GPF active cycles?

[dean5125]

Hi all,

Hope you all had a good xmas and new year?

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?

[Philip]

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.

[dean5125]

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!

I'll have to do some digging on google later tonight, as we know the internet's never wrong!

[SRGTD]

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.

[fredgroves]

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...

[dean5125]

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?!?!?

[Talk-torque]

Can’t say I’ve noticed any evidence of the GPF on mine, except for beautifully clean pipes at all times!

[dean5125]

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!
 

[Adam T7]

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

[monkeyhanger]

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.