Mazda CX-5 2.2 SkyActiv-D - DPF filling fast

[Serijst]

Hi. Hope this information will be useful for skyactiv-d regeneration understanding :
DIESEL PARTICULATE FILTER REGENERATION CONTROL [SKYACTIV-D 2.2]

Outline

• When the amount of accumulated particulate matter (PM) in the DPF exceeds a certain value, the PCM controls to combust and eliminate PM.
• Two methods are available to combust and eliminate PM, one is automatic DPF regeneration control which is performed by the PCM automatically, and the other is compulsory DPF regeneration control which can be forcibly performed externally. ( so there no any passive regen, only active)

Operation

• The PCM estimates the PM amount accumulated in the DPF.
• Amount of accumulated PM is calculated from the difference in exhaust gas pressures and PM emission amount.
Estimation based on difference in exhaust gas pressures
• The amount of accumulated PM is estimated by comparing the exhaust gas pressures before and after the DPF based on the signals from the exhaust gas pressure sensor.
• The PM emission amount is calculated from the soot generation amount and the PM combustion amount.
Soot generation amount
• The soot generation amount is estimated based on the engine speed, intake air amount, and fuel injection amount.
PM combustion amount
• The PM combustion amount is estimated based on signals from the exhaust gas temperature sensor.

Automatic DPF regeneration control

• The PCM controls to combust and eliminate PM when the vehicle is driven for 10—20 min. with all the following conditions met.
Automatic DPF regeneration control launch conditions
― Engine completely warmed up (engine coolant temperature: 80 °C {176 °F} or more*1)
― Vehicle speed: After 15 km/h {9.3 mph} or more reached (If traffic congestion determined, after reaching 5 km/h {3 mph} or more)
― Accumulated PM amount: Specified value*2—10.0*3 g/L {0.62 lb/ft3}
• After DPF regeneration control launches, it operates until the amount of accumulated PM amount lowers to approx. 0 g/L {0 lb/ft3}.
*1 :If there is little frequency of complete engine warm-up, the lowest engine coolant temperature for launch is 40 °C {104 °F} or more.
*2 :Figure fluctuates depending on the distance traveled /conditions.
*3 :If the accumulated PM amount reaches 10.0 g/L {0.62 lb/ft3} or more, the output control is performed (reduction of PM exhaust amount and exhaust gas temperature), and auto DPF regeneration control is inhibited

[popielasty]

Damn, I didn't look here for a while...

For all ppl wondering if DPF need to be cleaned - PM_ACC_DSD determins it. If PM_ACC_DSD after normal regeneration fall to value close to 0, it's ok. If it stay on higher value, ex. 2-3 it's clogged and it need cleaning.

In SkyActivD SH 12-17yr (without adblue) every cycle starts after 17,71 liters of ON used (PM_GEN reaching linear value ~6 and it's almost equal to ~17l of ON used - I checked it few times) or if DPF is full (PM_ACC_DSD).

[spektr]

Yup, we figured it out yes

[popielasty]

I thought this topic is dead, I checked it in 2019 last time but I was active on many PM that I received, I will repost latest one when I gave some usefull information (but remember - I'm not mechanic and sepcialist, all of those are my experience, lot of forscan logs analysis - mine and other users). I'm gathering experience from polish boards. Basicly, my issue had gone with FCM cleaning of DPF, but in most cases ppl have problems with combustion in their enginge - leaking injector washers (I was surprised, but leaking injector washer can cause lack of cylinder compression, I've met 3 cases when fixing injector washer fixed fast growing of PM_ACC_DSD), malfunctions of turbo (broken clapper arm)/ EGR or clogged intake manifold (carbon). I didn't meet injector malfunctions, they seems to be resistant to damage.

"1. I finally resovled my problem - my DPF was totally clogged. I have done FCM cleaning of DPF and it solved my issue. FCM = high water pressure cealing procedure. My PM_ACC_DSD never go to value close to 0 after normal regenerations... After cleaning by FCM method, my PM_ACC_DSD goes to 0 every regeneration.
2. EGR - before I have done cleaning of DPF, blinding my EGR gave me 2x range between regenerations. Firstly, I had about 50-60km, after blinding EGR i had > 100km (100-120km).
3. Basicly problem with DPF can be caused by two reasons: 1. clogged DPF (like mine, I had broken turbocharger, leaks of oil, it cause DPF clogged. 2. high soot from enginge. It's much harder to find a solution here... High soot from enginge can be caused by faulty turbocharger, fultry injector, injector seals (very important in this enginge, I suggest replace them every 60-80k km - I almost broke my enginge, my oil strainer on oil pump was tottaly clogged by carbon that was exist becouse injector sealing was broken).
4. I will look for pic of my EGR block plate, I have it somewhere. Basicly, when you blind your EGR you will cause check enginge light on dash. Then you can do 2 things: 1. make software mod to get rid of check enginge 2. make a little hole in plate, like 8mm in my case and check doesn't appear anymore.

Hope this will help you somehow. First, check PM_ACC_DSD after normal regeneration process. It will tell you where if the problem is number 1 or 2. "

I was gathering my DPF stats here: https://docs.google.com/spreadsheets/d/ ... edit#gid=0 (long time ago). Now I hit 250000km on my CX-5, regenerations are in range of 150-300km, depends on my ON usage - now I'm doing short trips, having consumption above 10/l per 100km, so cycles are closer to 150km. When I was on my vacation and I wasn't in hurry, I was reaching 260-300km regen cycles.

[Mareng]

I have the 2014 saloon, same engine and in 2019 about November I got the DPF Needs Inspection light come up, luckilly I was close to home.
I checked with Forscan, sensor P243c - DPF Frequency Bank 2.

At the time it didn't mean a lot to me. Took it in to the dealer who I have got a good working/technical relationship with. He said its the DP Differential Pressure sensor which sits just underneath the rear heatshield, a plug on the side and two rubber hose connections out the bottom and held to a bracket with two machine bolts. After parting with £200 a new part (No. SH01-182B2) was fitted and was fine. It seemed they had trouble with some of these parts ( more poor QA) on earlier models.

February 2020, so just 3-4 months later after a 45 minute run at 70 mph in 4th gear whilst returning from a social occasion this light came on again.
Took it in the following day, explained the part was new only a few months ago. They had it for a week and checking when they had a chance, carried out a Forced Regen and cleared the fault code.

They said often the pipes clog up with soot, but these were clear.

It was ok until February 2021 ( I had only done 3500miles since then, due to Covid restrictions, with a few 400 miles long runs , 30 mile blowouts and the rest local stuff). I had just finished a 30 mile blow out when the light came up. And yes, same code. So I removed the sensor and blew down each pipe without restriction, so is it a dodgy sensor or what? It Is due in this week for them to look at again. If I knew a bit more I would fix it myself, but could I clear the code. Checking the pressure readings coming off the sensor they are changing with respect to rpm (off load) as one would expect. When the light came on it had just finished an active regen 0.7 mile ago. So it seems the sensor is working. One thing they did say last time , is if there are too many Regens then it will throw this one up. The readings PM ACC 0.51g/l
PM ACC DSD 0.51, PM GEN 0.05g/l. EXH Press1 83kpA. After the regen.

I, like many of you experience a 30-50 mile regen frequency. This I calculate from number of regens since last filling the fuel tank and the mileage between fillings. The other measurement is total miles on the clock divided by number of regens from new which obviously started high but since 2016 I think when we had the ( sneaky beaky ) big software update following VWGate, the frequency of regens and fuel consumption has increased. Shortly after the software update which turned out to be increasing the opening of the EGR there was a free inlet manifold decoke, due to the latter. Some owners experience 90% blockage, with all the dash lighting up with codes.
One of these days, when I am feeling brave I will remove the DPF and soak it in rich soapy water as this dissolves carbon. I used to use soapy water for decarbing my EGR valve on another make. As it was a vacuum operated one I would just drop it in the soapy water along with the EGR cooler and they used to come out shiny after the first time. It used to be a yearly thing when doing a service. The Mazda, is electrically operated and its a bit busy round there.

I will let you know what the out come is.

[spektr]

@popielasty...Very nice satistics5

[spektr]

@Mareng.."The readings PM ACC 0.51g/l
PM ACC DSD 0.51, PM GEN 0.05g/l. EXH Press1 83kpA. After the regen."

So this values are after sucessful dpf regeneration right? The values are not as good as it should be. Look at the popielasty data in excel (2 posts up)...usually pm acc dsd after regen should be around 0.1g/l, it depends on how hard you are driving at that time. But usually the number is around 0.1.

So, injector washers could be the cause, EGR blockage, or DPF itself.

[Mareng]

The outcome of the above was a failed DPF differential pressure sensor ( or Exhaust sensor Bank 2 as it is designated by Mazda).
As the sensor had been replaced at my expense by the dealer less than two years ago it was replaced free of charge.
Whilst the car was in they carried out a Forced Regen and also a Fuel Injector relearn and made sure the two pipes up to the sensor were clear.

The testing of the pipes can be done by the owner by removing the sensor from the rubber pipes, starting the engine and have an assistant slowly increase the rpm. You will get a good jet of gas from the 'before DPF' with a weaker one from the other 'after the DPF'.
The SM said the readings were fine.
There is another Exhaust pressure sensor ( Bank 1) which is just a straight pressure sensor and located more central along the camcover.

Just need permission to travel with regards Covid travel restrictions and give the car a good run out.
Blanking the EGR is not an option, in fact illegal as it causes an excess of NOx, those countries like the USA and Eastern Europe may not have such high standards as Great Britain hence all the inefficient, overengined and polluting cars and trucks in the USA.

[spektr]

Thank you for your info!

[smartguy69]

I had so many dpf issues on my 2007 Mazda 2 litre with the GG engine that I vowed never to buy another diesel again. I did, a Ford Kuga diesel which never goes out of the city with short journey of about 20 minutes and couldn't even tell you when my car is doing a regeneration and had zero problems in two years.

The Ford system works extremely well.

How are Mazda these days with failed dpf regenerations.