VW dieselgate continues, tries to prove diesel fumes are OK

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#1950028 1-Feb-2018 12:30

kryptonjohn:

Doesn't matter now. Diesel is close to dead as far as new vehicles are concerned. Dieselgate and excessively restrictive emission controls have killed it.

Don't agree with "excessively restrictive".

Diesel is a heart-disease-causing, cancer-promoting dirty fuel that means schools and daycare centre aren't allowed within 150m of any motorway and 50m of any major road.

It's poison.

It shouldn't even be legal.......and then when you take the CO2 into account it's just that much worse.

It's an awful fuel.

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#1950060 1-Feb-2018 12:48

Linuxluver:

kryptonjohn:

Doesn't matter now. Diesel is close to dead as far as new vehicles are concerned. Dieselgate and excessively restrictive emission controls have killed it.

Don't agree with "excessively restrictive".

Diesel is a heart-disease-causing, cancer-promoting dirty fuel that means schools and daycare centre aren't allowed within 150m of any motorway and 50m of any major road.

It's poison.

It shouldn't even be legal.......and then when you take the CO2 into account it's just that much worse.

It's an awful fuel.

Yeah, nah. Diesel's run passenger and freight transport for a century and it is more efficient and produces less CO2 than petrol. Leaded petrol over the years would have done far, far more damage.

Make diesel illegal and you won't have your electric car. It could never be built and delivered to you without diesel.

Schools restricted within 150m of a motorway or 50m of a major road? Where on earth did you get that from?

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#1950125 1-Feb-2018 14:13

kryptonjohn:

Linuxluver:

kryptonjohn:

Doesn't matter now. Diesel is close to dead as far as new vehicles are concerned. Dieselgate and excessively restrictive emission controls have killed it.

Don't agree with "excessively restrictive".

Diesel is a heart-disease-causing, cancer-promoting dirty fuel that means schools and daycare centre aren't allowed within 150m of any motorway and 50m of any major road.

It's poison.

It shouldn't even be legal.......and then when you take the CO2 into account it's just that much worse.

It's an awful fuel.

Yeah, nah. Diesel's run passenger and freight transport for a century and it is more efficient and produces less CO2 than petrol. Leaded petrol over the years would have done far, far more damage.

Make diesel illegal and you won't have your electric car. It could never be built and delivered to you without diesel.

Schools restricted within 150m of a motorway or 50m of a major road? Where on earth did you get that from?

Pretty sure Westlake girls highschool is wedged between NZ busiest motorway and one of the busiest suburban streets with heavy traffic.......

kryptonjohn

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#1950127 1-Feb-2018 14:17

I was thinking of my old school, Auckland Grammar on one side of the motorway, and St Peters on the other.

Mind you, if I spent those 5 years sucking in bad fumes it could explain all sorts of things...

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#1950412 2-Feb-2018 02:11

kryptonjohn:

I would dearly love to delete the EGR on my VW but it means getting an P0401 insufficient flow error and nobody seems to be able to defeat that.

@kryptonjohn figure out how that flow is being measured. If your VW has an air flow meter, the airflow as reported by the AFM will drop when the EGR valve is open. If the ECU opens the EGR valve, but the reported airflow doesn't change, then the ECU knows that there is low or no EGR flow. One method I have seen to fool this, the vehicle had an AFM that outputs a variable 0-5V signal to the ECU, and the EGR valve was either fully open or fully closed. The EGR solenoid used negative switching. So the right value resistor between the AFM signal line and the EGR switched negative line, got the right amount of voltage change on the AFM signal to fool the ECU.

In saying that, some VWs use really complex EGR systems with multiple flow paths, exhaust temp sensors. (might be doing PID feedback from the EGT sensors as well) And things like cylinder pressure sensors. So their system will be alot harder than most to fool. So EGR disable by ECU reflash would be the best option if available.

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#1950413 2-Feb-2018 02:30

Lastman:

The problem is NOX is a major factor in fine particle pollution deaths. The figure quoted seems to be about 5000 premature deaths in Europe per year, about half of all fine particle related deaths. And vehicles were the major contributor. Add to that the masive cost on healthcare of treating all the related disorders.

The effect on the environment isn’t quite as benign as you suggest, also.

The dieselgate vehicles only reduced NOX when they were being tested, otherwise they operated in more fuel efficient, less exhaust damaging modes. European laws were strict but the fine print allowed companies to certify vehicles that had high NOx emissions so diesels in Europe emitt high levels of NOx despite the regulations.

Lots of earlier diesel vehicles have EGR and other NOx reduction systems, but no particulate filters. How many extra deaths have been caused by those unnecessary particulate emissions? EGR systems have been fitted to diesel vehicles long before particulate filters have existed.

Also CO2 emissions cause deaths due to things like droughts and other natural disasters caused by climate change due to man made global warming. Heck, whole countries are predicted to disappear due to sea level rise.

Note also that alot of city based NOx emissions will also come from gas appliances. And what about NOx emissions from jet engines? They are not subject to any NOx emissions regulations.

Again, it is partly related to politics. As small disappearing island countries don't have much geopolitical clout.

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#1950414 2-Feb-2018 02:48

Fred99:

Not sure if this applies - but it seems that time is needed after new cars are released - for hackers to eventually decipher/reverse engineer the ECUs - or someone working in the industry to leak information perhaps.

EGR should NOT impact significantly on fuel efficiency - if it's working correctly. It's only open/recirculating at low throttle setting, the EGR valve should close when accelerating. The bigger issue (IMO) is the accumulation of greasy mess in the intake, possible clogging of sensors etc - and especially when many makers don't exactly make it easy to remove and/or clean out the intake system.

Some VW group petrol engines (and cars from other makers) with "FSI" are also prone to carboning up the intake ports - the cause isn't related to EGR - but that gets the blame. If it's a V6, then labour cost to clean the intake ports can be a bit scary.

EGR actually does have a massive effect on fuel efficiency. Have a read of heat engine theory - short answer, the higher the combustion temps, the higher the efficiency of an engine.

When you are cruising along at say 50km/hr, your engine will have to be outputting a set amount of power to maintain that speed. If you disable the EGR, combustion temps increase, the engine power output increases for that given fuel usage. You then have to lift off the accelerator pedal a little, to keep the vehicle at 50KM/Hr. You are now using less fuel to maintain the same speed.

Agree that EGR is not active at max acceleration.

As for VW FSI petrol engines, and of course the infamous Mitsubishi GDI engines. The EGR is used for controlling preignition (knock), by using the EGR to vary combustion temps. Those engines normally require high octane petrol. If you use low octane petrol, the ECU tries to compensate by increasing the amount of EGR flow. This in turn causes the inlet manifolds to carbon up quicker.

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#1950429 2-Feb-2018 07:04

Aredwood:

kryptonjohn:

I would dearly love to delete the EGR on my VW but it means getting an P0401 insufficient flow error and nobody seems to be able to defeat that.

@kryptonjohn figure out how that flow is being measured. If your VW has an air flow meter, the airflow as reported by the AFM will drop when the EGR valve is open. If the ECU opens the EGR valve, but the reported airflow doesn't change, then the ECU knows that there is low or no EGR flow. One method I have seen to fool this, the vehicle had an AFM that outputs a variable 0-5V signal to the ECU, and the EGR valve was either fully open or fully closed. The EGR solenoid used negative switching. So the right value resistor between the AFM signal line and the EGR switched negative line, got the right amount of voltage change on the AFM signal to fool the ECU.

In saying that, some VWs use really complex EGR systems with multiple flow paths, exhaust temp sensors. (might be doing PID feedback from the EGT sensors as well) And things like cylinder pressure sensors. So their system will be alot harder than most to fool. So EGR disable by ECU reflash would be the best option if available.

I have a guy who could code this out of your ECU, Let me know if you'd like his details.

Cheers

kryptonjohn

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#1950438 2-Feb-2018 08:13

Coil:

Aredwood:

kryptonjohn:

I would dearly love to delete the EGR on my VW but it means getting an P0401 insufficient flow error and nobody seems to be able to defeat that.

@kryptonjohn figure out how that flow is being measured. If your VW has an air flow meter, the airflow as reported by the AFM will drop when the EGR valve is open. If the ECU opens the EGR valve, but the reported airflow doesn't change, then the ECU knows that there is low or no EGR flow. One method I have seen to fool this, the vehicle had an AFM that outputs a variable 0-5V signal to the ECU, and the EGR valve was either fully open or fully closed. The EGR solenoid used negative switching. So the right value resistor between the AFM signal line and the EGR switched negative line, got the right amount of voltage change on the AFM signal to fool the ECU.

In saying that, some VWs use really complex EGR systems with multiple flow paths, exhaust temp sensors. (might be doing PID feedback from the EGT sensors as well) And things like cylinder pressure sensors. So their system will be alot harder than most to fool. So EGR disable by ECU reflash would be the best option if available.

I have a guy who could code this out of your ECU, Let me know if you'd like his details.

Cheers

PM Sent!

Fred99

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#1950743 2-Feb-2018 14:29

Aredwood:

EGR actually does have a massive effect on fuel efficiency. Have a read of heat engine theory - short answer, the higher the combustion temps, the higher the efficiency of an engine.

I know that's what "everyone says" but that's simply not correct for any modern engine with properly designed EGR system operating correctly. To say it has a "massive effect" is clearly wrong.

If you disagree and have good evidence with references, I invite you to edit the wikipedia entry and see how you go:

A properly operating EGR can theoretically increase the efficiency of gasoline engines via several mechanisms:

Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses.
Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke.
Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC (Top Dead-Center), rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is minor compared to the first two.

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#1950745 2-Feb-2018 14:37

It's seems obvious to me that EGR reduces economy. It's feeding exhaust into the the intake which means less oxygen and it's feeding hot gas into the intake which means less oxygen.

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#1950769 2-Feb-2018 15:36

Sometimes things that seem "obvious" can be completely wrong.

Don't get me wrong - I hate EGR for added complexity and maintenance issues, but it's not a performance or economy issue - at least when it's working correctly.

It's also illegal to tamper with or disable EGR on vehicles (after ???? date of manufacture - not sure when from when this applied) in NZ, but nobody is checking, even if they were - then if it's disabled only by an ECU setting then it could be just as easily enabled again before the vehicle was taken in to be routinely tested (as in California for example).

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#1950782 2-Feb-2018 15:50

Fred99:

Sometimes things that seem "obvious" can be completely wrong.

Don't get me wrong - I hate EGR for added complexity and maintenance issues, but it's not a performance or economy issue - at least when it's working correctly.

It's also illegal to tamper with or disable EGR on vehicles (after ???? date of manufacture - not sure when from when this applied) in NZ, but nobody is checking, even if they were - then if it's disabled only by an ECU setting then it could be just as easily enabled again before the vehicle was taken in to be routinely tested (as in California for example).

It's not illegal in NZ to delete EGR and no testing station is equipped to detect it anyway. The sole emission test in NZ is that the vehicle not produce visible clouds of smoke.

Well, people who know a lot more about this than I do have told me EGR negatively impacts economy and the fundamentals I mentioned support this. I'd like to hear an explanation of how EGR could possibly *not* impact economy.

[edit] you did reference a wiki on EGR that concluded thus:

"Though engine manufacturers have refused to release details of the effect of EGR on fuel economy, the EPA regulations of 2002 that led to the introduction of cooled EGR were associated with a 3% drop in engine efficiency, bucking a trend of a .5% a year increase"

Fred99

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#1950846 2-Feb-2018 18:07

kryptonjohn:

It's not illegal in NZ to delete EGR and no testing station is equipped to detect it anyway. The sole emission test in NZ is that the vehicle not produce visible clouds of smoke.

Yes it is - the model year this came into effect was 2007

https://www.nzta.govt.nz/resources/rules/vehicle-exhaust-emissions-2007-qa.html#removalandtampering

So if you do modify a post 2007 vehicle, then you'd be best to ensure that those modifications are reversible - because the regulations certainly are in place - all that's needed to cause some big problems would be if NZ adopted emissions testing as per California.

kryptonjohn:

Well, people who know a lot more about this than I do have told me EGR negatively impacts economy and the fundamentals I mentioned support this. I'd like to hear an explanation of how EGR could possibly *not* impact economy.

[edit] you did reference a wiki on EGR that concluded thus:

"Though engine manufacturers have refused to release details of the effect of EGR on fuel economy, the EPA regulations of 2002 that led to the introduction of cooled EGR were associated with a 3% drop in engine efficiency, bucking a trend of a .5% a year increase"

The fundamentals were explained in that wiki article.

That was diesel specific comment - and from 15 years ago - before common rail was widely adopted (ie VW used systems like unit injectors "Pumpe Düse" with far less electronic control of injection than more modern designs). Better control of injectors / engine mapping should probably negate issues caused by EGR.

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#1950992 3-Feb-2018 02:38

Fred99:

Aredwood:

EGR actually does have a massive effect on fuel efficiency. Have a read of heat engine theory - short answer, the higher the combustion temps, the higher the efficiency of an engine.

I know that's what "everyone says" but that's simply not correct for any modern engine with properly designed EGR system operating correctly. To say it has a "massive effect" is clearly wrong.

If you disagree and have good evidence with references, I invite you to edit the wikipedia entry and see how you go:

A properly operating EGR can theoretically increase the efficiency of gasoline engines via several mechanisms:

Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses.
Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke.
Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC (Top Dead-Center), rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is minor compared to the first two.

Quoting from the same wikipedia article, but the diesel engine section instead of the petrol engine section. (Since the OP and most of the rest of this thread is in relation to diesel engines)

In modern diesel engines, the EGR gas is cooled with a heat exchanger to allow the introduction of a greater mass of recirculated gas. Unlike spark-ignition engines, diesels are not limited by the need for a contiguous flamefront; furthermore, since diesels always operate with excess air, they benefit from EGR rates as high as 50% (at idle, when there is otherwise a large excess of air) in controlling NOx emissions. Exhaust recirculated back into the cylinder can increase engine wear as carbon particulates wash past the rings and into the oil.[8]

Since diesel engines are unthrottled, EGR does not lower throttling losses in the way that it does for SI engines. Exhaust gas—largely nitrogen, carbon dioxide, and water vapor—has a higher specific heat than air, so it still serves to lower peak combustion temperatures. However, adding EGR to a diesel reduces the specific heat ratio of the combustion gases in the power stroke. This reduces the amount of power that can be extracted by the piston. EGR also tends to reduce the amount of fuel burned in the power stroke. This is evident by the increase in particulate emissions that corresponds to an increase in EGR.[9] [10]

Particulate matter (mainly carbon) that is not burned in the power stroke is wasted energy. Stricter regulations on particulate matter (PM) call for further emission controls to be introduced to compensate for the PM emission increases caused by EGR. The most common is a diesel particulate filter in the exhaust system which cleans the exhaust but causes a constant minor reduction in fuel efficiency due to the back pressure created. The nitrogen dioxide component of NOx emissions is the primary oxidizer of the soot caught in the diesel particulate filter (DPF) at normal operating temperatures. This process is known as passive regeneration. Increasing EGR rates cause passive regeneration to be less effective at managing the PM loading in the DPF. This necessitates periodic active regeneration of the DPF by burning diesel fuel in the oxidation catalyst in order to significantly increase exhaust gas temperatures through the DPF to the point where PM is quickly burned by the residual oxygen in the exhaust.

By feeding the lower oxygen exhaust gas into the intake, diesel EGR systems lower combustion temperature, reducing emissions of NOx. This makes combustion less efficient, compromising economy and power. The normally "dry" intake system of a diesel engine is now subject to fouling from soot, unburned fuel and oil in the EGR bleed, which has little effect on airflow. However, when combined with oil vapor from a PCV system, can cause buildup of sticky tar in the intake manifold and valves. It can also cause problems with components such as swirl flaps, where fitted. Diesel EGR also increases soot production, though this was masked in the US by the simultaneous introduction of diesel particulate filters.[11] EGR systems can also add abrasive contaminants and increase engine oil acidity, which in turn can reduce engine longevity.[12]

Though engine manufacturers have refused to release details of the effect of EGR on fuel economy, the EPA regulations of 2002 that led to the introduction of cooled EGR were associated with a 3% drop in engine efficiency, bucking a trend of a .5% a year increase.[13]

That above section backs up what I have said earlier. A whole host of problems, with the only benefit being NOx reductions.

As for commonrail diesel engines, main reason for using commonrail. Is it gives the ability to inject diesel at any time. For example, diesel is injected during the exhaust stroke to do a DPF "burnoff". But commonrail is both more complex, and my understanding is that the commonrail pump robs more engine power. Due to the need to constantly maintain very high fuel pressures. While the high injection pressures in distributor and unit injector systems are only produced while fuel is actively being injected.

Also have a read of the Talk section of the same Wikipedia page. There are alot of challenges to the claim about EGR increasing efficiency in petrol engines.

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