow, sharing our metrics with them. Yet, in
the real world things don't quite attain those metrics. Luckily nobody gets
harmed if our 'squirrel picture app for cats' app falls short.

So, it is the procedures that are wrong and our standards bodies that are
doing it wrong (by blindly accepting manufacturers' test data). We are lucky
that VW have been cheating as we now are having the conversation about the
testing methodology.

~~~
nl
_For your test data to be relevant you would want a controlled environment,
e.g. car on perfectly flat road with no pot holes, turns or aerodynamic
consideration. You could then adjust the variables and check the results -
power, torque, emissions, noise level, oil use, fuel use, temperatures and so
on._

That's not how cars are developed. There is some of this for sure, but even
"static" dyno tests involve varied workloads to simulate an urban environment.
The European Driving Cycle[1] is a fairly basic example of this.

[1]
[https://en.wikipedia.org/wiki/New_European_Driving_Cycle](https://en.wikipedia.org/wiki/New_European_Driving_Cycle)

------
acd
I have an idea for a different test method.

You take your cheating Volkswagen TDI without software fix to the local
dragstrip on a day with little wind and do a series of test runs, you document
your 1/4 mile time.

Then you send in your car for a fix to Volkswagen most likely a ECU software
update as that is cheapest fix.

You retest your car at the drag racing strip, record the same number of runs.

If the numbers between the test run differ much you can sue Volkswagen as the
car may have worse performance with the legal Nox emission software.

Here is a device that will let you test your car perfomance on normal roads.
[http://www.vboxmotorsport.co.uk/index.php/en/products/perfor...](http://www.vboxmotorsport.co.uk/index.php/en/products/performance-
meters/performancebox)

Disclaimer I own a car with the affected engine.

~~~
toast0
That's a better test method, but since the VW fix is not available, it's worth
trying something else. Although in this case, it seems the methodology is
suspect: traction control applied brakes may be the source of the lost
horsepower, and emissions weren't measured so there's no confirmation that the
enhanced emission control mode was enabled either.

------
mberning
The methodology here is highly suspect. First of all they are using an AWD
dyno which can be unlinked to test a FWD or RWD car. It is expected that the
car will dyno lower when driving the rear wheels as well as the front. Not
only does it have to turn the drums of the dyno but also the rear wheels,
tires, and brakes of the vehicle. Second, a key component of the cheat as
reported by the media is keying off of the presence of the OBDII
instrumentation. As far as I can tell they did not have any way of simulating
this condition.

~~~
kw71
Not all emissions tests are conducted with OBD2 link. In some relaxed regimes,
OBD2 interrogation is the only component of the emissions test, and the car
passes if the car determined there is no faults. I lived in a county with
emissions testing and the OBD2 link was used as a pre-test before the dyno
run, and to feed the VIN number into the state's computer to provide some
assurance about the identity of the car being tested.

Some vehicles, like my Toyota, indeed behave slightly differently if there is
a diagnosis computer connected. I don't know if this applies to the OBD2 link
as well as the toyota-specific connector under the hood, but it's pointed out
in the factory shop manual. At any rate this knowledge has prevented me from
trying the "scangauge" type of data collection device.

------
po
> The acceptable particulate level in Colorado emissions testing is 35%
> opacity. That means the smoke and particulates that are coming out of the
> exhaust pipe can block up to 35% of light and pass the test. This is a lot
> of smoke.

This is the most shocking part of this... can you really pass with that much
smoke coming out the tailpipe? That's absurd and I find it hard to believe.
What's even the point of testing based on those regulations?

~~~
Asbostos
The 35% is a meaningless number without more details. It's not shocking at all
if a 1km column of smoke blocks more than 35% of the light passing along it.
So we need to know more about the test to decide if it's shocking or not -
specifically the distance the light travels through the sample.

Integration time is also important. Short bursts of dense smoke can be equally
polluting as a continuous stream of light smoke.

------
sandworm101
While not conclusive, I give these guys credit for replicating a behavior
fitting the "cheater" profile. But I am surprised that not spinning up the
rear tires triggered that behavior.

The loss in power measured here will be very noticeable to diesel owners.
Diesels have narrow power bands. You don't spend much driving time anywhere
near the top hp zone. The torque curves are what matters. A 10% loss means you
will probably have to rev up another 10%, say 3300 rather than 3000, to get at
the same power. While a professional reviewer stepping into a car for the
first time might not notice, the guy taking his personal vehicle in sure will.
VW owners will not be happy if the coming fix reduces torque by this much.

I suspect this "cheat" is done by enriching the mixture a little to lower the
temp and reduce NOx. Conversely, VW might have been running things too lean
under normal operation. A lean (oxygen-rich) mixture burns hotter, resulting
in more power and efficiency but much of that unburnt O2 ends up combining
with N2 to form the nasty N0x junk. So if the fix means effectively pinning
the cheat on all the time, fixed cars will probably end up burning more fuel
with less top-end power.

~~~
kw71
I know that a lean burning petrol engine will emit more NOx, but as an
American who is not a truck mechanic I don't really know much about diesel.
Does it work the same way in the diesel cycle? On the other hand, I am
reasonably sure that more fuel = more CO2 emissions (or whatever emissions are
catalyzed into CO2.)

~~~
sandworm101
It's the same basic chemistry. You've got O2+N2 (air) plus hydrocarbon
(H-C=C-H sort of things) all mixed together and heated. Ideally all the 02
bonds with the H and C to form C02 and H20. If the mixture is lean and hot
enough then there isn't enough H and C for all the O2 and it instead bonds
with the N2 to form NOx.

The only real difference with the diesel is that the hydrocarbons are longer,
which is why diesel is thicker and less volatile. Diesel needs to be hotter to
break down these longer hydrocarbons and this is achieved via a higher
compression ratio (14:1 instead of 10:1). That extra heat is an issue for N0x
production if the mixture gets too lean. But if the mix is too rich, with not
enough 02 for all the H and C, then you get incomplete combustion. That black
soot is essentially just carbon that couldn't find any oxygen to bond with.

To avoid soot, so-called clean diesels run slightly lean and then rely on a
catalytic converter to turn any N0x back into N2 and O2, but a dry cat can
only go so far. BMW and others inject urea into the cat where it become
ammonia (NH3). The O in the NOx grabs the H from the NH3 and the two Ns form
N2. NOx + NH3 = N2 + H20.

------
andor
Not very convincing.

On most cars, you can't _completely_ turn off traction control. The "ESP off"
button is there driving with tire chains, it just increases the threshold of
the safety systems but doesn't disable them. That could explain the warnings
in the dashboard, and also the reduced torque. High torque on low-traction
surfaces leads to wheel spin.

~~~
dghughes
Off topic but I hate cars that don't allow traction control (TC) to be turned
off it can be dangerous.

We had Ford Transit vehicles at work and in the winter if there is a lot of
snow the TC will kill 90% of engine power trapping you in the snow.

I've almost been killed by TC on a Ford Transit activating at the worst
moment. When I first drove the vehicle I had the vehicle stop abruptly when
the TC kicked in and a car almost ran into the back of me.

You can disable it by taking out a fuse but it also disables the ABS and
airbag. Plus it was a leased company vehicle so I couldn't do that anyway.

It's like a practical joke here kill 90% of the engine power at the worst
moment.

For you warm climate people drifts of snow at the end of driveways or on the
road are common in winter regions. Usually you power through them if possible,
wheels straight, foot down on the pedal all the way.

In the end I found out I could go fast and then put the vehicle in neutral and
coast through as best I could.

I should say for ice TC is fantastic but it's not common for pure ice to be on
a road, some parts but most times it would be melted by applied road salt.

~~~
jessaustin
ISTM the Transit's TC might just not be tuned very well? That might be related
to the model year or might be something a Ford dealer could fix with a
firmware update. Friends I've had in snowy places have sworn by their AWD
vehicles. Personally I've scared myself half to death driving a big RWD truck
in the snow.

~~~
dghughes
Living in a snowy climate yes AWD and 4X4 are great yes (even FWD) it's the
traction control that's the problem.

You can tell it wasn't designed by people who have ever seen snow. The Ford
Transit is manufactured in Turkey but I don't know if that's a reason for the
terrible traction control (and poor heat, and failing wheel bearings, and
always cracking windshields).

------
kinofcain
The most telling aspect of this is not the 10% power drop but the massive
torque drop at lower RPMs. That indicates that VW is limiting turbo boost at
low RPMs while in this mode. That makes sense, as increasing turbo boost
increases pressure, which increases combustion temps, which increases NOx
production.

------
Animats
VW owners may be looking at the kind of retrofits California requires for
older heavy trucks.[1] The muffler is replaced with a filter which has to be
cleaned periodically. This seems to be working; it's rare to see a truck
belching smoke in California. So there's a path to a fix available.

[1]
[http://www.arb.ca.gov/msprog/truckstop/truckstop.htm](http://www.arb.ca.gov/msprog/truckstop/truckstop.htm)

~~~
ugh123
I always see large trucks on I-5 regularly spewing huge amounts of smoke when
they hit the gas. It gets so bad that people speed around them to avoid the
smog getting into their cars. This is mostly large commercial semis and dump
trucks. Are you talking about passenger cars?

~~~
sandworm101
The black stuff from diesels is soot, not smog. Soot is just unburnt carbon.
The term 'smog' covers a whole manner of nasty chemicals, mostly oxides of
nitrogen and sulfur.

Soot is relatively harmless compared to smog. A diesel producing soot is
running rich and therefore is arguably cleaner than a "clean-diesel" running
lean and pumping out oxides. Those carbon-belching trucks are far better for
your lungs than the smoke-free VWs pumping out N0x. Beware the pollution you
cannot see.

~~~
marincounty
Good post! Years ago I had a slight head gasket leak, and needed to drive the
vechicle just one more day before I took the head off and did the nasty job.

I had a little bit of extra smoke comming out of the tail pipe, and I got
pulled over by a Police Officer. I told the officer, the extra smoke was
mainly water vapor, but was still expecting a ticket.

Well, the officer said he used to be a mechanic, and knew I was likely telling
the truth. He let me off with a warning.

I think those days are over though. I have seen people freak out over the wiff
of cigarette smoke. Yesterday, I heard this lady yelling at a janitor over
bleach smell. She squelched , "You're giving me cancer!". I don't think he
understood English, and was probally better off?

I'm all for cleaning up the air, but people need to educate themselves on what
exactly is going to give them, or the environment problems.

~~~
sandworm101
A leaky head gasket will usually produce a white smoke that smells a bit like
pot smoke. That's the ethylene glycol in the antifreez/coolant being burnt.

The new anti-bleach craze is laughable. I had one woman at the local dog beach
tell me "You know bleach is the same chlorine they use in swimming pools and
we know that stuff causes cancer." I spend at least an hour a day swimming
laps. Have done so since I was eight. And I at one point lived in a country
where we regularly added small amounts of bleach to drinking water to
disinfect it. If chlorine causes cancer I am doomed.

------
codezero
Wow, only a 10% loss? That hardly seems worth cheating... then again, I don't
run a car company, so I guess it's the kind of thing they think they need to
do. bummer.

~~~
Tloewald
The real question is how it converts to mpg. A whole bunch of manufacturers
have gotten in trouble for exaggerating fuel economy, and I for one certainly
consider it when comparing cars (to an irrational degree, in fact). If it's
the difference between 38mpg and 34mpg then that might be worth lying about.

~~~
toomuchtodo
Especially if you're trying to meet US CAFE standards. Curious if VW is going
to need to buy a bunch of ZEV credits now in CA (with Tesla being the primary
beneficiary).

~~~
monopolemagnet
Both CAFE and Smog Check-style programs are gamed terribly, across multiple
manufacturers... but VW gets the blame, which it rightly deserves.

Testing of emissions needs to happen at the tailpipe while driving with mobile
equipment in the real-world with certain types of traffic / road conditions.

Mileage needs to be calculated by metered fuel measurement on a test track
with both highway- and (stop-and-go traffic) city-driving.

In addition to either two, Tesla vehicles and other full electric vehicles
cannot come quickly enough to supplant gasoline/diesel/CNG/LNG/flex fuel/etc.

PS: I just California Smog Check'ed my '85 Vanagon, which has direct-port fuel
injection, mass-airflow sensor and rudimentary "computer" (Digijet) after
replacing the catalytic converter, O2 sensor and having a VW specialist shop
tune it up. NOx (nitrous oxides) went from barely failing 15 and 25 mph limits
to near zero. HC (hydrocarbons) and CO were also barely detectible. Emissions
on it (a 90 hp motor) are currently at the levels of a PZEV or a new vehicle,
and it gets 24 (real-world) MPG (9.8 L/100km).

Already, CA Smog Check station owners are foreseeing additional mandated
equipment investments to perform tests on modern vehicles not just via the
OBDII port under the steering wheel. This is a good thing but it's hard to
sell small-business owners on capital and labor expenses up against the status
quo/sunk costs fallacy.

------
nl
So are they claiming that the software drops the engine into "cheat" mode by
detecting when the front wheels were not spinning (which implies dyno-
testing)?

Is it confirmed that is how cheat mode worked?

If I were writing this I'd be more inclined to look for known test cycle
behaviour (ie, accelerate for a known time, then constant speed then stop,
start etc etc) and drop into cheat mode when it is detected. I guess this
could be a problem for unknown cycles though?

~~~
Sanddancer
Other groups have stated the same thing [1]. The car already has to detect
dyno testing to turn off traction control and other things that are dangerous
under these conditions, adding a flag to tweak the mixture the car works with
under speed isn't so difficult after that. Trying to detect a pattern would
lead to much more complicated logic, especially if you get a tester who
decides to do things in a different order.

[1] [http://www.consumerreports.org/cro/cars/volkswagen-
emissions...](http://www.consumerreports.org/cro/cars/volkswagen-emissions-
cheat-exploited-test-mode)

------
trhway
>if you look lower on the RPM curve the difference is significant. The car
lost 15 horsepower around 2,800 RPM, and 32 lb-ft of torque near 2,700 rpm

so, looking at the picture, the power/torque at 2800rpm is about 120/260 while
in "cheater" mode it is 105/228\. And that ratio is preserved through whole
2000-3000rpm range, the range that really matters as most of the driving
happens here.

------
msravi
So now, given that "fixing" the problem will cause power loss, and
consequently adversely affect fuel economy, wouldn't a number of VW owners opt
not to bring in their vehicles for the recall? What's the incentive for VW
owners to voluntarily bring in their cars for a regressive (in terms of power
and mpg) fix?

~~~
chubs
I believe VW have promised to _replace everyones entire engines_. I'm
stupefied over how much this will cost, i've seen numbers around to 100B mark.
Their market cap is somewhere near half of that. Presumably they think it's
better than the brand damage otherwise. I think it's fair to assume they'll go
bankrupt over this.

~~~
gnoway
Do you have a link for this? Replacing even 500k engines in the US is indeed
stupefying.

------
ck2
The BBC did a real-world driving test and directly examined the exhaust for
NOx emmisions and they were exponentially worse than the lab results.

If the exhaust was going into your car, you'd be fatally poisoined in short
order.

So thanks for the cancer you've given to all the pedestrians and cyclists VW
(and all the other lying corporate a-holes).

~~~
KMag
Not all toxins are carcinogenic. In particular, VW seems to have been leaning
out the mixture, resulting in lower levels of soot and carcinogenic
polyaromatics. I'm not aware of any studies showing oxides of nitrogen to be
carcinogenic.

------
SQL2219
Why would a company take such a huge risk for a paltry 10% gain in engine
power, and a probably even smaller gain in mpg? This seems like a very dumb
thing to do.

~~~
sschueller
In order to sell cars. The competition is/was doing it also and it was widely
known practice. [1] For some reason VW is getting all the blame.

[1]
[https://www.youtube.com/watch?v=pjUr3RQRERM](https://www.youtube.com/watch?v=pjUr3RQRERM)

------
cmavr8
Offtopic but I couldn't help it... It looks like they're still running win xp!
I suppose the pc is air gapped yeah..

