I've got some data, from about 3 or 4 hours of engine running time.
Some of the time the car was stationary for half an hour, the rest of the time it was being driven
I've copied the graphs from Alfa OBD and have got three here to share, from various clogging value ranges.
First graph, is from about 23-25% clogging
DPF 23-25% | Flickr - Photo Sharing!
Second graph from shortly afterwards, idle - motorway run- idle . 24-27% clogging
DPF 24-27% | Flickr - Photo Sharing!
All the other graphs suggest about the same thing, roughly a 5% per hour rise of the clogging value.
The last graph is showing the range of about 39-42% clogging.
DPF 39-42% | Flickr - Photo Sharing!
So, it seems fair to assume that no matter how yoiu drive, there is a timer in the background winding it's way up to an unkown percentage when presumably a regen will occur.
I can see why, if you have a new free flowing dpf , that could be a good feature to have. Prevention is better than cure usually, and so it seems like the engineers sat and had a meeting, and in answer to the question "How often should it do a regen even if there is no other reason to suspect it needs one (pressure ?) ? " and someone seems to have decided that the answer is 'About every 20 hours '.
So the implication of this, contrary to what I thought, is that if you fit a bypass pipe you will still experience regens. Possibly 20 hours of engine running time apart.
So the next question is, if the dpf regen's before 20 hours is up, why does it ? Maybe there is a way for it to detect the need to regen sooner - pressure ? I have had regens occur at much more frequent interval than 20 hours, I would guess even as little as 5 driving hours apart
Also, if it reaches 20 hours and then regens, does it regenerate for the usual length of time as every other regen, or, once the dpf has been brought up to 600 celsius or so, is the pressure measured and the regen cut short if the filter is thought to be clear as a result of a low pressure reading ? The good news here for a bypass pipe user who doesn't get a remap is that although a regen might start, it might also end very quickly)
After that, if the pressure is found to be unusually high, is the 20 hour timer reset to something like 5 hours instead, by preloading it with a 75% clogging value after the end of the last regen ?
I'll have no idea, until I get there !
Any bets on when the regen is going to start, and when it does, how long it will last for ?
I was going to use the 'install a new dpf' routine to reset the clogging value to zero (I think thats what it does anyway !) , but I'm not going to do that just yet. I'll just hold off and wait to see what happens, when, and for how long. I'll also not bother removing/reshaping any more dpf core material because if the dpf flows really well it might not regen at all.
If anyone has AlfaOBD/FES and a dpf in the 90% clogging or more region, do you fancy shortening the wait by taking your laptop for a drive and monitoring the clogging and the regeneration time variables ?
If not, I'll try to do it anyway.....and then sell the information for a fortune MUWAHAHAHA !
PS, I think the 'differential pressure sensor' on AlfaOBD tab 7 (there is a similarly named variable in FES) of my car shows an idle presssure of about 1-3mbar and peaks at around 300mbar when I push the car hard. At a steady 50mph in 6th gear on the flat th epressure is between 20-30mbar, and at 70mph in 6th gear on the flat it reads between 45-60mbar. It just might be interesting to know if anyone else happens to be putting their diagnostic tools on what their pressure reading is too and we can perhaps compare notes and draw some conclusions about using the pressure reading as an indicator of dpf health ?