Problems with DPS system in Mazda CX5 (or other)

[LGMV]

considering to buy CX5 and some posters kindly pointed out issue that may possibly occur with 2.2Diesel Version of CX5

when used on short runs due to the "regen" not being able to do its job properly on short trips.  As understand it, to achieve

the high temperatures needed for regen, the engine must be running at high revs for a length of time.   With traffic being bad

even longer city trips might make this situation (longer high revving trips) a problem.   Ultimately, this would lead to clogged

filter and engine degeneration.  Of course, the vehicle would be covered under warranty, but personally do not like the idea of 

buggering the engine or spending loads of time in discussions with the dealer.  Am envisaging a situation where the car is brought

to a standstill in a supermarket carpark and the regen has kicked in and then having to basically drive out of the carpark and taketh car on a

long trip until regen has finished, OR, risk clogging the filter by turning the engine off.

Not sure if this applies to all recent diesels (i.e those fitted with mandatory DPFs) and would appreciate feedback from any more 

experienced readers/owners on whether this would be a problem,

A poster did mention they've seen plenty of CX5s running round BKK for example,  but as understand it, the lDiesel 2.2 CX5 from Mazda has

only been selling for 5 months so is this too short for techs to have started getting feedback on problems?

Also, the dealer seems to suggest this latest model has not received any complaints, but of course they would say that, and may be

it's too early?  Apologies in advance if have got the situation incorrect regarding the potential problems but would appreciate

feedback from any users/ readers, many of whom will have good experience of short runs for diesels with DPFs

 

[Sam Lin]

The diesel has been selling since late 2012 here, in both the CX5 and the Ford Ranger. The new generation is a small evolution of that same engine. The sample size of cars having no regen issues, specific to Bangkok, is huge. The dealer is correct that the new gen is only 5mo old and any new model-specific issues will not have much visibility or knowledge base yet.

 

Turning the engine off before the end of DPF regen will not clog the filter. It will simply require another regen cycle next the time the car is run up to temp. If you intentionally shut it off every time it tries to regen, it could cause an issue, but that's not a realistic usage case. Even if you have 3 2min short drives, you'll have a longer drive 10min or more in between where regen will complete its cycle, especially given Bangkok traffic.

[LGMV]

Thanks for that information.

6 hours ago, Sam Lin said:

Even if you have 3 2min short drives, you'll have a longer drive 10min or more in between where regen will complete its cycle, especially given Bangkok traffic.

1. Ok, so even if that 10 minutes drive is at low revs (stop start slow traffic), the regen will work?.  I mistakenly understood that the motor had to be running at high revs for 15 - 20 minutes for regen to work.

 

2,  I wonder if Thailand's heat is actually a plus point for the regeneration, in that it will work at lower revs?   Heard that only short trips in cold countries is the worst case scenario for it not being able to kick in.

 

 

 

[Jitar]

The Ranger and other trucks in Thailand do not have DPF's fitted so they are not relevant.  

The early CX-5 DPF systems were not set up well and some cars had problems with oil dilution.    Mazda revised their software to improve this in 2013. 

 

Some other manufacturers have also had problems with DPF's.  The systems vary between models but many DPF's require hot exhaust temperature and minimum road speed to regen.   The regen cycle is not obvious with some and not related to engine rpm only.  Hi revs and warm climate may not help.  DPF's do not like exclusively short drives and frequent cold starts.  

 

I don't know the CX-5 in detail but other DPF equipped cars I drive need 5 min to warm up and ~10min sustained driving above 60 km/h for the regen cycle to work.  High load and longer drives are better.  

 

If a car is predominantly in heavy city traffic, better to use the petrol engine version.  Pity the 2.5L petrol CX-5 is no longer available. 

 

[LGMV]

Thanks, yes, I was going to ask what was the connection between Ford Ranger and CX5 Engines.   Presumably all late model diesels, Pajero, Everest will have DPFs and so those would be susceptible to the same issues on exclusively short runs.    According to one auto expert (copied below) 4 x 15 minute drives at above 60 would be sufficient so, that is basically one longer trip a. week, which would not be a problem.

 

So what you saying is that it is possible that a driver would not even know the regen cycle was running.  Understood that the regen requires a infusion of fuel and that that on the CX5 you will notice the MPG meter suddenly show you are doing a terrible mpg (or something like that).  

 

Yes it is a pity the 2.5 petrol is not available in Thailand, seems to be available just about everywhere else.

 

 

Particle filters are storage facilities for soot. In some driving conditions (usually 60-80km/h plus, for periods of 5-15 minutes, plus, continuously) they turn into little furnaces and burn off the soot. This is a good thing. It's what they are designed to do.

Unfortunately, if you don’t do the driving described above for a minimum of about an hour each month, the burn-off does not happen, and this starts clogging the filter. If the warning light comes up on the dash, you either go for a drive highway drive promptly or go to a mechanic/dealership where they can manually regenerate the filter. If you don’t do that, the filter blocks, the car goes into ‘limp’ mode, and the filter may need to be replaced - for $4-7k, depending.

Mazda did have a problem with oil dilution in early CX-5 diesels - they fixed this with minor hardware and software changes to the early units as they came in for service. Oil dilution is a normal part of diesel engine operation, and it needs to be balanced against the diesel particle filter regeneration protocols. Basically they got the balance wrong in early units.

 

[Jitar]

AFAIK, like the trucks they are based on, the Pajero Sport and Everest do not have DPF's in Thailand.  In countries like Australia, these models and their truck relatives do have DPF's.  

 

[LGMV]

Thanks, that is useful info!