Help with PIDS & Equations

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Joined: Wed Sep 08, 2021 9:56 pm

Help with PIDS & Equations

Post by IbizaCR140@190 » Wed Sep 08, 2021 11:09 pm


I'd very much appreciate any help with getting a VagDpf PID equation into Torque regards to how VAGDPF calculates EGT or DPF gas temp, I have the values but don't know how VAG DPF works them out there are two bytes I think that correlate to eachother somehow.

For example Soot Mass Calculated on a CFHD engine resides in PID 22114f and an example hex is this:

62114F08EC - 8EC was 2284 in decimal or 22.84g of soot at the time which was nicely displayed in Torque using this equation with 08=A and EC=B: ((A*256)+B)/100
2048+236=2248 then /100 for 22.48
Found that from a captured bluetooth log.

What I need Help with - I have found PID 221044 which is EGT - or DPF input/output gas temp in VAG DPF captured from a bluetooth log.
I cannot seem to work out the multipliers/equation to reach the correct EGT.

This PID is called DPF Surface Temp. (\U00B0C)

It looks like this in the src.

L264 {
Ldc "323231303434"
Ldc "7E805621044"
Ldc -273.1
astore 19
Etc etc.

Two bytes are needed from an example capture of 6210440E8D

The 0E 8D is the EGT. It would be quite warm like 250+ as the first column says 0C when cold and 11 and beyond when hot.

The 8d column slowly ticks down when I turn the engine off as a good example of °C going lower but no equation seems to make sense of the numbers.

How does vag dpf work out the DPF EGT temps from the last two bytes of the value, what's the Equation? You would help me so much if you could tell me please.

For example 21-24°C would be something like 0B69

Or 11 and then 105.

So 11 something 105=21 or 24 I'm not sure but either would be good.

I don't know the correlation to work out the value. It must be in the app code but I can't find it.

Many Thanks

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Posts: 266
Joined: Sun Jun 02, 2019 10:58 pm

Re: Help with PIDS & Equations

Post by admin » Thu Sep 09, 2021 11:17 am

Every parameter has its own formula, ok many of them share the same formula but to understand it I spent many hours/days/weeks in reverse engineering.

Of course this is a core part of the application that I can't share.

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