Hello,

I would like to ask for your help. I have two different engine. DFGA and CXXB. 2.0 liter with adblue and 1.6 liter without adblue. The oil ash mass quantity is:

• DFGA - 60g

• CXXB - 11g

The ash mass limit is 80g.

Both cars have the same mileage and are used in the same way. Why is there such a big difference between the two numbers? Is 60g a lot? How effective is DPF cleaning? I'm not talking about regeneration.

Thank you!

Edited 21 hours ago21 hr by fdani

Which engine has the lower ash count - the 2.0 litre Adblu one?

I'd think 60g is fairly high, but I guess it depends on how long it will take to add the remaining 20g.

Does the DFGA engine use/burn more oil than the CXXB?

1 minute ago, Warrior193 said:

Which engine has the lower ash count - the 2.0 litre Adblu one?

I'd think 60g is fairly high, but I guess it depends on how long it will take to add the remaining 20g.

Hello,

The 1.6-litre engine has a lower ash content.

2 minutes ago, Breezy_Pete said:

Does the DFGA engine use/burn more oil than the CXXB?

The cxxb doesn’t use up the oil; as for the dfga, I’m not sure. I haven’t used the dfga much yet.

Edited 19 hours ago19 hr by fdani

I predict that you will find that the DFGA needs topping up with oil between services.

DPF ash load primarily depends on mileage and the number of regens. While it is possible that on EU6 engines it is measured / derived from DPF pressure loss after regen (doubt it), at least on our 2012 Roomster's EU5 1.6TDI CAYC 105bhp engine the ash load is simply calculated and increased based on mileage and number of regens, no measurements involved. If you experience frequent regens, you will find ash load going up quickly even though there is no change in pressure readings around DPF, i.e. no actual ash.

4 hours ago, dieselV6 said:

DPF ash load primarily depends on mileage and the number of regens. While it is possible that on EU6 engines it is measured / derived from DPF pressure loss after regen (doubt it), at least on our 2012 Roomster's EU5 1.6TDI CAYC 105bhp engine the ash load is simply calculated and increased based on mileage and number of regens, no measurements involved. If you experience frequent regens, you will find ash load going up quickly even though there is no change in pressure readings around DPF, i.e. no actual ash.

Could this 60g be a natural occurrence? The worst-case scenario is that oil gets into the DPF. If the 60 g is a value calculated from the regenerations, it could not have accumulated from the normal regeneration cycles. It is currently regenerating every 350 km.

Not sure what the exact calc for ash loading is, but it involves both number of regens and mileage. What's the mileage on each car/engine? In any case, if there are no signs of restriction in the exhaust (power loss, increased fuel consumption, regen completion issues etc.), the large amount of "accumulated ash mass" is just imaginary, there is far less ash in the DPF in reality. It is just a number / counter in the ECU which by the way can be adapted to a smaller value with VCDS, at least on earlier engines like CAYC. I honestly think that ash number was just put there to cover backside in case of clogged DPFs over the car's life, and also to force replacing DPFs latest at a certain mileage / after certain number of regens or both. The correct way to evaluate amount of ash would be to measure and average pressure loss after completion of each regen and indicate that DPF pressure loss post regen is getting on the high side, but my guess is that given varying temperatures and gas flow, the exhaust sensors used for it are either not accurate or not reliable enough, especially after many years of use / high mileage.

Edited 7 hours ago7 hr by dieselV6

13 minutes ago, dieselV6 said:

Not sure what the exact calc for ash loading is, but it involves both number of regens and mileage. What's the mileage on each car/engine? In any case, if there are no signs of restriction in the exhaust (power loss, increased fuel consumption, regen completion issues etc.), the large amount of "accumulated ash" is just imaginary, there is far less ash in reality, it is just a number in the ECU which by the way can be adapted to a smaller value with VCDS, at least on earlier engines like CAYC. I honestly think that ash number was just put there to cover backside in case of clogged DPFs over the car's life, and also to force replacing DPFs at most at a certain mileage. The correct way to evaluate amount of ash would be to measure and average pressure loss after completion of each regen, but my guess is that given varying temperatures and gas flow, the exhaust sensors used for it are either not accurate or not reliable enough, especially after many years of use / high mileage.

I managed to obtain data from two 2.0-litre engines. 181000km - 55g and 130000km - 47g. The CXXB is now the main suspect.

Again, you might be chasing ghosts, at least on CAYC one will for sure end up with ash mass measurement exceeding limit after enough mileage and regens even if the DPF is empty of ash altogether, it is just a calculation in the ECU that does not take into account DPF pressure measurements at all.

Or in other words, if you make a 300 regens and drive 100k km, the calc could be e.g. num regens x 0.1g + num kkm * 0.3g (I pulled numbers out of thin air, just like the calc in your car's ECU) resulting in 60g ash mass "measurement" even if in reality there would be only 15g-20g ash in the DPF at that point. Conversely, if you use poor quality, ash generating oil or if the engine burns a lot of oil, you may find clogged DPF while the ECU's "ash mass measurement" shows 20g or less, as in fact quite a few people have experienced.

May I ask why you are chasing after this number? Are there any other issues with the engine to even be looking at ash mass?

Just to chime in, my car 2014 Vrs 2.0 Tdi CUPA engine, manual gearbox, has 248kkm now and OBD11 shows oil ash mass 57g with the limit being also 80g.

My car uses about 1,5dl of oil per 1000km, has been like this for the last 100kkm. Only used 5W30 oil.

The engine has good power and i can get 5-5,3 liters/100km consumption with 225/40/18 tyres in the summer with speeds of 100-120kmh.

4 hours ago, dieselV6 said:

Again, you might be chasing ghosts, at least on CAYC one will for sure end up with ash mass measurement exceeding limit after enough mileage and regens even if the DPF is empty of ash altogether, it is just a calculation in the ECU that does not take into account DPF pressure measurements at all.

Or in other words, if you make a 300 regens and drive 100k km, the calc could be e.g. num regens x 0.1g + num kkm * 0.3g (I pulled numbers out of thin air, just like the calc in your car's ECU) resulting in 60g ash mass "measurement" even if in reality there would be only 15g-20g ash in the DPF at that point. Conversely, if you use poor quality, ash generating oil or if the engine burns a lot of oil, you may find clogged DPF while the ECU's "ash mass measurement" shows 20g or less, as in fact quite a few people have experienced.

May I ask why you are chasing after this number? Are there any other issues with the engine to even be looking at ash mass?

This is the quickest way I can access this data using VCDS. In theory, it should reflect the actual condition, but I’m not entirely sure whether I’m correct.

This is exactly what I am trying to say, the "accumulated ash mass" is just VW's / ECU's theory. In practice, actual DPF condition is OK until clogged enough to cause backpressure and related loss of performance and problems with completing regen or frequent regens. Can be well before 80g, can also be way after 80g. I stress that this is certainly the case for EU5 engines, perhaps EU6 ones have better pressure monitoring, but I doubt it. The only way to be sure would be to swap the DPF without resetting ECU, drive for a while and look at the accumulated ash mass reading sometime afterwards. On EU5 TDI, for sure the ECU would not notice new DPF and just keep increasing accumulated ash value in line with mileage / number of regens. I suspect it is the same for EU6 TDIs, but not 100% sure.