Car Emmisisons (was Thunderf00t thread)

[Psi]

Surely they can just query the VW computer to check the current emissions level.   

[Siwastaja]

Not in the UK MoT. They still use an exhaust probe and rev the engine.

Of course, that's exactly why VW developed the piece of firmware which detects the revving pattern during emissions test and enter a lower emission mode. If this was just an OBD readout it would have been much easier to fake, just lie.

[tom66]

Not in the UK MoT. They still use an exhaust probe and rev the engine.

Of course, that's exactly why VW developed the piece of firmware which detects the revving pattern during emissions test and enter a lower emission mode. If this was just an OBD readout it would have been much easier to fake, just lie.

It was more complicated than that, they were detecting the precise speed / distance curve that the NEDC profile matched and then only enabling cheater mode when air pressure and temperature were just like all the test labs in Germany (apparently they are all around a similar altitude, coincidentally, and temperature tends to be controlled well for result repeatability).

As a result, activating the cheater code in normal operation was nearly impossible, so the cars would always have high NOx on the road.

[nctnico]

On a petrol car failing emissions is either an O2 (lambda) sensor (cost between 50 and 100 euro) or the catalythic converter (costing between 400 and 1100 euro). These are not amounts which buy you another car. So far I have not had a catalythic converter failure even with very high mileage.

Really, all that simple? How about worn out engine that needs a very expensive engine block repair or replacement?

Getting a replacement engine is likely cheaper. By the time an engine is worn, there are enough lower mileage replacement engines on the market. For my car such an engine costs around 600 to 700 euro. Probably another 700 to 800 euro to have it swapped at a garage. For those seeking corner cases: ofcourse you are smart and don't buy an uncommon car to begin with. The more common a car is, the cheaper the parts are.

BTW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

Sounds like nonsense, and good luck asking for that here. Only real emission testing.

This is the procedure as described in the Netherlands' MOT testing protocol for cars sold after 2005. Reason I know is that on my car the engine warning light came on due to an emissions issue (catalythic converter / O2 sensor issue) a couple of months ago. Since it was about time for the MOT, I read up on what the test requirement c.q. procedure is.

Reving an engine for emission testing is a time consuming job as they have to let the engine run long enough so it is hot and even then there is a risk of snapping the timing belt or cause other damage. Back in the old days every garage over here explicited stated (both through a sign and telling the customers) to not accept liability for damage from doing emission testing (especially for diesel engines).

[AVGresponding]

Pretty sure there's an age limit on cars in the UK

nope,and if you know were to look you can even find leaded petrol to keep your old jalopy on the road

Old cars need to pass annual MOT testing, yes?

How often do old cars fail MOT and get sent to the scrapyard?

Old cars, inadequately maintained, generally get scrapped when its more expensive to fix them than replace them. MOTs don't change that very much. They just enforce that people don't let things get dangerously bad before taking action. Cars in generally good shape fail their MOT all the time, as a suspension bush may have excessive wear, or a brake disc may have excessive rust (usually the back ones). A car has to be really old, or perhaps very rare, for parts to be unavailable. It comes down to cost. Massive body rust can be a killer.

The MOT failure rate is effectively a de facto fleet turnover rate.  It may not be an explicit vehicle age limit, but it effectively forces old, potentially higher polluting cars from the road.

Going to try and pick apart this nested quote as best I can..

There is an age limit for cars in the UK, but it doesn't work the way you seem to think it does; when a car reaches 40 years old, as long as it had a valid MOT at the time, it is exempt from future testing, and is also exempt from VED.
If a car over 40 years old wasn't road legal when it transitioned, it will have to pass an MOT before being allowed back on the road, but will thereafter be exempt.

Leaded petrol is not legal to use in the UK, and hasn't been since 2000. Lead Replacement Petrol (LRP) is what you have to use, if your classic really can't handle regular unleaded. This is now only in the form of an additive you put in unleaded from the pump; up until the early 2000's you could get it pumped on the forecourt. It isn't lead-based.

Cars don't need to be old for parts to be unavailable; it's no secret that a well known EV manufacturer prioritises parts to build new cars rather than repair existing ones, and they are far from unique in this, it's becoming the norm, and in fairness has been going this way for several decades now, as a consequence of the "just-in-time" stocking practice, and the change in business model which has seen profit move from service and repair to purchase finance.

Modern cars are more polluting than older ones. This is an intentionally out of context statement designed to grab your attention, but it's true nevertheless; for a given context.
Modern cars are heavier and the fashion is for the bigger variants, so even though engines have become cleaner per unit of fuel burned, they need to burn more fuel to move the vehicle.
EVs and heavier vehicles in general cause more rubber pollution due to extra tyre wear. This is non-trivial, and tyre manufacturers are having to research less harmful and more durable compounds.



In the past, cars would be forced off the road due to chassis corrosion and serious mechanical failure if they survived long enough (80+ thousand miles, unless meticulously maintained). Nowadays, they die mostly due to ECM failure of one sort or another, or mechanical failure of a single part in an assembly that the manufacturer refuses to supply in any form other than a complete (and stupidly expensive) unit.

[nctnico]

Not in the UK MoT. They still use an exhaust probe and rev the engine.

Of course, that's exactly why VW developed the piece of firmware which detects the revving pattern during emissions test and enter a lower emission mode. If this was just an OBD readout it would have been much easier to fake, just lie.

It was more complicated than that, they were detecting the precise speed / distance curve that the NEDC profile matched and then only enabling cheater mode when air pressure and temperature were just like all the test labs in Germany (apparently they are all around a similar altitude, coincidentally, and temperature tends to be controlled well for result repeatability).

As a result, activating the cheater code in normal operation was nearly impossible, so the cars would always have high NOx on the road.

High NOX on the road yes. But emissions testing is in a no-load condition so in theory the software can detect the emissions test cycle as well.

[tom66]

Video on the NOx cheat from a researcher:
https://youtube.com/watch?v=MLZLxzYCarw

The very interesting bit is from about 51 minutes onwards... those are some suspicious curves.

[tggzzz]

Not in the UK MoT. They still use an exhaust probe and rev the engine.

Of course, that's exactly why VW developed the piece of firmware which detects the revving pattern during emissions test and enter a lower emission mode. If this was just an OBD readout it would have been much easier to fake, just lie.

It was more complicated than that, they were detecting the precise speed / distance curve that the NEDC profile matched and then only enabling cheater mode when air pressure and temperature were just like all the test labs in Germany (apparently they are all around a similar altitude, coincidentally, and temperature tends to be controlled well for result repeatability).

As a result, activating the cheater code in normal operation was nearly impossible, so the cars would always have high NOx on the road.

Compiler writers use similar techniques to cheat benchmarking: recognise the benchmark code, and substitute optimised output which would not otherwise be derived from the source code.

That was done in the 90s (?Sun?) and is still occurring.

SPEC says it will no longer be publishing SPEC CPU 2017 results for Intel CPUs running a specific version of the Intel compiler, citing displeasure over an apparent targeted optimization for a specific workload (via ServeTheHome and Phoronix) that essentially amounts to cheating. ...
The disclaimer that it is now attached to over 2,600 SPEC CPU 2017 results states, "The compiler used for this result was performing a compilation that specifically improves the performance of the 523.xalancbmk_r / 623.xalancbmk_s benchmarks using a priori knowledge." This means the compiler (in this case, Intel's oneAPI DPC++/C++ Compiler) was not optimized for the kind of workload the two SPEC CPU 2017 benchmarks in question test, but specifically the two benchmarks themselves

https://www.tomshardware.com/pc-components/cpus/spec-invalidates-2600-intel-cpu-benchmarks-says-companys-compiler-used-unfair-optimizations-that-boosted-performance

[coppice]

Not in the UK MoT. They still use an exhaust probe and rev the engine.

Of course, that's exactly why VW developed the piece of firmware which detects the revving pattern during emissions test and enter a lower emission mode. If this was just an OBD readout it would have been much easier to fake, just lie.

It was more complicated than that, they were detecting the precise speed / distance curve that the NEDC profile matched and then only enabling cheater mode when air pressure and temperature were just like all the test labs in Germany (apparently they are all around a similar altitude, coincidentally, and temperature tends to be controlled well for result repeatability).

As a result, activating the cheater code in normal operation was nearly impossible, so the cars would always have high NOx on the road.

That is what I never figured out about that scandal. They looked specifically for the approvals cycle pattern, and played tricks. However, that won't work for regular annual inspections. Don't most countries actually do a simple measurement at the tailpipe, like the UK MOT does from the third year onwards?

[nctnico]

As I wrote before: MOT emission measurements are done in no-load conditions. Very easy to test by the car's software and the vehicle performance isn't affected.

[magic]

BTW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

Sounds like nonsense, and good luck asking for that here. Only real emission testing.

This is the procedure as described in the Netherlands' MOT testing protocol for cars sold after 2005. Reason I know is that on my car the engine warning light came on due to an emissions issue (catalythic converter / O2 sensor issue) a couple of months ago. Since it was about time for the MOT, I read up on what the test requirement c.q. procedure is.

So you just pull the check engine lightbulb and it's OK?

[nctnico]

BTW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

Sounds like nonsense, and good luck asking for that here. Only real emission testing.

This is the procedure as described in the Netherlands' MOT testing protocol for cars sold after 2005. Reason I know is that on my car the engine warning light came on due to an emissions issue (catalythic converter / O2 sensor issue) a couple of months ago. Since it was about time for the MOT, I read up on what the test requirement c.q. procedure is.

So you just pull the check engine lightbulb and it's OK?

No. The OBD reader (as required per NL MOT test procedure) will still show the error. I highlighted the part you missed in bold 

[magic]

Let's highlight a different part

TW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

But assuming that they aren't completely stupid and do connect the OBD scanner, I wonder if the ECU authenticates itself to it reliably or if there is a potential market for dummy ECUs which never have any errors? I mean, I doubt that anyone will inspect where the wiring behind the OBD connector goes...

[coppice]

This is the procedure as described in the Netherlands' MOT testing protocol for cars sold after 2005. Reason I know is that on my car the engine warning light came on due to an emissions issue (catalythic converter / O2 sensor issue) a couple of months ago. Since it was about time for the MOT, I read up on what the test requirement c.q. procedure is.

Reving an engine for emission testing is a time consuming job as they have to let the engine run long enough so it is hot and even then there is a risk of snapping the timing belt or cause other damage. Back in the old days every garage over here explicited stated (both through a sign and telling the customers) to not accept liability for damage from doing emission testing (especially for diesel engines).

What did the Netherlands do before 2005? Why were they running the engine in a way that might have damaged it? I don't know what the current UK practice is, but the last time I saw the test conducted they started the engine, then just let it idle for some time while they did other work. When the engine was up to temperature they did a tailpipe test at idle, and with the accelerator depressed enough to reach some specific RPM values. That was a long time ago, but I saw the sensor being inserted in the tailpipe of someone else's car a few months ago, while I was at the garage for something else. The UK government web site says gasoline cars made after 1975 and diesels made after 1980 are checked by a meter in the MOT test. It doesn't give details. I might be misremembering, but I think the car I saw being tested recently was on a rolling road. They definitely use a rolling road for some of the MOT testing.

[nctnico]

Let's highlight a different part

TW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

But assuming that they aren't completely stupid and do connect the OBD scanner, I wonder if the ECU authenticates itself to it reliably or if there is a potential market for dummy ECUs which never have any errors? I mean, I doubt that anyone will inspect where the wiring behind the OBD connector goes...

There are cases where people load different software into the ECU which mimics the presence of a catalythic converter so when reading the status through OBD, everything is fine. But these cars would obviously fail an emissions test which could be performed by the testing station in case of doubts. And the alternative ECU firmware isn't cheap either.

[nctnico]

This is the procedure as described in the Netherlands' MOT testing protocol for cars sold after 2005. Reason I know is that on my car the engine warning light came on due to an emissions issue (catalythic converter / O2 sensor issue) a couple of months ago. Since it was about time for the MOT, I read up on what the test requirement c.q. procedure is.

Reving an engine for emission testing is a time consuming job as they have to let the engine run long enough so it is hot and even then there is a risk of snapping the timing belt or cause other damage. Back in the old days every garage over here explicited stated (both through a sign and telling the customers) to not accept liability for damage from doing emission testing (especially for diesel engines).

What did the Netherlands do before 2005? Why were they running the engine in a way that might have damaged it? I don't know what the current UK practice is, but the last time I saw the test conducted they started the engine, then just let it idle for some time while they did other work. When the engine was up to temperature they did a tailpipe test at idle, and with the accelerator depressed enough to reach some specific RPM values. That was a long time ago, but I saw the sensor being inserted in the tailpipe of someone else's car a few months ago, while I was at the garage for something else. The UK government web site says gasoline cars made after 1975 and diesels made after 1980 are checked by a meter in the MOT test. It doesn't give details. I might be misremembering, but I think the car I saw being tested recently was on a rolling road. They definitely use a rolling road for some of the MOT testing.

From what I've read on the UK MOT testing it looks like emissions testing is done stationary. Some sort of rolling road could be used for testing the shock absorbers or brakes though.

For petrol cars there is a certain RPM at which the emissions needs to be measured:
https://www.snapon.com/diagnostics/uk/kb/training/take-emissions-readings-during-a-petrol-mot-test.htm

However, diesels need to be reved up all the way to the RPM limiter rather quickly (within a second). This will cause maximum stress on the timing belt. https://www.snapon.com/diagnostics/uk/kb/training/take-emissions-readings-during-a-diesel-mot-test.htm

[coppice]

However, diesels need to be reved up all the way to the RPM limiter rather quickly (within a second). This will cause maximum stress on the timing belt. https://www.snapon.com/diagnostics/uk/kb/training/take-emissions-readings-during-a-diesel-mot-test.htm

That's a weird requirement, as that just doesn't happen in normal use. In an automatic you can't even make it happen with a bad gear change.

[langwadt]

Let's highlight a different part

TW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

But assuming that they aren't completely stupid and do connect the OBD scanner, I wonder if the ECU authenticates itself to it reliably or if there is a potential market for dummy ECUs which never have any errors? I mean, I doubt that anyone will inspect where the wiring behind the OBD connector goes...

There are cases where people load different software into the ECU which mimics the presence of a catalythic converter so when reading the status through OBD, everything is fine. But these cars would obviously fail an emissions test which could be performed by the testing station in case of doubts. And the alternative ECU firmware isn't cheap either.

And I suspect the penalties for making, selling, or using emissions cheat devices are severe

[AVGresponding]

BTW, on recent cars with EOBD, emissions testing is done by reading the car's computer in case the engine warning light is on. So if the engine warning light is off, it automatically means a pass for emissions.

Sounds like nonsense, and good luck asking for that here. Only real emission testing.

This is the procedure as described in the Netherlands' MOT testing protocol for cars sold after 2005. Reason I know is that on my car the engine warning light came on due to an emissions issue (catalythic converter / O2 sensor issue) a couple of months ago. Since it was about time for the MOT, I read up on what the test requirement c.q. procedure is.

So you just pull the check engine lightbulb and it's OK?

No, it causes the check check engine light to come on...

[tom66]

It is a requirement in the MoT test for the check engine light to illuminate on ignition on, which is why every car out there will do that when the engine is not started.  Once the engine is started it should extinguish after a few seconds.  If the light doesn't illuminate at all, MoT failed.

There are definitely cheater devices out there that emulate this, but given something like 30% of people don't know how to find their oil dip stick, I am not too worried about these devices being commonplace.  Simply by it being a complicated solution to work around the check engine light and emissions management (like reflashing ECU firmware) excludes the majority of dodgy cars.

It seems most cars near the end of their life fail on either a suspension, bodywork or exhaust component.  The engine, gearbox and the rest of the car is fine, perhaps not running perfectly, but sufficient to move the car around.  I remember some time ago I went to test drive a car that had a faked MOT (the garage/tester must had been paid off or the VIN was fake, something like that).  The car drove fine but you could hear the rear shock absorbers were completely gone.  And the door sill had rust at the seatbelt anchor point - instant MOT fail and likely writes the car off.  I guess despite my general naivety at the time even that car was an obvious heap of crap.

[nctnico]

Shock absorbers and suspension doesn't last a car's lifetime. My rule of thumb is to replace the shock absorbers every 120k km to 150k km. Rubber bushings last a bit longer but will need replacing as well. It is amazing how much difference (improvement!) it makes in the way a car handles after doing the replacement.

[coppice]

Shock absorbers and suspension doesn't last a car's lifetime. My rule of thumb is to replace the shock absorbers every 120k km to 150k km. Rubber bushings last a bit longer but will need replacing as well. It is amazing how much difference (improvement!) it makes in the way a car handles after doing the replacement.

You can't put a lifetime on parts like that. On some cars suspension bushes wear out fast. On others they pretty much last until the rubber parts degrade with age. I suspect a lot of shock absorbers get replaced when its just the bushes at the ends wearing out.