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More exhaust temperatures available?

Posted: Sat May 01, 2021 3:28 pm
by Piotre22

First of all: the app is great!

I am opening a topic here because it would be interesting to have more temperatures available. Especially the temperature before the Oxidation Catalyst would be interesting because there you can see the temperature increase of the exothermic reaction which takes place in the oxidation catalyst.

The fuel which is injected by the late post injections 2 and 3 does not burn in the engine. The unburned fuel then comes to the Oxidation catalyst, which is just before the DPF. In the Oxidation catalyst the unburned fuel is "burned" by a catalytic exothermic reaction. With that reaction the temperature is high enough for a active DPF Regeneration.

I just created a diagram of a DPF regeneration with a measurement of the OBD temperatures with the Torque App.

Here you can see what is happening

Lets take for example t = 2250s

Temperature upstream turbine (red) = 525°C
Temperature downstream turbine = Temperature upstream Oxidation catalyst (blue) = 475°C
Temperature downstream Oxidation Catalyst = upstream DPF (magenta) = 620 °C =>> Temperature increase of 145°C (!!!)
Temperature downstream DPF (green) = 520 °C

It would be very interesting if these additional temperatures would be available in the app.

best regards,

P.s.: Air fuel ratio would also be interesting

Re: More exhaust temperatures available?

Posted: Mon May 03, 2021 10:46 am
by admin
Interesting topic!

What's your engine type?

I know the regeneration process and I agree that there are many other parameters useful to understand what the engine is doing, but my main problems are the limited screen size and the differences between every VAG engine.
Unfortunately, VAG doesn't have a standard set of reading parameters, every engine family (and sometimes every single engine) has its own parameters setup and not all sensors are present in all engines. This chaotic world is the worst case by the diagnostic point of view, especially for who tries to collect data with reverse engineering like me.
I could add specific parameters for a single engine group, but I prefer to keep all the parameters as much as possibile the same.
One of my TODO activity is to add some customizable fields in which everyone can set the parameter choosing from a list, but this is a big work that in this period I can't afford.

Re: More exhaust temperatures available?

Posted: Mon May 03, 2021 12:44 pm
by Piotre22
The diagram from above is created with data from a V6 3.0 TDI CRTC/2016, but I do not have this car anymore.
(When I had the CRTC engine I only had the free version of the DPF app, but it worked)

Now I have a 2.0 TDI DETA/2019 and the full DPF app.

I dont know if it helps: The torque App uses the OBD protocol. In the OBD protocol the exhaust temperature names are always the same for almost every engine. There you also have throttle valve position, rail pressure, air fuel ratio, coolant temperature, voltage of the generator, boost pressure and much more…My old V6 3.0 TDI CRTC used the same OBD names as my new 2.0 TDI DETA, even though it is a complete different engine.

So far I know you read the DPF data using CAN protocol. I dont know if it is even possible to read out CAN and OBD protocol at the same time. The specific DPF data you read out is definitely not available in the OBD data, there you have to use CAN.

[Dream mode on]
Optimum would be to have the specific DPF values as soot mass in the torque App, or to have all the other values which i mentioned before in the VAG DPF App :roll: :roll: :roll:
[Dream mode off]

I know that this is big work.


Re: More exhaust temperatures available?

Posted: Mon May 03, 2021 2:10 pm
by Piotre22
With the additional values you can also show some other interesting things which happen at the exhaust aftertreatment system.
Some of the engines also have a LNT (Lean NOx Trap), also known as NSC (NOx Storage Catalyst). It is a combined oxidation catalyst (DOC) and LNT.

Apart from the normal NOx regeneration (DeNOx) with some short rich phases such LNT catalysts also need from time to time a desulfurization (DeSOx). This process needs very high temperatures and a changing air fuel ratio between lean and rich.

Here you can see such a DeSOx process:
My observation was that this DeSOx process is started with a DPF Regeneration with a duration of about 7 minutes, then the DeSOx process (which you can see in the diagram) for about 7 minutes and directly after the DeSOx process another DPF Regeneration of 6 minutes.

This data is also from the V6 3.0 TDI CRTC/2016


Re: More exhaust temperatures available?

Posted: Mon May 03, 2021 2:35 pm
by admin
I have DETA engine too ;)

Yes it would be possibile to read canbus and obd protocol at the same time, but this solve only one of my limits .. the screen size is limited, I'd like to add more useful data, but I had to make a choice to select only the 12 most important values and to keep the app more "usable" for non technical users.
I know that skilled users like you dream to have all of the parameters available ... me too! But in this case the app would be transformed in one of the millions OBD diagnostic app, I preferred to keep the app focused on DPF.

I know the NOx regeneration, I experimented this little regeneration the first time some years ago on a 1.6 TDI, in fact in some engine group (when the value is present) I added the NOx value to make the driver able to understand why the engine starts a regeneration while the soot mass is not high enough.

The additional temperature you'd like to have is another step to go more in depth in the regeneration process, and there are many other parameters we'd like to add, but this requires a big app change, probably a complete redesign of the code.

Just for my knowledge: what the medium distance since your regenerations?

Re: More exhaust temperatures available?

Posted: Mon May 03, 2021 3:51 pm
by Piotre22
Actually I have my new DETA equipped car just for 7 days, at the moment the App says 84%, Soot Mass calc 20g, Soot Mass measured 7g and distance since last regeneration 337 km.

The DETA engine with Euro 6d temp makes a lot of EGR, therefore the regeneration interval is not so long.

My old V6 3.0 TDI CRTC which I had until last week (with standard Euro 6) had sometimes regeneration intervals of more than 1000 km. I think the range was somewhere between 700 and 1300km. But i did not check it so often, because you did not recognize the DPF regeneration during driving. The V6 had no increased idle speed during DPF regeneration, just always standard idle speed of 600 rpm. Only way to recognize: no start/stop (but that could also have other reasons) or running fan after parking the car.
And I only had the free version of the app until last week…

Regarding the additional values:
Maybe it would be a solution if there is a standard setup of the screen (which is sufficient for most users) with the possibility to exchange some values with others?
Some values could also be combined in one field, for example Soot mass calc and measured, time and distance since last regeneration, or Post2 + Post3.
Other way would also be a second page.

Intake throttle valve is for example also an important value during DPF regeneration :)


Re: More exhaust temperatures available?

Posted: Mon May 03, 2021 5:57 pm
by admin
Very new car 8-)

I confirm, this engine heavily uses the 2 EGR valves, in fact in my experience the regenerations occur every about 250-300 km.

Customizable fields is a possibility to add new values as well as a new page, but the big problem for me is to collect similar information from different engines. With a common setup it would be easy, but with dozens of different diagnostic setups (sometimes different also depending on the ECU software version) it's not so easy.
A possible strategy could be to work independently on every single engine group, but this is the contrary of what I did until now.
But I understand that your request, and all other similar request I receive daily, sooner or later will have to be satisfied, somehow.

In the past I tried to read 2 parameters at the same time creating a double value field (it was high and low EGR), but after the implementing I discovered that all the low cost adapters don't accept these kind of request, so I reverted to single data fields adding a new TODO activity for an option to enable double data fields with a specific option in the menu. Line still in the TODO list ...

Honestly I'd love to improve the app with all the request received from the users, but since I'm not a professional developer, almost all of the time I can spend on the app is for error correcting and for replying to emails/forum-messages.
It's a shame because I think the app could be improved a lot giving many more useful information to the user. I'll try to make my best.

Re: More exhaust temperatures available?

Posted: Tue May 04, 2021 7:58 pm
by Piotre22
Thanks for your answer.

Don’t worry! It is perfect that you are open to user suggestions. There are many other apps where this is totally different, most of the times you do not even get an answer at all.

Regarding two values in one field: maybe it is possible to add a small pause so that to values are not requested at the same time? But i am also not a developer…i did a bit Excel VBA and thats all :)

So take your time, and if there will be some updates in the future everybody will be happy :D


Re: More exhaust temperatures available?

Posted: Wed May 05, 2021 8:25 am
by admin
The double value is a different way to request data to the ECU available in the ISO specs.
This single request contains the 2 parameters and the single answer contains the 2 values. It would be a faster way to duplicate the fields available on the screen, losing only some milliseconds due to the slightly bigger data to transmit/receive; on the contrary, sending 2 requests and merging them in the app would duplicate the total request time and I always tried to limit the overall data update time to have more or less a real-time reading.
Following the requests I receive daily to add more information to the app, it's probably time to introduce some new feature and the double data reading is the best and fastest way I think, also because some double data is already present in the internal database because used in an old app version though not used in the last one.