Hi Guys & Girls
Without Prejudice
Thought we should talk about Ash in GPF filters today, obviously this is causing us some issues at the moment.
Roughly 90% of ash in GPF filters is the product of the combustion of metal additives in the lubricating engine oil being burnt in the engine cylinders.
The rest comes from wear in the engine, additives in the fuel, and incombustibles from the air.
So ash cannot be removed totally by regeneration.
I spend alot of my time researching
the workings of GPF filters and reading data from testing laboratories who are constantly looking at GPF longevity.
There is a condition in the GPF called ASH BRIDGING, this phenomenon causes the walls of the Catalytic area to decrease, which increases the exhaust back pressure.
This then increases the need for more active regenerations to be carried out.
Active regeneration requires a controlled process that is started by the engine control unit. Information from the differential pressure sensor tells the control unit to put on the particulate soot loading light on the dashboard.
Instructing the driver to help in the regeneration of the filter, using deacceleration in the driving cycle.
This is well documented in the drivers manual.
Passive regeneration happens naturally durring high speed driving, with high exhaust temperatures.
The ASH BRIDGING occurs in the GPF filter when the ash particles bond together and block the channels in the filter core.
In my research I found that this testing laboratory injected small amounts of engine oil into the cylinders and measured the affects of the back pressure created in the GPF
They came to the conclusion that small amounts of the extra engine oil added to the crankcase fumes, which is redirected into the cylinders can prematurely increase the ash content in these GPF filters.
We have established 100% that on all of our cars the soot loading light or message has never been seen. So active regeneration on these cars may not be happening as it should do.
If the Dealers and Porsche Technical are right about these filters being blocked 100%, and they have to be replaced.
Then why is it happening again on the cars that have had filters replaced recently.
The ash percentage is increasing quicker over low mileages since replacement.
One of our cars is already at 55 %, and it was fitted this year.
Then it's 100% clear that without active regeneration by the car, these filters will block up prematurely.
Looking back at my first post on this forum on December 14th 2023, I spoke about the affects of what a faulty Air-Oil-Separator can do to these filters.
Durring this last year we have found that none of the dealers involved in our GPF faulty cars, had checked the function of the AOS.
When we asked several of them to check the AOS, they couldn't, because they didn't have a Porsche approved tool.
It's unforgivable that the cost to by this equipment is only around £58.00 including vat.
One dealer even said it would put on the engine light if it failed, so we don't need to check it.
We know from passed experience that when the AOS fails badly, you get lots of white smoke from the exhaust which can be very worrying.
And if you are really unlucky, you can get engine oil sucked into the cylinders which is really bad.
The AOS has no electrical feed back to the ECU, so it's under the radar.
So my question to Porsche Technical and their dealers, why are you not checking their Air-Oil-Separators for excessive vacuum readings.
Hopefully this week we will have a vacuum reading taken from a 718 Cayman thats just had one replaced recently.
We will be able to compare the readings against our readings on file, from lots of cars.
Had another phone call over the weekend, another 718 2019 car with a faulty GPF to sort out.
He should be okay as we have established that his soot light not coming on at all, is clearly a manufacturing defect and should be covered 100%.
And again, when he was sold this car, the sales chap didnt inform him about the emission device fitted to this car, that would require his attention if the warning light came on.
This story is not finished yet, will keep you updated
Dave
