Extreamly slow/long regeneration CAYC, after 100km reg DPF-Light comes also on

[FreshChriss]

Hello,
Second time trying to post here (first post never got approved/disapproved?)
Hopefully this one does because I really need help.


The Situation:
I bought a used VW Golf 6 TDI (CAYC 1.6) about 2-3 months ago.
The car appeared fully functional due to the first 1200Km without problems... presumably because this distance was 98% highway driving (where the output temp was at 407c and it finished the reg in 112Km...).
After this first time, i used the car I'm my normal driving conditions e.g. 2x17km 4 days a week and 2x70Km highway once per week.
I only fuel the car with premium fuel (Shell V-POWER Diesel) (since instantly after purchase) and have switched to high quality oil on the second day of ownership. (The exact fuel and oil works perfectly for years with the 2x Golf 7 2.0 of my parents).
By the way, the car got the vw emission update (around 2018 or so) and i bought it with ecu version 9980 (later updated to 9982 to see if it helps)


The Problem:
After around 400-450km, the active regeneration starts (24g Calculated Soot), which is ok, but it regenerates at a way to low speed of around -109 to -200 mg/km. After exactly 100Km of (continuous) active regeneration, the dpf-lamp lights up and i need to drive another 40-80 km with the light on to get down to 6g Calculated Soot.
This Process has repeated al least 5 times now (and can still be repeated).


Additional Info:
We have no error codes all the time (but error logging generally works on the car)

We replaced the differential pressure sensor, which leaded to smother gas reception on the first 1-5% of the pedal (before the engine was stuttering noticeable when pressing or releasing the first 1-5% of the pedal) so it was likely defect.

The car had around 129500km at the day of the purchase and as we later found out, around 2g of oil ash residue, which we later set to 0 again by mistake due to a miscommunication with the mechanic.

We updated the ecu from version 9980 to 9982 (latest).

The last mechanic I went to had me check the coolant temperature which remains stable at 93-96c when driving. We also did a standing regeneration (which worked without problems but took 35 minutes for 12g calculated to 0g (we didn't measure data during the regeneration)). He also set the value of the oil ash residue to our rough estimate of 35g.


Logs and Data:
I attached a couple of logs (split into different files by me after every change).
I can also provide around 130 Screenshots from the period.
The logs contain driving with and without regeneration.
I also have screen recordings of the last 200Km (of which 140km where regeneration) which i could provide.


Things I have noticed:
During regeneration the dpf input temperature is around 550-650c which is good, but the output temperature seems low with 350-380c?
On the highway I can reach 360c output temp with 400-480c input without active regeneration.
Without the regeneration, the values from the 2 temperatures seem to align to validate each other.
I have read all the (132) posts in the forum and everywhere the output temp is around 500-600c.
Could this be a defect lambda probe not telling the right amount of oxygen to let in, which prevents the soot from burning?


Generally huge thanks for developing the App, it is a godsend in my situation.

Hope you can help me.
Greetings

Chriss

[admin]

Your previous message was probably accidentally discarded inside the tons of spam I receive today. My apologize.

This seems a crazy issue. I've analyzed the logs and everything seems ok but the regeneration speed is extremely slow. I agree with you that the output gas temperature is lower that what I used to see. The best would be to have a confirmation from another CAYC engine about this temperature during the regeneration.
I don't remember similar cases, I've also checked in the mail box but founding nothing that can help.
Did you already ask to the official assistance? At least to identify what can be the defective component.

[FreshChriss]

Hello, thank you for the approval and reply. Too bad to hear that you are affected by spam.

I once found a topic here where a CAYC engine owner posted logs, and another topic where a seat also regenerates longer.

viewtopic.php?f=4&t=3581
viewtopic.php?f=4&t=4511

The CAYC has differences in the ECU (and software) compared to mine, but has higher temps and shorter regen.

I don't quite understand what you mean by "Did you already ask to the official assistance?", do you mean VW directly? The mechanics I've been to have always talked to vw about previous repairs to the car, but there's nothing noticeable there.

I am close to the next regeneration, in the next 2-3 working days. if it is still slow, I will talk to the mechanic and depending on what he says, do another stand regeneration, logging the values (via VCDS) and then try to replace the lambda sensor.

First of all, thank you for your help. If you think of anything else that can help me/what I should check, please post it here. I will keep this thread updated if I get it solved, for potential others who have/get a similar problem.

[admin]

Yes I meant the official VW service guys, just to understand if they already know this kind of issue.
Usually they can also contact the main service office in Germany if there isn't valid solutions to implement. Of course, if you are outside the legal warranty period, you could pay for the service and the solution isn't guaranteed.

Thanks for the updates, your info can be really useful for other users.

[FreshChriss]

Hello again,

one of the repair shops i went to was an official vw repair shop, which also talked to the service office on the phone, but without any helpful findings.

In the meantime, we had the DPF removed and cleaned, and replaced the temperature sensor 4 (behind the DPF) and the EGR valve.

We first tried to replace the temperature sensor individually, but it could not be removed when the vehicle was assembled.

All this unfortunately took a long time, and today the first regeneration after the repair has started. The good news is that it now looks much better and the car has regenerated in a normal time. I have attached the log times, do not be surprised that the records are sometimes so short, I have not run the app on every trip, but at the end of each trip checked the load to know when it is time.

Where I had the DPF cleaned, they have also first looked at the inside (from behind looking at the ceramic). My filter has a crack about 1-2cm large, and had also sooted through itself.

The result of the cleaning is a reduction of the load (soot and ash combined) by 112g and a reduction of the back pressure from 24.3mbar to 10.8mbar.

For cleaning, however, the filter needed 2x 12h at 1000C in the special oven, because after 1x 12h not all soot was burned. Probably the car had no chance with its 600C to burn the filter at all free again, since this had probably clogged with sticky and wet soot, since the previous owner probably always drove only short distances (probably the last 20,000km).

I hope the problem remains fixed and this post helps others with similar problems.

sorry for the long radio silence, but I just had no progress in that time.

Greetings

Chriss

[admin]

Very good news!

Thanks for sharing with us, it will be useful for sure for other users with similar problem.