GolfGTIforum.co.uk
Model specific boards => Golf mk7 => Topic started by: dean5125 on 03 January 2020, 13:10
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Hi all,
Hope you all had a good xmas and new year? :smiley:
In fear of sounding stupid this question is only based on previous experience and a lack of knowledge regarding the GPF filters nowadays!
So a few years ago I had a brand new BMW 520d and due to a short work commute shortly after buying it seemed to be doing an active DPF cycle a lot, resulting in a rougher tick over and a real 'booming' exhaust note! (really quite loud for a usually silent diesel exhaust) So my current (utterly amazing) GTI performance seems to do the same from time to time, ok it remains silky smooth but definitely has the booming exhaust note for 5 minutes every so often. So my question is do they still have an active cycle as I thought with the hotter temperatures involved meant it was more of a passive operation?
Any thoughts please?
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Happy to be corrected, but my understanding is that the GPF fitted to TSI engines is essentially a small first stage catalytic convertor which sits next to the turbo and because of the far higher exhaust manifold temps on a petrol engine is effective pretty much immediately after starting so I would doubt that it would ever need to regen in the way a DPF does.
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Happy to be corrected, but my understanding is that the GPF fitted to TSI engines is essentially a small first stage catalytic convertor which sits next to the turbo and because of the far higher exhaust manifold temps on a petrol engine is effective pretty much immediately after starting so I would doubt that it would ever need to regen in the way a DPF does.
….thanks, this is exactly what my understanding was but I can't ignore that it does seem to be doing a regen of some sort, very rarely but I'm sure it is! :undecided:
I'll have to do some digging on google later tonight, as we know the internet's never wrong! :laugh:
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Some forum members over on uk-polos.net with GPF equipped Polo GTI’s / GTI+’s have reported experiencing active / forced GPF regenerations (Polo GTI / GTI+ has a 2.0 EA888 gen 3b engine). Owners have noticed some or all of the following while the regen was happening;
- change in exhaust note
- Sluggish / hesitant engine performance
- increased fuel consumption
- burning smell
- cooling fan running
Seems to be the cars that are used on quite a high proportion of shorter journeys where owners have noticed the active / forced GPF regenerations.
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They don't actively regen AFAIK because petrol exhaust temps are high enough.
They DO however suffer the same as oil burners in so far as it is possible to drive them insufficiently to successfully burn off the soot and clean the filter.
Cars with a GPF have a warning light that says "either you go do some proper driving or you'll need a new filter".
Have a look in your manual at the warning light section...
Its only been a few months since people have had GPF's but already there are stories of people wondering what the light means and probably not much longer before some of them are moaning in the Daily Mail about it costing them money...
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hmm.... conflicting info all over the place!
During the week I am doing pretty much nothing but very short journeys and then try and find excuses to stretch her legs at the weekends but I have never really noticed any other symptoms, just the definite change in exhaust note, and especially no sign of any warning lights regarding it?!?!?
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Can’t say I’ve noticed any evidence of the GPF on mine, except for beautifully clean pipes at all times!
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Can’t say I’ve noticed any evidence of the GPF on mine, except for beautifully clean pipes at all times!
I have to admit, that is the one very nice advantage of the GPF's!
It doesn't really matter to me if it does an active cycle or not because besides the additional exhaust noise you can't really tell, I just thought it was a more passive thing because of the hotter temperatures and I was curious!
Plus I can tell the missus that I HAVE to go and drive round and not just to the shops for her! :laugh:
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There is a new(ish) Bypass a couple of miles from me that has been well used over the 12 months since I picked it up for that very reason
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We have a pre WLTP (no GPF) Polo GTI+ and a WLTP GTI+ (with GPF) in the household and the difference between the 2 is quite pronounced. The one without feels a good 10% more powerful, is slightly more economical and the exhaust note is much better. The one with GPF is far flatter in the midrange.
My wife's hit 4k miles and had an active regen session (not prompted with a warning light, it just happened on her 8 mile journey to work and 8 miles home. She works 7am to 2:30pm, so there's no traffic, and the oil is in excess of 90C within 4 miles, so exhaust should be plenty hot to burn soot passively. For the day that the car was actively regenning, her usual 30mpg was 20mpg. I never saw a 33% drop in fuel economy when any of my 4 DPF equipped TDI Golfs and Sciroccos were actively regenning. Boomier exhaust and abysmal fuel economy, but no higher idling revs.
Other people on the Polo forum also had active regens at about 4k miles, some of them only doing 3 or 4 miles each way a day on their commute. Makes me think that the GPF regen happened by way of scheduling at 4k miles rather than by the car deciding it was required due to level of soot loading.
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Can't say I've noticed any difference in mine since purchase.
So far done 5k miles, mostly minimum of 10 miles but many longer.
I read up as extensively as I could before buying mine and from my research the GPF doesn't really have an active cycle, nothing is injected like a DPF. The soot it burnt off by ensuring an oxygen rich environment where it self ignites, the oxygen rich environment is created each time the car is on a trailing throttle and if that isn't sufficient to burn soot out of the GPF the engine management system retards the ignition timing to help create one.
I seem to recall my reading on the subject was based on some Mercedes Benz info found on the internet.
I was thinking of running something like obd11 to see if I could see anything happening but I've not done that yet.
All my DPF equipt cars I run torque app or similar which mostly tells me the dpf temperature but I believe there are no external measuring probes fitted to a GPF system
If some one reading this knows how best to monitor the GPF please let us know.
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Ok, not many people reporting active GPF/OPF regeneration with their performance Golfs, but pretty much everyone reporting experiencing their first one with their Polo GTI is doing so at around 4k miles. Maybe there's a "just in case" cycle programmed in for the Polo's EA888 3b variant engine that isn't present on the Golf's EA888 3 variant? Perhaps as a result of the audi valve-lift tech on the inlet and use of Budack-cycle for greater economy under low load?
From what I have read, petrol cars generally run with a stoichiometrically correct fuel:air mix (just the right ratio, no sizeable excess of air), so injecting fuel into the exhaust system is a waste of time because there is almost no oxygen in the exhaust gas to ignite it. The petrol exhaust is up to temp (in excess of 550C) in a matter of a few miles due to petrol engines chucking so much of the engine's output away in the exhaust (diesels are more economical because more energy released in ignition is converted into kinetic energy that the drivetrain can make use of).
So after 2 miles from cold, the petrol engine has the fuel source (the soot), the heat, but not necessarily the oxygen (ever heard of the combustion triangle in Chemistry lessons?). By comparison, diesels have the oxygen, the fuel (soot), but not necessarily the heat on shorter journeys, necessitating ignition of fuel in the exhaust system to raise the temp during an active or forced regen.
Excess oxygen in the exhaust of a petrol engine comes from engine braking ("motoring the engine"), as the engine under no load requires no fuel and just compresses air to get rid through the exhaust while doing so.
It seems to me then, a lack of ideal conditions to passively combust soot collected in a GPF/OPF is down to the driver never easing off the accelerator to allow oxygen rich air into the exhaust. So you could blame it on driving style if someone is either on the accelerator or brake, never letting the car slow down under no load.
I could quite easily believe this of my wife's driving style- she brakes a lot more than me, and her car always runs a bit better after I've had it.
Some of the blame could also be attributed to everyone having a DSG box now. Running in auto mode, engine braking is negligible, the engine always seems to be getting some fuel even when you've come off the accelerator because the rate of deceleration in any particular gear with no throttle input seems much less with DSG than with a manual box.
There's definitely something happening with GPF/OPF equipped cars to forcibly clear the load as it builds up. My guess is it combusts under low fuel concentration and an oxygen excess so that some oxygen is available to the exhaust. I found the mpg drop unbelievable 1/3 drop in fuel economy for 2 x 8 mile journeys.
I prefer my Polo GTI+ without GPF to the wife's with GPF.
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We have a pre WLTP (no GPF) Polo GTI+ and a WLTP GTI+ (with GPF) in the household and the difference between the 2 is quite pronounced. The one without feels a good 10% more powerful, is slightly more economical and the exhaust note is much better. The one with GPF is far flatter in the midrange.
Interesting - have you watched the Carwow video of the pre WTLP RS3 vs post WTLP RS3? Worth a watch as includes dyno runs. They make their power in different places.
https://youtu.be/pACT2SUBI_c
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We have a pre WLTP (no GPF) Polo GTI+ and a WLTP GTI+ (with GPF) in the household and the difference between the 2 is quite pronounced. The one without feels a good 10% more powerful, is slightly more economical and the exhaust note is much better. The one with GPF is far flatter in the midrange.
Interesting - have you watched the Carwow video of the pre WTLP RS3 vs post WTLP RS3? Worth a watch as includes dyno runs. They make their power in different places.
https://youtu.be/pACT2SUBI_c
Just watched it. I see a bit of that between the 2 Polos. My pre WLTP one is significantly better in the mid range. In the lower end, in lower gears (like pulling away, to 20mph), the throttle response seems livelier on the post WLTP one, but it doesn't feel any quicker there (almost like a pedalbox effect - less press for same response). Top end? There doesn't seem much between the 2.
I don't have a dyno, but I do a rolling start between 2 signs on a local dual carriageway to assess differences, from 20mph.
My R reached 98mph when passing the second marker, my MK7 GTD reached 81mph stock and 86mph with a DTUK box on. My 2018 Polo GTI+ manages 85mph and the wife's 2019 model (with GPF) manages 83mph.
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So, it looks like they try to tune out the resulting restriction as evenly as possible across the rev range, which is what you might expect, I guess. Maybe another thing that would be different for an engine designed to have a GPF from the getgo.
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When they introduced dpf with euro 5 the difference was quite noticeable. I had two identical cars back to back and the euro 5 was noticeably down on power. These particle filters are a restriction on the exhaust, everyone knows that has an effect. However it's the way of the world and what's gone is gone.
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
A very interesting document, thanks for the posting.
So it seems an active cycle is every 2000kms, can't say I've noticed mine being done, I guess that's a good thing
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So it seems an active cycle is every 2000kms, can't say I've noticed mine being done, I guess that's a good thing
As someone who's had a lot of Euro 6 oil burners... most of the time you don't notice the DPF regens. Sometimes you do.
A GPF is much smaller than a DPF so I'd guess the regen is much quicker, so chances of you spotting it doing it are minimal I'd guess.
The main thing I spot with a DPF regen is either the fan raging after I park up (when the weather is not blazing hot) or at traffic lights when the idle revs are 1k more than normal tickover and start-stop won't kick in despite all of the other conditions being met.
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
A very interesting document, thanks for the posting.
So it seems an active cycle is every 2000kms, can't say I've noticed mine being done, I guess that's a good thing
I knew it was doing a regen of some sort!! It is very subtle and is nothing more than a slight increase in exhaust volume in my case, with the stereo on I doubt you'd even notice it, no rough idle, no loss of performance for day to day driving or any warning lights as suggested early!!
I would like to just say before the sound of regen cycles start scaring folks, I've had my GTI for about 6 months and it has only done it twice in that time but I put it massively down to my very short work commute, at less than 1 mile I'm guessing this is way from the norm and yes I could walk but I work hard to have a nice car and I'm going to bloody well use it!!! plus it does sound lovely on cold start in the morning! :laugh:
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
btw - thank you topher, this may well finally answer my original post! :shocked:
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any warning lights as suggested early!!
The warning light will be there.... because there are still conditions under which the regen doesn't happen and the filter gets dangerously full...
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
A very interesting document, thanks for the posting.
So it seems an active cycle is every 2000kms, can't say I've noticed mine being done, I guess that's a good thing
I knew it was doing a regen of some sort!! It is very subtle and is nothing more than a slight increase in exhaust volume in my case, with the stereo on I doubt you'd even notice it, no rough idle, no loss of performance for day to day driving or any warning lights as suggested early!!
I would like to just say before the sound of regen cycles start scaring folks, I've had my GTI for about 6 months and it has only done it twice in that time but I put it massively down to my very short work commute, at less than 1 mile I'm guessing this is way from the norm and yes I could walk but I work hard to have a nice car and I'm going to bloody well use it!!! plus it does sound lovely on cold start in the morning! :laugh:
My Wife's Polo GTI+ has done it just the once, at about 4k miles, and the 33% drop in mpg really stood out. Perhaps with your 1 mile commute, mpg is never a consideration for you as you know it'll be rock bottom when the coolant in your car may not even reach 50C by the time you get to work. There was no warning light when the Polo was doing it's very noticeable regen.
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
A very interesting document, thanks for the posting.
So it seems an active cycle is every 2000kms, can't say I've noticed mine being done, I guess that's a good thing
I knew it was doing a regen of some sort!! It is very subtle and is nothing more than a slight increase in exhaust volume in my case, with the stereo on I doubt you'd even notice it, no rough idle, no loss of performance for day to day driving or any warning lights as suggested early!!
I would like to just say before the sound of regen cycles start scaring folks, I've had my GTI for about 6 months and it has only done it twice in that time but I put it massively down to my very short work commute, at less than 1 mile I'm guessing this is way from the norm and yes I could walk but I work hard to have a nice car and I'm going to bloody well use it!!! plus it does sound lovely on cold start in the morning! :laugh:
My Wife's Polo GTI+ has done it just the once, at about 4k miles, and the 33% drop in mpg really stood out. Perhaps with your 1 mile commute, mpg is never a consideration for you as you know it'll be rock bottom when the coolant in your car may not even reach 50C by the time you get to work. There was no warning light when the Polo was doing it's very noticeable regen.
Reckon mine has probably done it a few times but wasn't really aware it. Just done over 12k miles since it was new June '18 and lots of short commutes recently since we moved - 3-4 miles to the office depending on the route.
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I'm still not 100% convinced that my May 2018 (built Apr 18) non PP GTI even has a GPF, even though there is no soot whatsoever on the tail pipes (nor has there ever been). It was my understanding that was one of the reasons why they dropped the 230ps GTI in favour of just the 245ps GTI PP, as just the PP gained the GPF, and that these didn't come on stream until mid 2018.
Is there anyway to definitely check as I've seen photos on the underside where people claim that the front most box (just aft of the crossmember) is the GPF, but I was told that's actually the catalytic converter and that a GPF is actually formed as part of the exhaust manifold near the turbo to get it super hot really quickly.
I must pop the bonnet on mine and have a look around.
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I'm still not 100% convinced that my May 2018 (built Apr 18) non PP GTI even has a GPF, even though there is no soot whatsoever on the tail pipes (nor has there ever been). It was my understanding that was one of the reasons why they dropped the 230ps GTI in favour of just the 245ps GTI PP, as just the PP gained the GPF, and that these didn't come on stream until mid 2018.
Is there anyway to definitely check as I've seen photos on the underside where people claim that the front most box (just aft of the crossmember) is the GPF, but I was told that's actually the catalytic converter and that a GPF is actually formed as part of the exhaust manifold near the turbo to get it super hot really quickly.
I must pop the bonnet on mine and have a look around.
I had a facelift 2017 230ps DSG which farted and sooted up the tailpipes after only a week or so of driving. Guess if yours are soot-free then maybe has one.
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as with DPF systems, the GPF will actively regenerate when it needs to. Search for the self study program "SSP 558" if you want to learn more. https://procarmanuals.com/vag-ssp-558-close-coupled-petrol-particulate-filter/
A very interesting document, thanks for the posting.
So it seems an active cycle is every 2000kms, can't say I've noticed mine being done, I guess that's a good thing
I knew it was doing a regen of some sort!! It is very subtle and is nothing more than a slight increase in exhaust volume in my case, with the stereo on I doubt you'd even notice it, no rough idle, no loss of performance for day to day driving or any warning lights as suggested early!!
I would like to just say before the sound of regen cycles start scaring folks, I've had my GTI for about 6 months and it has only done it twice in that time but I put it massively down to my very short work commute, at less than 1 mile I'm guessing this is way from the norm and yes I could walk but I work hard to have a nice car and I'm going to bloody well use it!!! plus it does sound lovely on cold start in the morning! :laugh:
My Wife's Polo GTI+ has done it just the once, at about 4k miles, and the 33% drop in mpg really stood out. Perhaps with your 1 mile commute, mpg is never a consideration for you as you know it'll be rock bottom when the coolant in your car may not even reach 50C by the time you get to work. There was no warning light when the Polo was doing it's very noticeable regen.
I'm surprised you can see such a significant fuel decrease as from what I understand no additional fuel is used to regenerate these petrol filters......the above posted vw document doesn't actually say how it regenerates but I did read on a Mercedes document that basically said the timing is retarded to generate an oxygen rich atmosphere to allow combustion to take place.
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I had a facelift 2017 230ps DSG which farted and sooted up the tailpipes after only a week or so of driving. Guess if yours are soot-free then maybe has one.
Well I had a look under the bonnet at lunchtime, but because of the shrouding around the turbo, I couldn't really see much. Guess the only way to have a real look is with the car up on ramps ?
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I had a facelift 2017 230ps DSG which farted and sooted up the tailpipes after only a week or so of driving. Guess if yours are soot-free then maybe has one.
Well I had a look under the bonnet at lunchtime, but because of the shrouding around the turbo, I couldn't really see much. Guess the only way to have a real look is with the car up on ramps ?
To me it sounds like you have a GPF if you always have clean exhausts! and am I correct in thinking the loss of DSG farts was purely because of the GPFs?!? but I'm guessing your in a manual Sootchucker? :undecided:
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Short of DSG Sootchucker, that's a hell of a spec list on yours!! :shocked:
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I'm surprised you can see such a significant fuel decrease as from what I understand no additional fuel is used to regenerate these petrol filters......the above posted vw document doesn't actually say how it regenerates but I did read on a Mercedes document that basically said the timing is retarded to generate an oxygen rich atmosphere to allow combustion to take place.
I'm surprised too. It seems to defy everything I think I know about GPF regen. I can't see why the car would want to run so rich as to cause a 33% drop in fuel economy while regenerating without a warning light on the dash. Maybe it was running mainly in port injection mode rather than DI mode (Polo GTI still has dual fuelling) and trying to get hot quicker with a rich mix? Doesn't make any sense to me as a petrol exhaust (and therefore GPF) gets hot plenty quick anyway.
I can't fathom any reason for such a dive in mpg (temporarily), but the car did it while seemingly regenerating the GPF. Any ideas?
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I had a facelift 2017 230ps DSG which farted and sooted up the tailpipes after only a week or so of driving. Guess if yours are soot-free then maybe has one.
Well I had a look under the bonnet at lunchtime, but because of the shrouding around the turbo, I couldn't really see much. Guess the only way to have a real look is with the car up on ramps ?
If you have spotlessly clean exhaust tips and not as a result of a meticulous cleaning regime, I'm almost certain you'll have a GPF. Are you still doing huge mileage? If so then (unlikely), your exhaust is hot enough for long enough to be burning the soot off your exhaust - can't imagine the tips getting up to 550-600C to make this happen though.
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Short of DSG Sootchucker, that's a hell of a spec list on yours!!
Ahem..cough...it is DSG ;D
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If you have spotlessly clean exhaust tips and not as a result of a meticulous cleaning regime, I'm almost certain you'll have a GPF. Are you still doing huge mileage? If so then (unlikely), your exhaust is hot enough for long enough to be burning the soot off your exhaust - can't imagine the tips getting up to 550-600C to make this happen though.
Nah...I'm only doing just over 7k miles a year which is why I changed from the GTD to the GTI
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My 7.5 19 R revs higher on cold start and for longer than my 7 R 64 plate. I have also turned it off at home and thought why is the fan going. I do use sport mode manual downshifts all the time though to let the car slow down. The popping is addictive.
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Short of DSG Sootchucker, that's a hell of a spec list on yours!!
Ahem..cough...it is DSG ;D
:embarrassed: Oops.... I may have missed that :embarrassed:
So was there any option box you didn't tick?!?! :laugh: