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2024-07

On this page I will share a detailed analysis of some of the more interesting (/longer) trips I recorded in July 2024.

Trip #1 - Suspicions confirmed​

- Date: 19 July 2024
- Start: 15:45
- End: 18:59
- Duration: 3h 14m
- Distance: 110 miles (177 km)

View on Chart (trip is highlighted on the chart with a purple background)

This was the very first trip I recorded and it immediately gave me valuable insights. I believe it serves as a prime example of how the DPF is not able to regenerate itself during normal driving conditions in the UK.

SootScout Trip Analysis - 2024-07 #1

  1. When I began my first recorded trip on the 19th of July, the DPF Soot Mass was at around 14g. (Remember, that I was driving with a brand new DPF that was fitted just a few days before this trip). Knowing that I was about to drive over 100 miles, mostly on the motorway, I was expecting the DPF to do a passive regeneration at some point during the trip. Between 16:05 and 16:40 I managed to keep the speed above 50 mph, which, according to official guidelines, should have been enough for the car to perform a passive regeneration. If you look at the Particulate Filter DPF Regeneration chart (2nd from the top), you can see that the car was indeed trying to do a passive regeneration during this period (lots of orange bars). Yet, as you can see from the Exhaust Gas Temperature Bank 1, Sensor 3 (°C) chart, the exhaust gas temperature was not high enough for the soot to burn off (the temperature kept staying under 500°C). And, therefore the soot kept on accumulating. Not a good start...

  2. From around 16:43 to 17:30 I was stuck in traffic on the motorway, so in this period the DPF did not have a chance to perform a passive regeneration.

  3. After 17:30 I got out of traffic, and for about 15 minutes, the car continued its attempts to do a passive regeneration. If you look at the exhaust gas temperature and DPF soot mass charts, you can see that the temperature was finally high enough (above 500ºC) for (a very little) soot to burn off. From 17:46 to 17:56 I was back in traffic. From 17:57 traffic finally cleared up, and was driving constantly at 50 mph for the next 25 minutes. In this period the exhaust gas temperature did not get anywhere near the required temperature for passive regeneration to take place, and therefore the DPF soot mass kept on increasing. From 18:22 to 18:30 I was back in traffic again, and the DPF stopped its attempts to do a passive regeneration.

  4. Once the traffic cleared up at 18:30, I was able to drive at 70 mph. The car resumed its attempts to do a passive regeneration, but the exhaust gas temperature was still not high enough for the soot to burn off (staying below 500°C). At this point, the soot was at around 28g. But then, out of the blue, the car decided to perform an active regeneration! (See the red bars on the Particulate Filter DPF Regeneration chart). This brought the exhaust gas temperature up to the required level (550-600ºC), and the soot started to burn off. At 18:51 I arrived at my destination, looked at my phone, and noticed that the DPF was still busy doing the active regeneration. I continued sitting in the car with the engine running to allow the DPF to finish the regeneration process. At 18:58 the active regeneration stopped and transitioned into a passive regeneration. This went on for another minute or two, and then finally, the regeneration process was complete. The soot was back at 10g. At 18:59 I turned off the engine and the recording stopped. (Next recording starts at 19:47)

This first trip highlighted a few important things already:

  • No matter how much I seem to be driving on the motorway at required speeds, the DPF is not able to regenerate itself during normal driving conditions on UK motorways.
  • Passive DPF regeneration appears to pause the moment I take my foot off the gas pedal. Hence, the continuous flap between passive regenerating and not regenerating. Even though the car is travelling at 70 mph, if my foot is off the gas pedal, regeneration stops.
  • Climbing hills seems to help the DPF to reach the required temperature for passive regeneration. Try adding the Altitude chart to the page, and you will find that the momentary drop in soot mass was thanks to the car climbing a hill. This is something I noticed in subsequent trips as well and will document in more detail later. (Note that for whatever reason the Altitude recordings are quite sporadic, hence the big gaps in the chart).
  • When I am about to turn off the engine the car might be halfway through an active regeneration. Always look at the phone before turning off the engine to make sure the regeneration process is complete.

Trip #2 - To regenerate or not to regenerate?​

- Date: 19 July 2024
- Start: 21:22
- End: 22:30
- Duration: 1h 8m
- Distance: 70 miles (112 km)

View on Chart (trip is highlighted on the chart with a purple background)

SootScout Trip Analysis - 2024-07 #2

  1. For whatever reason, for the first 8 minutes of the trip (21:22-21:30), the top 3 charts do not have any data. This seems to be a bug in the Car Scanner App, as from some sensors it does record data (e.g. vehicle speed).

  2. For the remaining part of the journey (21:30-22:30) the speed was constantly above 50 mph, and the car was trying to do a passive regeneration non-stop. Did it succeed? Not a single bit. The exhaust gas temperature was not high enough for the soot to burn off, and the DPF soot mass kept on increasing. At the beginning of the trip it was at 11g, and by the end it was at 23g. That is 1g increase every 5 minutes while driving on the motorway.

Trip #3 - Active regeneration to the rescue! (Again...)​

- Date: 20 July 2024
- Start: 11:18
- End: 12:45
- Duration: 1h 27m
- Distance: 82 miles (132 km)

View on Chart (trip is highlighted on the chart with a purple background)

SootScout Trip Analysis - 2024-07 #3

  1. For about 13 minutes (between 11:27 and 11:40) the car was travelling at speeds well above 50 mph (topping at 77 mph), and the DPF was desperately trying to perform a passive regeneration. Needless to say, it was not successful. The exhaust gas temperature was not high enough for the soot to burn off, and the DPF soot mass kept on increasing.

  2. Then, out of a sudden, at 11:40, when the soot mass reached 28g, the car decided to perform an active regeneration. This brought the exhaust gas temperature up to the required level (600-650ºC), and the soot started to burn off. It was doing an active regeneration from 11:40 to 11:54 (14 minutes), and then transitioned into a passive regeneration and then to no regeneration at all. This has brought the soot mass back to 4g.

  3. For the remainder of the trip, the car continued to travel at speeds above 50 mph (albeit with a few stops in traffic), and the DPF was trying to do a passive regeneration. Again, it did not succeed a bit as the exhaust gas temperature was not high enough for the soot to burn off. The soot mass kept on increasing, and by the end of the trip it was at 10g.

Trip #4 - A British car made for the German Autobahn?​

- Date: 20 July 2024
- Start: 13:44
- End: 17:51
- Duration: 4h 7m
- Distance: 261 miles (420 km)

View on Chart (trip is highlighted on the chart with a purple background)

SootScout Trip Analysis - 2024-07 #4

Things started to get interesting with this trip...

  1. In the first 40 minutes of the trip (13:44 - 14:24) it was pretty much business as usual. The car was travelling at just below 80 mph, and the DPF was trying to do a passive regeneration. Given the increased speed, the exhaust gas temperature entering the DPF was slightly higher than usual, but this was still not enough for the soot to burn off. Then, something unexpected happened. At 14:24 I had to slow down to a complete stop, (for 2-3 minutes) for a reason I no longer remember. Then, while stationary, out of a sudden, the soot mass dropped from 18g to 10g! There was no active regeneration happening, and the exhaust gas temperature was not high enough for the soot to burn off. So, what happened here? I have no idea...

  2. In the next section of the trip, we were back to the usual business. The car was travelling at speeds above 50 mph, the DPF was trying to do a passive regeneration, yet the soot mass kept on increasing. This went on until 15:13, at which point the exhaust gas temperature started to reach temperatures above 500°C, albeit just for a few seconds at a time. But, even if just for a few seconds, this has allowed the DPF to burn off some of the accumulated soot. For the first time during this trip, finally the DPF was able to do a (mini) passive regeneration! But how did this happen?

    I have identified a few key ingredients:

    • Driving at speeds above 80 mph
    • Sudden drop in speed, and then quickly accelerating back to above 80 mph

    Every time an acceleration like this happened, the exhaust gas temperature would spike above 500°C, and the soot mass would drop slightly (see the white arrows pointing out these accelerations on the chart).

  3. Now would you look at this! At 15:46 the soot mass went under 20g (thanks to the effective passive regeneration) and the DPF was able to keep the soot under 20g for nearly 80 minutes! In this period the exhaust gas temperature continuously spiked above 500°C, and the DPF was able to burn off the soot. Finally, the DPF was working as designed! But again, what was the key to this success? The exact same as before:

    • Driving at speeds above 80 mph
    • Sudden drop in speed, and then quickly accelerating back to above 80 mph

    I have pointed out with white arrows on the chart every time the speed quickly increased, and the exhaust gas temperature spiked above 500°C.

  4. Once the soot mass reached 20g again, the DPF was not able to keep it under 20g anymore. Why? My speed went back to below 80 mph, and this was no longer enough for the exhaust gas temperature to reach above 500°C. Towards the end of the trip, I was able to drive at speeds above 80 mph again, and passive regeneration was successful again. If you look at the charts, you can see that yet again, every time the speed quickly increased, the exhaust gas temperature spiked above 500°C, and the soot mass dropped.

When the trip started, the soot mass at 10g, it then went up to 25g, and when the trip ended it was at 20g. The soot mass dropped several times, and not a single time an active regeneration was performed!

It is all nice and everything, but I hope you see the problem here. It is great that we finally identified the conditions under which the DPF is able to passively regenerate itself, but the speed limit in the UK is 70 mph!

Therefore... my conclusion is that my car surely was not designed to be driven in the UK!

2024 July Trip Summary​

  • Total distance travelled: 1835 miles (2957 km)
  • Number of active regenerations: 12
  • Average distance between active regenerations: 119 miles (192 km)
  • Average time to regenerate: 18 minutes
  • Average soot mass before regeneration: 29g

Active Regeneration Details​

  1. 19 July 2024, 18:35 - 18:57 (22 minutes, 28g -> 11g, start at mile 105, end at mile 110. Had to wait several minutes at the end of the trip stationery for the regeneration to complete)
  2. 20 July 2024, 11:40 - 11:55 (15 minutes, 28g -> 4g, start at mile 197, end at mile 216)
  3. 21 July 2024, 13:10 - 13:27 (17 minutes, 28g -> 7g, start at mile 705, end at mile 719)
  4. 21 July 2024, 16:59 - 17:15 (16 minutes, 28g -> 6g, start at mile 910, end at mile 931)
  5. 24 July 2024, 19:25 - 19:43 (18 minutes, 29g -> 4g, start at mile 1107, end at mile 1126)
  6. 26 July 2024, 20:53 - 21:11 (18 minutes, 28g -> 5g, start at mile 1296, end at mile 1317)
  7. 27 July 2024, 21:06 - 21:08 (2 minutes, 31g -> 31g, start at mile 1446, end at mile 1446. This one is weird... The active regeneration just started as I was about to park the car, and then stopped after 2 minutes. As you can see the on the chart, the regeneration status went back to 0 [off] before I turned off the engine, i.e. it was not me who stopped the regeneration).
  8. 28 July 2024, 11:09 - 11:34 (25 minutes, 32g -> 4g, start at mile 1447, end at mile 1472)
  9. 28 July 2024, 21:48 - 22:11 (23 minutes, 33g -> 7g, start at mile 1611, end at mile 1620)
  10. 30 July 2024, 08:07 - 08:24 (17 minutes, 27g -> 10g, start at mile 1725, end at mile 1733)
  11. 31 July 2024, 08:09 - 08:17 (8 minutes, 29g -> 26g, start at mile 1785, end at mile 1786. This one was also cut short. It seems like the DPF stops active regeneration if shortly after starting regeneration the vehicle is not moving for a certain period of time).
  12. 31 July 2024, 16:29 - 16:41 (12 minutes, 31g -> 17g, start at mile 1810, end at mile 1816)