Cayman 718 GPF Failure

[Cyclemotor1958]

Hi Guys& Girls

Without prejudice

Following on from my last post regarding exhaust back pressure on our GPF filters.

Found this on YouTube, it shows you the function of the differential pressure sensor and how important this sensor and its readings are to the emission device on our cars.

See link below.

I know I go on about checking for back pressure when these cars are reporting the 100% oil ash load, and the need to change the filter.

But if the differential pressure sensor information is correct, and reading are very low, then we have the answer.

Normally if a filter is starting to get quite blocked, you would see a reading at tickover between say 10 to 100 HPA.

If you increase the revs to between 2.5 and 3K you may see 250 to 300 HPA.

In the last 2 days I have seen sensor readings no higher than 4.0 HPA convert this to PSI and you get 0.058 PSI.

I have said many times that the data we are seeing on these GPF filter reports page 42, make no sense at all.

Yet the dealers and Porsche seem to be ignoring the wrong information that's recorded on their report, and it's been the same on all the GPF reports I have seen over the last year.

Let's use the information we have and start looking at the real issue.

We have Cars that had filters fitted last year, that already have high oil ash % figures recorded and they will be going back into the dealers for them to have another look at this problem.

We could save Porsche alot of money if we check the actual back pressure before the exhaust are removed.

Sorry to go on again

Dave

 

[Paul-718gts]

Well as you know Dave my car is back in next week for further investigation work following its first VAL check that showed a reading of 27% Ash after 500 miles of driving with a new filter being fitted under warranty along with a new sensor.

I believe at the time my car may have been the only one that had both parts fitted at the same time ?

I must say the Principal at the dealership has been very supportive, along with his team of Gold techs.

With the additional tests and questions that we have requested hopefully this will help find the root cause we are all seeking.

Let’s hope we can use this as an opportunity to finally find a solution to this ongoing issue.

 

[Cyclemotor1958]

Morning Paul,
Looking forward to getting some positive results and explanations, fingers crossed.
Have a good weekend, catchup soon
Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Without prejudice

Two more 718 drivers contacted me over the weekend with GPF issues asking for advice.

Both had the usual oil ash loading at 100%, and the GPF needs replacing.

Usually when your filter gets to 100% and the warning light comes on, you will be told the GPF needs replacing because its blocked with ash.

What you are not told is that something doesn't seem right with the differential pressure sensor reading that monitors the pressure in your GPF.

It looks very very low.

Well, it could be a faulty sensor.

Let's manually check the pressure in the GPF which will confirm the sensor reading is accurate.

Good idea, worth a look

A differential pressure sensor reading of 6.25 hPa was sent to me last week on a GPF filter that was showing the usual 100 % oil ash loading.

If you convert 6.25 hPa to PSI you get 0.09 PSI.

So no pressure at all

Why are we not looking at this in more detail.

It's been the same on all the cars I have been involved with, that required new filters, and its continuing to be the same on these cars going forward into this year.

Just a thought

Kind Regards

Dave

 

[JohnCRS]

A (non) update. So far the club has not been able to get any answers from Porsche GB or Gmbh on this issue. We are now focussing on simply trying to get a technical representative to read this thread, or at least the later pages, and to comment on what is going on. If we can achieve that we have somethiing to work from.

 

[Paul-718gts]

A (non) update. So far the club has not been able to get any answers from Porsche GB or Gmbh on this issue. We are now focussing on simply trying to get a technical representative to read this thread, or at least the later pages, and to comment on what is going on. If we can achieve that we have somethiing to work from.

Hi John,
Disappointing to say the least that the owners club sounds like it has no leverage with the Brand given the number of loyal supports that are members.
As we haven’t seen anything in the monthly mag for a few editions apart from a very small paragraph, why don’t we look at a double page spread in next months, I am sure David is more than capable of writing a very factual article that would grab the attention of the brand if that is what the club are trying to achieve?
You could even ask for some of those effected by this situation to add their journey so far to give David’s article some real world credibility.

More than happy to donate my copy to a local dealership service area for customers to read that maybe are not enthusiasts and purely buy based on the brand recognition/kudos created by us the brand sponsor’s..

Surely it’s got to be better for the club to go to press with an article on this matter rather than another non brand mag ?

My understanding is that this post is up to over 30k views… must be the biggest story in years.

 

[Scrounger]

I’ve said this more than once and I’ll say it again. Go to the motoring press.

It’s all well and good saying this is happening and this is wrong but if you go down the supposedly official route and get no response the only other option is to highlight it to the masses. They’ll have no option but to take notice and respond as it’s potentially damaging to the brand and to the users pocket if it continues.

It just needs someone to talk to the likes of Auto Express to start the ball rolling.

Dan.

 

[Cyclemotor1958]

Hi Guys & Girls

Without prejudice

Following on from my last post and our focus on the technical GPF details on these cars, found this information regarding our oil ash issue.

What makes this information interesting is the mention of the oil ash load as a calculated reading.

We have never seen in the calculated reading K230 any recorded information at all.

Its always been recorded in the K231 section of the report, and when it gets to 100%, the light comes on and we have a problem.

This information is from the Porsche PIWIS coding information, found in the ENGINE OVER REV REPORT, ATTACHMENTS.

It clearly shows the Particle filter calculated oil ash load.
With an instruction to select values F12.
It also mentions the soot load.

This is very interesting and we need to look into this in more detail.

We currently have a vehicle in with a Porsche Dealer at the moment and we will be suggesting they check this out.

Enclose a GPF report showing the oil ash readings in detail, and the coding information I found.

Looking forward to next weeks investigations.
Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Had a chap contact me from the 718 forum concerning the GPF report I sent out regarding the oil ash reading.
This is my reply

Without prejudice

The GPF report I sent you shows a 100% oil ash reading, remember this reading doesn't mean the GPF is blocked, infact all the ones we have checked the back pressure on, had no real pressure at all.

Given the average mileage these vehicles have covered it's what you would normally see, a simple check to see if your filter is dealing with the soot is to check your rear exhaust tips.
You should find a light grey deposit with a slight brown tint, which is the burnt ash, no soot.

If you look at my previous post, and the information I found concerning the oil ash reference as a calculation in the coding section of the over rev section on the PIWIS tester, this is something to investigate.

I would expect any instruction from the ECU that puts a warning light on the dashboard, to come from a calculated value, not a measured value, as you can see on the GPF report.
It seems to me it's the wrong way round, a measured value can increase and decrease.

The main problem is we can not rely on this information from the GPF report as its based on an algorithm that is incorrect and the only actual reading it giving is the differential pressure current sensor reading.

All the rest are either measured or calculated, and sometimes we find 0.00 readings are found were you wouldn't expect them to be.

Yet when a GPF filter is condemned, the differential pressure sensor reading is not looked at and acted on.

We will get to the bottom of this, with or without Porsche Technicals help, it's a shame we could not work together, after all it's their problem, and their customers who are suffering and losing patience with them and the brand.

Bye for now

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Without prejudice

Just found this on YouTube, this is what we need, re setting a DPF filters values.

Regards
Dave

 

[Cyclemotor1958]

Morning Guys & Girls

Without prejudice

Sorry it's me again, another Cayman driver contacted
me yesterday with the usual P242F oil ash load DTC.

I have put together this short diagnostic check below,
to check for back pressure and possible differential pressure sensor faults.

You need a manometer set to hPa to measure this pressure reading, it can be purchased on Amazon for around £50 to £60.

This same manometer can be used to check your AOS vacuum readings, you just need to buy a oil filler cap, to connect the two.
The readings for the AOS are measured in inH20,(inches of water).

My test info.

Look at the GPF report page 42 of the Vehicle Analysis Log

Check the oil ash measured K231 value, it's usually at 100% if the engine light and warning message is on the dashboard.

Check both soot load values, K221 & K230, they usually have either no values or just very low soot load values.

Check K251 differential pressure sensor current value, if low, which it usually is, carry out these checks below.

Go to the differential pressure sensor and remove both rubber pipes, make sure these are not blocked with soot.

If OK, you then start up the engine, connect a manometer to the larger supply pipe and check the actual exhaust back pressure in hPa, from the GPF.

You then compare the manual and diagnostic readings from your diagnostic tester with the car running.

This then confirms the sensor is either working correctly or not.

If all is OK, and no significant back pressure is seen, then this proves that the GPF filter is not blocked with ash.

This also confirms that the filter is not blocked with soot.

I have sent this information out to 5 owners this morning in a hope that we can get some valuable information back to backup our suspicions that these GPF filters are not faulty.

Will keep you informed

Regards
Dave