[GUIDE] DPF Experiment and Results

[MrBenjaminHDM]

Intro

Hello,

If like me you love to know how things work then this thread is for you. I've often wondered what makes the DPF tick in my 2015 model V60 with a D5 engine so I decided to research and experiment, then compile my findings here. If you're looking for details for the 1.6 diesel you're out of luck, I believe they are a wet EOLYS DPF and therefore voodoo. However my findings here apply to any current run 2.0 or 2.4 diesel FWD or AWD and I hope they can be of use.

DPF Preface

From VIDA:

For the particle filter to be regenerated, an exhaust temperature of approximately 600 °C is required downstream
of the filter. This is achieved via various engine operations, such as throttling, changed fuel injection, glow plug
activation.

Regeneration can be triggered in a number of ways:
▪ Used fuel volume,
▪ Time that engine has been running.
▪ Distance driven since last regeneration.
▪ Differential pressure across the particle filter or calculated particle weight in the filter.
▪ Start in the workshop using the diagnostic tool.
▪ Particle level in the filter calculated by the engine control module (ECM). What soot
weight each level corresponds to varies between different vehicle variants. Particle levels
are given below translated into soot weights (grams), and what effect they have.

With that in mind there are 5 different levels or circumstances in relation to the DPF based on the calculated weight of soot in the filter. Note that 2.0l and FWD 2.4l have the same Catalytic Converter/DPF combo installed straight off the back of the turbo whereas AWD 2.4 have a separate DPF installed under the floor of the vehicle. Below are the explanation of each level from VIDA.

DPF Soot Levels

Level 1: Engine control module (ECM) starts combustion of soot particles in the particle filter
during highway driving.
Level 2: Engine control module (ECM) starts combustion of soot particles in the particle filter
during normal driving.
Level 3: A text message, Soot filter full, is sent to the Driver information module (DIM), and
the control module sets a DTC.
Level 4: Engine control module (ECM) can no longer start combustion of soot particles of its
own initiative. A further text message, Engine system service required, is sent to the Driver
information module (DIM), and another fault code is sent.
Level 5: More than 100 g soot . Combustion of soot particles cannot be started using the
diagnostic tool.

Engine---Particle Filter----Level 1----Level 2----Level 3----Level 4----Level 5
2.0---------ccDPF--------------NA-----------27g----------32g----------36g----------100g
2.4--------- ccDPF-------------24g-----------27g---------32g----------36g----------100g
2.4----------ufDPF-------------28g-----------30g---------40g----------45g-----------100g

The Experiment

Knowing what we've read above, and considering my 5 mile commute isn't the best for a car equipped with a DPF I sought to find how best to accommodate the DPF, to learn what fills it up, how to regenerate it and to know when it's regenerating. In my case I have a 2.4l with a ccDPF which will trigger regeneration first during motorway driving at 24g or if it does not get the opportunity, on regular roads at 27g.

Simple stuff, Cold engines make more soot, higher revs make more soot and high revs on a cold engine makes a lot of soot. I observed the soot number increase simply when revving the engine on the driveway and although the calculated number may not represent the actual quantity in reality it does affect regeneration which in turn leads to more diesel contaminating the oil, the car would rather regenerate itself and contaminate the oil than get to the point where it has to put a message on your dash.

So for the sake of science I've undertaken some research and tested the regeneration cycles with two methods, I have driven to regenerate and induced a forced regeneration on the driveway with VIDA.

How to tell you're regenerating

First of all the car must be at operating temperature with no outstanding faults, climate settings are all irrelevant as is your driving style. I've found the best way to tell the car is regenerating (If your car has the facility for Start Stop) is to watch the "MY CAR" screen for when ss becomes unavailable, if you open the DriveE menu and select ss it will say "Engine System".

Otherwise you will see increased fuel consumption and possibly a faint burning smell. If you have an OBD reader Cat Temp B1S2 will rise above 400 celcius during regen.

During regeneration the ECU will aim to get the DPF temperature above 600 celcius, I've seen it go as high at 680 celcius. Curiously during a forced regen the car will keep it almost exactly at 575 celcius, 3500rpm (It doesn't half make a racket)

Driving regeneration

So the aim of the game is to keep engine between 30% and 70% load at a fairly consistent speed to allow post combustion injection of diesel, if you leave these parameters or wellie your car to full throttle the ECU will stop post injection to give you the power you're requesting and the DPF will start to cool down, patience is the key here.

Motorway or not I've seen the temps above 600c with smooth driving between the load values above, you can even keep the temps above by maintaining 2000rpm and above whilst stopped if you're brave enough. Myth busted, sticking it into 4th on the motorway does squat all, select the highest gear and keep her steady as she goes.

My test drive triggered regeneration on the motorway the second the car reached operating temperature, Start Stop became unavailable, fuel economy reduced and Cat Temp B1S2 started increasing from below 300c to above 600c. After 27 minutes trying to maintain 60mph with cruise control which kept me under 70% load, 23 miles down the road Start Stop lit back up, fuel economy returned to normal as did Cat Temp B1S2.

I would therefore say that approximately 30 minutes of driving without slowing down/speeding up too often would lead you through a regeneration cycle once started, in traffic exclude the time you are stopping, stopped or getting back up to speed.

Forced VIDA regen

First off let me start by saying I have no idea what ill affects this might have other than royally p***ing off your neighbours. You can initiate a regen using any VIDA Dice that will support your car as well as read out the current vaules, take whatever precautions you must before doing this or you might gas yourself, melt your dog or have neighbourhood watch after you.

The image below is from my attempt, after 32 minutes I bottled it as people were starting to give me funny looks, it reads the soot level before it begins and once more after it completes, you cannot watch it decrease live and the amount of time it takes is not set in stone (VIDA says 30 minutes, obviously it isn't)

The car will, as if by magic, rev to 2500rpm until the desired coolant, oil and fuel temperatures are reached. After that all hell breaks loose and the beast is unleashed, 3500rpm and the mighty 5 cylinder roar for as long as your ears can take it, maybe longer.

As I said earlier it will maintain 575c until it thinks it's burnt every last atom of soot off, my filter was not too full at 25g which calls for a motorway regen, a good way off the 32g that triggers a message on the dash and the 36g that requires such a forced regeneration, and it took 32 minutes to burn off 20g of the soot. The time per soot removal may or may not be linear so factor that in if you're going to do it.



Outro

I sincerely hope this has been of use, I'm using all this knowledge to try and reduce the amount of regens my car does and therefore reduce the amount of fuel contamination in the oil sump, I've been stuffed with the oil overfilled fault and it's all down to interrupted regens.

I hope that none of you get to Stage 4 or even 5 where your DPF takes a swift trip to the bin, if you have any questions I will be glad to try to help and any feedback or missing bits are greatly appreciated. Thanks for reading.