Last Monday I changed the dpf test-reset algorithm to change it from being the quick and dirty time based system to using the 'more correct' method which is to read the dpf clogging% value reported by the ECU. I can trigger the dpf test-reset to occur at any clogging % value now.
For programming convenience it currently resets when the reported value is at or above 0x0C00, which represents about 46% clogging. I ran for over a week restting it at about 2.2% clogging, confirming there doesn't appear to be any detrimental affects from resetting the test-reset counter too often. It's difficult to see why there would be a problem, but it is worth testing things like that to make sure.
I'm just a few hundred miles short of 5000 miles since I first drilled into the dpf, with no regrets and only benefits to talk about. I can't remember the last time I needed to apply a lot of revs to get off the line at a roundabout and driving in traffic is as easy as with any other car I've driven, thanks to the turbo spooling up as quickly as it was always intended to do. In turn the clutch is getting a far easier time of it too - because the engine pulls hard from low revs the clutch is usually fully engaged by 1400rpm so there's very little riding of the clutch required any more.
The EGR defeat software I'm also running has had a little hiccup though, the algorithm I use to continuously monitor for fault codes in the pending and confirmed fault lists is too forgiving, because this morning I got a check engine light when there were no other faults present, apart from the P0401 caused by the blanking plate in the EGR circuit. I just need to tighten up the testing over successive drive cycles, but for now I'm glad that it's too sensitive because it means that any other fault code which appears will not be ignored and carelessly deleted (with possible negative effects)
I had my best mpg today on my regular Sunday run, Cumbernauld to Livingston over the same route I always use. Previous best was 49.2mpg (Before drilling the dpf best was always below 44mpg) but somehow today it was 52.7mpg, without needing to try too hard.
In theory these figures should represent the worst mpg I can achieve thanks to having the largest diameter tyres
of almost anybody else. 235/50 r18's(692mm) have a greater diameter than 235/40 r19's (671mm) but this does mean I turn fewer revs per mile than a standard 1.9. At 70mph I have a little over 2000rpm. The speedo is accurate with these tyres so I'm guessing that the odometer also shares the same accuracy, considering that it runs from the same speed sensing devices. The last brim to brim was very close to indicated economy, I had an indicated 37mpg on Trip A and 37.2 mpg via brim to brim calculation. (Low figures, for obvious reasons
These big tyres are uneconomical winter tyres which I'll probably be taking off in spring. Standard tyres on 18" rims are 669mm, standard on 19" are 671mm. I'll probably either go standard 18" or 225/50 r18's (Popular Audi size) which , although 10mm larger than standard at 682mm the narrower width should give better economy. I think I must have got used to the gentler ride of 50% profile's now, the suspension hasn't been as jumpy since fitting the current set . I also like the way the tyres fill the arches more too