Mazda 2016 1.6 diesel issues

Barkin

https://forums.moneysavingexpert.com/discussion/comment/81920637#Comment_81920637

Different engines handle DPF issues - regen's etc differently. e.g. not all show an indication that a regen is in progress, so it's easy to switch off before it's completed, then it tries again next time, but the journey's too short to complete, so it tries again next time...etc etc. A recipe for trouble.

Premature DPF problems (we don't know the mileage of the OP's car - only it's current usage) will be due to something other than the DPF itself.

It sounds like the OP bought a car with pre-existing DPF problems, the root cause of which haven't been properly investigated.

FWIW my 2007 Euro 4 diesel has done 180k on the original DPF

paul_c123

https://forums.moneysavingexpert.com/discussion/comment/81920673#Comment_81920673

I concur.

The fear of the DPF failing to regen is something that non-technically-minded people like to pretend they can advise on, but really it isn't that big of a deal so long as some longer journeys are done. And if mainly short journeys occur with occasional longer ones, the DPF has plenty of capacity to store soot then regen once conditions are suitable.

That being said, some cars are just poorer than others in their regen strategy. The Mazda 2.2D is one of the worst, but I've not heard of issues with the Mazda 1.6 (but then they are really quite uncommon cars).

Goudy

DPF's don't actually hold that much soot.

Around 25 to 30g (in old school around an ounce) and your average diesel car will produce around 0.05g to 0.15g per mile but this can increase/decrease at various points in a drive cycle and no two drive cycles are truly the same.

That's between 200 and 600 miles but in reality it's likely to be less, what with cold starts, idling at lights, slowing and speeding up etc. As we know, do this the majority of the time and that's where DPF issues can start.

You also need to factor the filters ability to turn/burn the large particles of soot into smaller particles of ash and store that into the equation of a filters overall life. Generally they will hold between 50g and 100g of ash. Obviously these figures are rough car based figures. A large truck or van for instance might have much larger capacities.

Soot is a byproduct of incomplete combustion, the leaner the burn the less soot but it's hard to ignite such a lean mixture, so on a modern diesel the electronics will work out the best ratio based on things like engine temperature.

This lean burn also produces a lot more heat than a richer burn, heat the DPF can utilise when regenerating. This is one of the main reason you often complete regens on a longer motorway trip. The trip is long enough in time to complete the regen and the conditions within the engine are near perfect, a light throttle/lean burning cruise.

Now there is a misconception that repeated failed DPF regens only effect the exhaust side of the engine as that's where all the faults codes point to. But all that post injected fuel that is meant to burn and turn the soot to ash and the soot still being products is now able to recirculate via the EGR system back into inlet side of the engine. Now the engine has a problem to breath properly and even might have issues with valve operation.

There are also other factors the can influence the DPF system, like air intake leaks and faulty or worn injectors and we know the modern common rail fuel injectors have a service life.

Increasing the ratio of fuel to air leads to far more soot being produced which requires more regenerations and much cooler exhaust temps which are far from ideal when trying to perform a regen in the first place.

Now you could have a mixtures or all of these problems causing DPF issues, but just changing your driving trips/style or cleaning the DPF might not be enough to sort the problem as you are treating the symptoms rather than the cause. This is why DPF issues tend to come back again and again.

Mildly_Miffed

https://forums.moneysavingexpert.com/discussion/comment/81920763#Comment_81920763

And, of course, if a regen is "missed", then the level of soot in the filter is higher, so the next regen needs to be longer to fully complete.