OK Chris, I have been following this with great interest and it will be a great help down the track in consultation with my mechanic. I will get him to read all this first. Anyway, just some questions which you may well have answered, but are lost in all the info you have provided:
It's about time I did regen of the info (booooo.... bad pun eh ?) Thanks for shining a light at it
1. How do you do the "replace DPF" routine and when should you do it with a normal DPF and a drilled out one?
'replace dpf' is a software function of the laptop application. In AlfaOBD it's located under the 'Active Diagnostic' tab when connected to the engine ECU. In FES it is under tab 'F7 - Adjustments'
When run on AlfaOBD it replied with a 'failed - function not supported' error. However it did complete (I've seen this behaviour with AlfaOBD before). I can't confim that it can be run under the free version of either software. I could try doing it on FES right now but I'm too close to a regen to risk reseting it to zero again
I wouldn't advise anyone runs the routine unless you have anything other than a free flowing dpf or suitable replacement (hollowed out/drilled through/bypass pipe) fitted. The period to the first regen will be very long and if your dpf is already badly clogged it will just be even more so after that time.
It's important to realise though, the 'replace dpf' routine doesn't seem to affect performance in any way. It only affects the time between regens, by reseting it to the longest period required by a new dpf.
One thing I want to try, in time, is to run a 'replace dpf' routine every week and seeing if it stops all regens from taking place. I usually connect up to the car every couple of weeks anyway looking for fault codes (I was doing it because it ran so badly). I would probably reset 'TRIP A' meter and go by driving time...when it gets close to regen time (about 20 hours ?) then it's time to plug in and run the dpf replacement routine again.
2. Are the % clogging figures something the onboard computer on the dash tells you, or is it something your laptop tells you?
Unfortunately, you must have a diagnostic tool to read clogging %. This means that you need a laptop or other mobile device with FES or AlfaOBD on it, and a cheap ELM327 hardware interface to plug the laptop into the car's daignostic socket. Whn I have had my next regen I'll try to confirm that the procedure can be done with the free version of FES (unless someone can confirm it in the meantime) You would need FES or ALfaOBD anyway to check the dpf pressure (if you aren't able to check it be removing the temperature sensor).
3. Has your performance been consistently better since you drilled out the DPF?
It starts of good and stays good, only getting slightly smoother after an ECU reset. There's one of the characvteristic drop off in performance which you would normally feel between regens.
4. Has your mpg been consistently better?
This is also affected by an ECU reset. Until the ECU learns all the new parameters after a reasonable period of driving the mpg is only slightly better, after an hour or two of driving it is much better. i have reset the ECU twice and found the same thing happens. This is normal behaviour which you would find if yoiu did a reset with a healthy dpf in place too
5. Remind me which engine you have.
Late 2008 1.9JTDm 16v (150HP, 110kW).
I believe all of the above is relevant to any engine, where the dpf is located beneath the geartsick and looks like this dpf | Flickr - Photo Sharing!
. I haven't seen a 2.4 dpf, but it sounds like Timbo's 2.4 was the same.
Vauxhall and Saab owners with the same engine/ECU also have the same dpf, and they also drill theirs and report the same effects
6. Once you have collected all your data and come to some conclusions, perhaps you could outline in simple terms what you suggest we do and how to go about it. Naturally we all need to do it at our own risk.
I can do that
I want to see what happens at the next regen first (curiosity more than anything) and then I'll monitor over time with the passing of more regens and see if the interval between regens stays constant and long.
When the dpf is clogged you have a car which is typically described by it's owners as a bit sluggish or heavy. I've had 9 months of that. There's enough power once you get it going, but the low down torque doesn't inspire the sort of confidence you need to get out of a junction into traffic or onto a roundabout without feeling like a potential hazard
In contrast to that, I've had 2 weeks of lively performance and smooth cruising at low revs. I get juddering, randomly, below about 1300rpm, which I have always had and which is known to be a software 'feature' ( I think it has to do with a rapid transition between m-jet mode and regular mode). That hasn't got any worse since drilling the dpf
I now feel comfortable that I can pull cleanly from about 1400rpm with a gentle squeeze of the gas pedal and there's no bogging down when setting off from a junction.
Perhaps it sounds familiar to others - you set off from a junction and have to apply more throttle than you feel is required and wait for the torque to come in to get you going....and then once you get rolling you have to immediately back off the throttle a bit because you don't want to overshoot and accelerate off too hard once the turbo has kicked in. It was like pedal juggling.