Following on from previous posts in a different thread I tried the stuff Panel uses with no success. However, I opted for the aerosol version (
https://www.irishautoparts.ie/jlm-j02220-2? ) which was probably a bad choice. Looking at the videos mentioned by C5 highlights the problem of the DPF being high in the engine bay hence putting stuff in without the engine running isn't a great option as it'll just find it's way through the bottom of the DPF cylinder straight out the exhaust. Jimmy from Fitzpatricks seems to counter that by pumping the stuff in with the engine running. The aerosol wasn't up to that, the pressure was too low so it just got blown back out the sensor tube. Getting it in without the engine running made no impact on the numbers, either the differential pressure that Jimmy concentrates on or the measured soot value increasing at a far higher rate than the calculated value.
Plan C will be to find a way of pumping stuff in with the engine running so I'm gonna order some cheaper stuff to play with (
https://www.auto-doc.ie/k2/19767838 ) and a bottle/lance that might work with the air compressor in my sister's garage.
Plan D would be a two stage cleaning process. There are some expensive options but there's also a Youtube video testing various cleaning products. In general DPF cleaners are alkaline substances that concentrate on soot which isn't really doing anything the car can't or won't do itself using diesel and extreme heat for automatic regenerations. Clearing the underlying ash requires an acid with substances such as drain cleaners or alloy wheel cleaners proving effective in the tests mentioned above. As soaking is required the DPF should ideally be removed from the car for such a procedure but that's a bit of a cunt with VAGs, requiring removal of the subframe among a lot of other stuff. I reckon it could be done in situ by removing the pre exhaust and blanking off the pipe connection on the DPF and removing the EGR motor or complete cooler unit and similarly blanking that port on the DPF. Then it'd probably just be a case of taking care not to overfill the DPF with whatever fluid is deployed to avoid it getting into the cylinder head through the catalytic converter.
However, it's unlikely that my car will get to Plan D. By my calculations at it's current ash accumulation rate it will be another 50k odd kilos before the Ash level is at it's 80g limit. Assuming no age extensions for 2016 vehicles that'll take it beyond it's taxi life and (depending on EV grant aid availability next year) could well see it into the scrapyard. I'll just tolerate the more frequent than ideal (currently every 80-100k) automatic regenerations unless Plan C helps. Of course the rate could keep increasing which could be an issue requiring attention. In an ideal world, in that case, I'd spend the €500 on a new DPF, swap it out and play about with cleaning the old one... but, if the car is destined for the scrapyard, doing the bold thing would make more sense. Lot's of ifs and buts, I guess.
What I've learned / deduced so far from a testing / monitoring perspective is:
The ash level of the DPF should fill at a rate of 1g per 4,000 kilos.
Automatic regenerations should occur every 200-300 kilos.
Main stealers don't recognise a fault unless there's a DTC. In my case there's no DTCs despite the ash fill rate increasing to a marginal 1g per 3,000 kilos, obviously caused by increased automatic regeneration frequency.
Cleaning the DPF should result in a differential pressure of c.5mBar. Mine hasn't yet gone below c.10 after any of the cleaning methods I've tried. - a bottle of Dipetane into a tank of diesel and the stuff mentioned above sprayed into the DPF with the engine switched off.
Regenerations, be they automatic, passive or forced can cause the engine oil to get diluted with diesel, according to contributors to relevant fora. At first thought one would think that can only happen if a piston ring is faulty but I guess if the diesel injected on the exhaust stroke for regeneration is injected while the piston is at the bottom of the cylinder a (however tiny) amount could transgress the seal in "normal" operation. It's not clear whether the ICU takes the number of regens into account in calculating variable service interval requests so it's probably prudent to use the minimum interval (every 15,000 kilos) for oil changes if the ash is accumulating at a rate higher than 1g per 4,000 kilos.
If/when I get to Plan C or Plan D, I'll report my findings on here!
Oh, I do have a more immediate plan that I forgot to do when I was last at it, so let's call it Plan B Part(ii) - that is to check the differential pressure sensor itself. Differential pressure isn't only an indication of cleaning effectiveness, it's also used by the ECU to calculate the measured soot value. Fortunately it's identical (same part number) to the post exhaust pressure sensor which is located beside it so simple enough to swap them over and see if that has any impact on the live data. I might do that today.
