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Faster DPF regeneration

125K views 255 replies 45 participants last post by  Sternchallis 
#1 ·
If you notice that regen has started (high consumption, exhaust noise, i-Stop engine indicator), just downshift a gear or two. When engine revs over 3000, regen is done in less than 5 minutes.
 
#146 · (Edited)
All these posts about DPF filling fast. It is not the fault of the DPF, which is doing its job.
Excess carbon which blocks the DPF frequently is caused by bad combustion in the cylinders.
The likely culprit are the injectors as I believe there was either a bad batch of nozzles fitted to 2013-on, not sure on range of years, but I have heard up to 2016.
It is well known to Mazda local head offices, but not the dealers. They will try and replace sensors making money each time it doen't work.
The following graphs might explain the change.

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After an injector change readings chaned dramatically.
DPF still fills up requiring a regen but at circa 200 miles, not 28. Engine readings all taken via Forscan .
 

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#147 ·
All these posts about DPF filling fast. It is not the fault of the DPF, which is doing its job.
Excess carbon which blocks the DPF frequently is caused by bad combustion in the cylinders.
The likely culprit are the injectors as I believe there was either a bad batch of nozzles fitted to 2013-on, not sure on range of years, but I have heard up to 2016.
It is well known to Mazda local head offices, but not the dealers. They will try and replace sensors making money ach time it doen't work.
The following graphs might explain the change.

View attachment 286480 View attachment 286481 View attachment 286484
After an injector change readings chaned dramatically.
DPF still fills up requiring a regen but at circa 200 miles, not 28. Engine readings all taken via Forscan .
How did you get the injectors checked and who/where did you get them changed. I'm on a 66 plate and have seen a slow reduction in my regen intervals where it'll be between 90 - 125 miles currently depending on my driving
 
#148 ·
JPK, whats you total mileage?

I used my local Mazda dealership as a sensor kept coming up( see image with the code). They replaced it once on my dime, then it went again so they thought, so they replaced it on their dime, then it went again.
I would think the original sensor is probably ok. Don't let the dealership talk you into a new one, with fitting and diagnostics it will cost you £200 and thats not the problem, unless they can show you testing it and prove it ( which they probably cannot). The code will come up again, which is overfrequent regens.

So the SM said that cannot be right there must be another problem, he calls Mazdaeur Kent and they asked for a scan of my ECM, then a deeper scan pulling off allsorts of stuff that we haven't access to with Forscan. Then they wanted the injectors removing and and the nozzle tips iwo the holes photographing to proove the holes were elongating. From the photos I took with a DSLR on a tripod with remote release and focused to the limit of the 18/55mm lens , you still could not tell, though they did look a bit rough.
Eventually it was decided to replace them as they were not getting any better. Mazda Eur know about this but your average dealer hasn't a clue because they have no experience of fuel injectors nor the technology behind them. They just fit parts. They don't test injectors, no equipment ( which is speacialised and expensive) and neither have they the training to know what they are looking at or the time.
During my apprenticeship I learnt how to dismantle, overhaul the pintle and guide, reassemble and calibrate, also what to look for and test in a bad one. These were the old CAV type pressure operated injectors, not common rail solenoid operated types as fitted to most modern diesels now.
Where are you located? Any where near Newbury?
The other alternative is look for a fuel injection specialist that only deals with injectors and pumps and has the test equipment and know how.
If you are in this area
Head Office:
Feathers Diesel Services

Unit G12, Lock View,
Lowfields Business Park,
Elland, West Yorkshire, HX5 9HD

They will know what they are doing, in fact Mazda used to use them , which just shows how much Mazda knows if they have to go outside to the experts.
Mazda does not show on their parts list a separate pintle a guide, only a complete injector. The injectors are made by Denso in Japan which is part owned by Toyota ( used to be wholly owned by them) and they make injectors for most Japanes cars, plus Vauxhaul and Ford.
Do you have an OBD reader and Forscan software?
A reader is about £20 and the Forscan Lite is about £4-5, down loaded to to a mobile device, be it a phone, tablet or even an old phone without a sim card which works as a tablet.

With that you cn see how many regens you have done over a certain number of miles. I check mine each time I fill up and take my fuel figures. Total mileage divided by regens from new is one way , but previous regen total from present divided into the miles covered will give you the mileage frequency. Ideal frequency is 150 - 200 miles, depending on type of driving. It looks like you are going through what I did.
Without Forscan you are really guessing.
It seems the problem only become apparent in the 40k mileage area and starts to drop off reall quick then as you approach 50, much like us really.
I paid £2.2 k for Mazda to do it, the expense is in the parts not the labour which is only about an hour to 90 minutes.
As I am planning on keeping the car it was worth me spending that money on it. Don't be persuded to take out the insurance, I looked at it and it was worded a bit vague as to whether you was covered. Selling it on is not very ethical giving somebody else the problem.
The thing is the problem is disguised, the car runs well, sounds good but fuel consumption suffers eventually as you can see from my graphs.

Keep in touch, there are a few cars coming up with the problem, three came up within a couple of months of mine happening, so my SM knew what he was looking at and what to do.

Both the SM and myself learnt a lot about this.

If you go to a Fuel Injection specialist they need to clean out your injector pockets, fit the latest new sealing washers that are tin coated then tighten them down to the latest specification that came out in 2017 I think.
 

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#149 ·
JPK, whats you total mileage?

I used my local Mazda dealership as a sensor kept coming up( see image with the code). They replaced it once on my dime, then it went again so they thought, so they replaced it on their dime, then it went again.
I would think the original sensor is probably ok. Don't let the dealership talk you into a new one, with fitting and diagnostics it will cost you £200 and thats not the problem, unless they can show you testing it and prove it ( which they probably cannot). The code will come up again, which is overfrequent regens.

So the SM said that cannot be right there must be another problem, he calls Mazdaeur Kent and they asked for a scan of my ECM, then a deeper scan pulling off allsorts of stuff that we haven't access to with Forscan. Then they wanted the injectors removing and and the nozzle tips iwo the holes photographing to proove the holes were elongating. From the photos I took with a DSLR on a tripod with remote release and focused to the limit of the 18/55mm lens , you still could not tell, though they did look a bit rough.
Eventually it was decided to replace them as they were not getting any better. Mazda Eur know about this but your average dealer hasn't a clue because they have no experience of fuel injectors nor the technology behind them. They just fit parts. They don't test injectors, no equipment ( which is speacialised and expensive) and neither have they the training to know what they are looking at or the time.
During my apprenticeship I learnt how to dismantle, overhaul the pintle and guide, reassemble and calibrate, also what to look for and test in a bad one. These were the old CAV type pressure operated injectors, not common rail solenoid operated types as fitted to most modern diesels now.
Where are you located? Any where near Newbury?
The other alternative is look for a fuel injection specialist that only deals with injectors and pumps and has the test equipment and know how.
If you are in this area
Head Office:
Feathers Diesel Services

Unit G12, Lock View,
Lowfields Business Park,
Elland, West Yorkshire, HX5 9HD

They will know what they are doing, in fact Mazda used to use them , which just shows how much Mazda knows if they have to go outside to the experts.
Mazda does not show on their parts list a separate pintle a guide, only a complete injector. The injectors are made by Denso in Japan which is part owned by Toyota ( used to be wholly owned by them) and they make injectors for most Japanes cars, plus Vauxhaul and Ford.
Do you have an OBD reader and Forscan software?
A reader is about £20 and the Forscan Lite is about £4-5, down loaded to to a mobile device, be it a phone, tablet or even an old phone without a sim card which works as a tablet.

With that you cn see how many regens you have done over a certain number of miles. I check mine each time I fill up and take my fuel figures. Total mileage divided by regens from new is one way , but previous regen total from present divided into the miles covered will give you the mileage frequency. Ideal frequency is 150 - 200 miles, depending on type of driving. It looks like you are going through what I did.
Without Forscan you are really guessing.
It seems the problem only become apparent in the 40k mileage area and starts to drop off reall quick then as you approach 50, much like us really.
I paid £2.2 k for Mazda to do it, the expense is in the parts not the labour which is only about an hour to 90 minutes.
As I am planning on keeping the car it was worth me spending that money on it. Don't be persuded to take out the insurance, I looked at it and it was worded a bit vague as to whether you was covered. Selling it on is not very ethical giving somebody else the problem.
The thing is the problem is disguised, the car runs well, sounds good but fuel consumption suffers eventually as you can see from my graphs.

Keep in touch, there are a few cars coming up with the problem, three came up within a couple of months of mine happening, so my SM knew what he was looking at and what to do.

Both the SM and myself learnt a lot about this.

If you go to a Fuel Injection specialist they need to clean out your injector pockets, fit the latest new sealing washers that are tin coated then tighten them down to the latest specification that came out in 2017 I think.
I'm in Manchester and I'm at 91000 miles now, I do around 16000-20000a year mostly motorway driving which is meant to be what these engines are built for which is why I've been surprised by the regen frequency. I've got the full license version of forscan, and I always monitor my regens making sure I never turn off the engine mid regen. Mazda changed an O2 sensor and cleaned it under warranty a couple of years ago as they found evidence of excessive carbon buildups. I've thrown a lot of money at mine doing the suspension, aero kit etc so I wanna run this car past 200000 miles like my old Corolla if possible so if it fixes the problem, I don't mind spending the money
 
#151 ·
Thanks JPK.

If I can help anybody on this problem as I learnt the hard way and it was a bit of a learning curve for my SM then I will.
With those sort of miles and driving type it certainly won't be a clogged DPF from soot, it could be ash, but I think you said you had the DPF cleaned by ultrasonics so hopefully that should have taken care of any ash stuck to the honeycombe.

Now I don't think there is a PID that you can interpret to say your injectors are failing. There is the fuel learn graphs, but its knowing what to look for and I don't think dealers and their mechanics are that smart. In Mazdas world this isn't supposed to happen nd it was found out by accident that a lot of cars injectors were failing.
You have two choices, wait until the sensor alarm P243C:00 :2F or on the dash DPF INSPECTION REQUIRED steady warning , not flashing. That leads the mechanic to the dp sensor shown above. If your interval is getting to around 30-40 miles the ECM is saying there are too many Regens in a certain number of miles and flags that code up. At that point I would have the injectors changed (so start saving). Even with that code up the car runs fine. I was running up to Hull from Newbury every month sat on 70 mph for 220 miles and it ran without a hitch, just regening every 30 miles or so. Though ifleave it too long the holes in the nozzle will start to join up then the end falls off complete with anything that will go through the hole and thats when you end up with bent valve stems, rattling turbo etc.
If your flush, you can change them now if itsproven they are at fault.
You can go down the dealer route pushing for a partial warranty claim, thats down to the SM and how good a working relationship you have with him and if he will take your side. If you go that route everything is under warranty for 2 years.
Or you can go over to Feathers and see what they can do for you. They may put in new ones or refurbished injectors with new nozzles and internals.
There are these also:
Autobase Manchester which are Bosch agents which deal with fuel injection systems and injectors.

Good reveiws from this one:

Plus Feathers.

I would be very wary of buying anything off E-bay particularly as you are planning on keeping it 200,000 miles.

Your about double my mileage and most people who have injector problems they are usually around the 40-50k miles.

If you want to PM me your email address I can send you some more info.

Are you logging regen and oil dilution on a frequent basis, ie every top up of fuel? Create a picture of whats happening on Excel in graphical form like I did.
Car Speedometer Odometer Steering part Tachometer

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Right, back to digging my veg patch over, lunch finished.
 
#152 ·
Hi guys,

All from my experience:
I don't think that starting with injectors replacement is the best way to do it.
All DPF and performance issues are mostly due to carbon build up in the intake, which eventually may lead to injector failure (wrong air / diesel mixture)
I would start any diagnostings with EGR blanking and check regen frequency again. It is 10 minutes job, just some food can sidewall with 2 holes to match bolts (drink cans are not thick enough). It will show "engine icon" on the dashboard, but it make no influence to car performance during the testing.
Then I would clean up carbon build up in intake manifold + surroundings and sensors.
And just then start worrying about injectors - they are expensive compared to mentioned tasks.
I've cleaned 3 different Sky 2.2 and believe me or not - disabling EGR and cleaning intake helps in all cases. Example pics with 4 year old car and 46k miles on it at the time.
Example pics attached and this is not the worst I've seen, did not trigger any errors yet. Biggest problem is shown on pic 1, where EGR gases joins fresh and not so dry air (a lot of oil particles from engine breather and turbocharger) pumped by turbocharger.
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#154 ·
Hi guys,

All from my experience:
I don't think that starting with injectors replacement is the best way to do it.
All DPF and performance issues are mostly due to carbon build up in the intake, which eventually may lead to injector failure (wrong air / diesel mixture)
I would start any diagnostings with EGR blanking and check regen frequency again. It is 10 minutes job, just some food can sidewall with 2 holes to match bolts (drink cans are not thick enough). It will show "engine icon" on the dashboard, but it make no influence to car performance during the testing.
Then I would clean up carbon build up in intake manifold + surroundings and sensors.
And just then start worrying about injectors - they are expensive compared to mentioned tasks.
Derrecky,

It is illegal to blank off the EGR valve in Europe, it is there for a purpose.
These Skyactive diesels are not meant for a diet of school runs, sat idleing or shopping trips, but long distance runs at a steady 70mph, then you don't get intake blockages.
When I had mine de-coked on the inlet side for free by Mazda it wasn't too bad they said.
Depending what symptoms and reading you are getting then you can tell if the injectors are failing, namely increase in sump dilution and rising sump level and frequent regens whose frequency is dropping and both of these are to be monitored using Forscan with hard numbers not guesses.
It eventually gets to the point that code P243C:00:2F comes up which means too many regens in a certain mileage, then your injectors do need changing.
I know, I went through this and the dealer didn't know it was the injectors.
Carbon build up in the air intake has no effect on the operation of the injectors.
Read my other posts regarding injectors and DPF's choking.
 
#153 ·
Hi people, i have the same issue... ,
-First my car is mazda 3 1.5d from 2016.(135000km)
-have a p0471 code error freeze in odbii but i dont have motor light up on dashbord.
-dpf light up on dashboard.
-regen 30-50km.
I will come back to have your expertize and opinions on what i can do with some data.
My mazda center tell me that is the injectors but i dont think so..
Thanks to all
 
#155 ·
In Spain you have a lot of examples of only motorway usage and carbon build up in the intake. Not only city driving is creating that carbon, at 70mph the EGR is open at around 45% and that means carbon at the intake.
Intake cleaning is not so expensive as injectors replacement.
Also injectors seal washers is a common defect in these engines and are easy to replace and inexpensive.


Mazda6 SW MK3 2.2D
 
#158 · (Edited)
Javier, removing carbon on your intake system and the problems caused by faulty injectors are completely separate, doing either won't correct the others effect.
With a blocked intake manifold there is more chance of the dash lightingup like a christmas tree.
Agree but injectors are not the only option.
In example, in addition to Exh.pressure no.1, the Differential pressure sensor is likely to have a big influence.

Mazda6 SW MK3 2.2D
 
#159 ·
Sternchallis have you considered the option, that clogged intake makes burning process inefficient due to wrong air/diesel mixture, creating even more carbon build up, raising the temps in burning chamber and damaging injectors and their washers as well? Otherwise how can you explain that all injectors failed, never 1 or 2?

To see christmas tree on dashboard due to clogged intake, there has to be almost no airflow through it. I've seen one (1st pic on my previous post) where overall air passage was smaller than a pinky finger, car behaviour was terrible (could not accelerate linearly, regens every 60-70km) and yet - no light on the dashboard. Just proper carbon cleanup fixed the issue, no hiccups, regens every 200-250km. And it drives fine for the last 2 years.

As javier.g mentioned, steady motorway rides loves carbon build ups - EGR is open most of the time.
 
#163 · (Edited)
Derracky,
Yes I will give you that point that insufficient combustion air will give poor combustion.
In fact on a large diesel engine ( same engines they used for the QE2 Diesel conversion) I experienced this. Started with poor fuel, lack of water washing the gas side of the turbocharger ( we were running on 3500 sec Redwood, almost tar in comparison to auto diesel). We had exhaust valves burning out and one inlet valve. But no effect to injectors. The gas side of the turbo was choked with heavy carbon (which we removed with water and washing up liquid). So yes bad combustion. On those large enginesj there was no MAF or MAP fitted.
Now as far as the bad combustion affecting injectors and the copper washers I would say No. The older high compression diesels ran at higher temperatures and it was unusual to have to remove a fuel injector. In fact my last car a Rover 45 Tdi had never had its injectors touched in 104k miles.
Mazda injector seals is another problem entirely.
As the cylinder head is alloy, the injector pocket quite a thin construction they cannot put too much pressure on the injector shoulder where the copper washer fits. It seems they got the material wrong for the washer and its now alloy or tin coated copper. They tighten the injector down in a sort of rocking motion of the bridge, such that one nut is backed off and the overall torque on the nuts is very low, and they use a screwdriver handle type torque wrench say 20Nm. Its abit of a faff rather than just pulling them down evenly until tight, one of those things you learn by experience, but no in this case.
I don't know about long runs clogging the exhaust up, but on any car you go on a long run say 200 mile , fully loaded, the engine gets hot and any carbon and deposits tend to fall off and the car feels quite free, be in a diesel or a petrol.
You might be only turning 1800 rpm at 70 mph in 6th, but the load on the engine is the same from Newtons Laws of Motion. You need to burn a certain amount of fuel and air to give you the power to drive at 70 mph. The engine is just turning slower the higher gear you are in. Fixed speed, fixed rpm but variable fuel input as you reach hills up or down.
With injectors, the faults range from blocked holes in the nozzle, lift pressure too low or high, jammed pintle, worn holes causing poor combustion , dripping injector resulting in high exhaust temps and overfuelling, poor combustion.

I will have to have words with my SM and try and get a steer on the job for No1 Exh pressure sensor and what alarm code would trigger it. But don't hold your breath.

Dealers are not equipped for testing fuel injectorss and know very little about them.
In my case it was Mazda UK that diagnosed the problem from some poor images, which meant it was a foregone conclusion. New injectors produced improved readings all round without a 2nd inlet decoke. Driveability before or after didn't change, just fuel consumption and oil dilution rate.
 
#162 · (Edited)
Javier,
You have Exh pressure sensor 2 which is the one with two rubber pipes near the fire wall just left of centre, this gives the differential pressure across the DPF which flags up when its clogged up and the one that initiates the P243C code.
The Exh Pressure sensor 1, which is the one you showed located middle of the engine, perhaps in the exhaust manifold is called Exhaust Pressure Differential Average. One time on mine No. 2 was 0.2 psig and No.1 was 0.3 psig.
Is this sensor before the turbo charger or after.
No.1 never came up when I had injector problems causing fast filling of dpf. So what that sensor tells you I don't know.
A blocked inlet will have no effect. A blocked exhaust possibly, but why two sensors.
Read my reply to Darrecky I am just about to write rather than me repeat. Interesting discussions though, but do the dealers really know how these engines work and what each sensor is for, I don't think so. They follow a troubleshooting chart that came from Japan and fit part A or B, but don't test the old part or are able to logically troubleshoot, they are just part fitters.
 
#168 ·
For sure Bulgaria is in Europe, not so sure about UK though, as it seems it do not want to be in Europe anymore. A lot of old Soviet block countries have better qualified technicians than UK for sure for simple reason - there are much more old, abused (with unknown history) cars which requires much more effort to be fixed. In UK there is no fix culture, just replacing everything which seems to be a problem because computer (or service manual) says so. Change this, that, if that wont help it's not our fault, you need to pay for it anyway.
Car MOT procedures are same here and there as well, for diesels there is only smoke test, no NOx test at all. Otherwise there is no way to find out any EGR mods, and if engine is tuned properly it can't detect DPF removal as well.

And no, Mazda DPF algorithms are not set to (quote) "the engine to run as clean as possible to meet the regulations for clean air" as there is PM_GEN pid which forces DPF regen after fixed amount of diesel burned even if filter is half full. That is definitely not environment friendly feature.
 
#170 ·
We have a similar tread on forscan forum : Mazda CX-5 2.2 SkyActiv-D - DPF filling fast - FORScan forum

Regarding all of this regeneration process, I think that mechanics don't know either what can cause a frequent regeneration, except if there is a very clean reason. For DPF filling fast issue, many times the cause is bad (one or more) injectors. You can't see anything wrong on the tester, but one of injector could spray a little more fuel , so that means that there will be a rich combustion => extra smoke => faster filling of DPF.

The other thing is carbon or soot building up in intake manifold which is obviously a disease of mazda diesel engine :( The cure is that from time to time (depends of driving pattern) we clean the intake manifold - i will do it before i reach 90.000km and see what the situation will be. MAP is always dirty, i know a few colleges from our forum, they have ideal driving patterns, and still have this sensor full of soot.. :)
 
#171 ·
Due that mine old Mazda 6 GH 2012 was completely crashed with any circumstances I wasnt involved and aware of 4 weeks ago just bought nice Mazda 6 Gj 2.2D AT 175HP 2016 and then my story begins....I was so happy with old Mazda 2.2 D 163 HP with DPF , never ever fuckin problem 214000 km without any problem. And now when I just bought new Mazda Im crying. After second week I just get P2043 DPF light.... I did colpulsory dpf regen with computer. Helped for 2 weeks , then again second time ... and now just trigerred 3
Always on highway , always after trip 250 km or more always at 6 gear (D) 120 km/h . That auto just killed me beacouse Im searching and searching and everyone just dont know what to do?
Anyway what I see is everyone only guessing.
Maybe
1 Sensors
2. Injectors
3 Clogged DPF itself
4 EGR?
5 Turbo?
It possibly means check every fu... part of this crap and still no one get solution?
My old Mazda get average fuel usage at 4,5 l D 4.5 at highway 5.6 at city with range of 1100 km at 65l tank . New Mazda 10 l at higway regen almost all the time in the city I even dont wanna guess but mostly I can do 660 km range . Yesterday I did again parking regen dpf and calibrate injectors / learning . Fuel usage better at 4.8 l at higway with average of 55km at 6 l /100 km.
Distance since last regen 70 km . Old Mazda 6 gh 650 km .. I just dont understand how the fuck from evolution from zoom zoom 2.2 to skyactive 2.2 things could even worse????
Im making 55km each way higway riding per day so totally 110 km per day . I dont know how other/ previous owner did use auto..... And what should I do just first time I dont know where to start?
I get oil dilution at 171 g from Forscan . Oil i just changed last Friday. After one week i got additional oil level triggered on second dot ...... (was between 2 dots when I chnged)
This is all drama ......... I just red 3 forums about this , no solution whatsoever :cry::cry::cry::cry:
 
#174 ·
On my mazda 6 i have the same problem as above. It has 85000 km on the clock, and within 2 fuel tanks everything became very strange. PM_ACC_dsd parameter is rising fast, causing the regeneration interval to be halfed :( I don't believe that injectors became bad within 2 fuel tanks, the most suspicious part would be EGR itself.
This happens to be in my case the same - but i am not sure if this is the cause:
"When the engine is warm, EGR_C_BP_ACT (EGR cooling bypass valve) should be = 0%. This is the inaccessible EGR, which is still closed after heating. But EGR_C_BP_ACT shows me practically still a value of 0.39 - 0.78% after heating, even if the requirement is EGR_C_BP = 0%. This is said to cause the filter to clog quickly, they told me at the service station. "
 
#175 ·
Has anyone took their egr off, considering it myself as when I monitor it's parameters using forscan it'll often jump to values above 100%, which must surely be impossible, and sometimes display error instead of a %. Have seen a workshop manual description for removal but that asks you to drain the radiator and everything which I don't fancy doing if I don't have to
 
#176 ·
My 6 has been treated with cleanings of both egr valves and intake manifold. It was almost for 0.5l of sooth, intake manifold was full of sooth, apart from other components (egr) whereas there was not so much of sooth at all. I will see if this will have any impact on PM parameters.
Today after a short drive, the parameters was like this:
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Usually PM_X_DSD was starting to overtake PM_GEN when PM_GEN was around 1-2 g/l.

That is the last screenshot before intake manifold cleaning:
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#177 ·
My auto just came back from the dealer in Netherland . They took out the DPF filter for cleaning . It was only 66% full. They aDAPT SENSORS AND SO ON BUT STILL EVERY 40 50 KM regenerations are triggered. What its frustrating that pm accumulation value rises after regenerations slowly from 0 then 0.1 0.11 0.12 after every km I made constantly and then after its in 1 second from 0.14 grows to 4.80?If it will be constantly growth then the car should have this 500 km cycle but due to fault from sth its trigger this regeneration mode.I record two movies when it happens . In my car after one cycle of regeneration 3 g dilution of oil come on board . So I have change oil every 5000 km to avoid to much oil dilution ??? WTF????I have dealer quarantie till 03.08.2022 and he asked me to try one time to do this before I try to get my money back . I really loVE Mazda but if anyone cannot find solution than what can I do more?
 
#178 · (Edited)
Hi All,
thank you for everybody participated in this discussion. There is just few comments from my side.
  • if I can remember good (read all comments in this discussion), just two members reported solved problem: one with replacing of injectors and one with cleaning of intake from soot. This is maybe conclusion of discussion, what can be in practice?
  • injectors can be, very logical, source of problem: spraying not so fine fuel fog in cilinder, burning can be so clean, and DPF can be clogged fast. This is just considering, at there can be material damage or dirtiness - both can cause the same results. There are few fuel holes on injectors - some of them can be clogged. In one post, if I remember good, somebody claims that injection time was too long - this can be consequence of some clogged holes. This kind of injectors can't be repaired, but can be cleaned (without dismantling)? This is discussion for some diesel specialists which can try and test - even so detailed testing can be challenged. But I can remember, that somebody tested old injectors and was bad on test - this give chance to discuss even more, what was bad, precise, and how this parameter changes after cleaning.
  • consequence of dirty intake can be unequal air quantity distribution between cilynders AND abnormal swirling of air in cylinder. This can cause bad and sooty burning. Unfortunatelly, ECU can check average quantity of air by MAF sensor, but can't see difference between cylinders.
  • I believe that Exhaust Pressure Differential Average is just average value (filtered) of Exhaust Pressure Differential, because second one is fast changing (pulsations in exhaust), and this can be main signal for evaluation of clogging percentage of DPF (together with some calculated flow of exhaust gases). If you looking for refference values, just define first at which conditions this need to be measured. Maybe this is enough good defined in this discussion: at idle, 2000 and 3000 rpm in place, engine on working temperature. But pay attention, that if EGR valve is not in the same position for all vehicles where you will compare this parameter, or fresh air flow is different by strong clogged intake, exhaust flow can be different, and diff. pressure wil be different for the same state of DPF... this is little bit tricky, but probbably enough good for first estimation.
  • don't be angry on dealers: oftenly, service documentation give not accurate and detailed data for precise diangostic. Moreover, control range for parameters are to wide, missing description of parameter meaning, how they are calculated, where can be used, what mean too big or too low value, how to check futher... I like to read description of DPF regeneration algorithm in detail, to understand what and why happens - but I don't believe that Mazda dealers has this description in own service instructions. Even fault code conditions are not explained - I saw it just one time on some old Hyundai service instruction. Sometimes, on trainings, there are chance for ask more, and if they are happy to have really good teacher, with a lot of experience in maintenance and development (!!) of these systems, service technicians can learn more (and stay in touch in case of necessary support). Service owners don't like to have engineers employed for diagnostic purposes. This costs. It is easier to change everything what they think that can be cause - customer will pay everything, with or/and without good results. Until this practice will be not changed, workshop owners will be do it on the same manner. You pay "working hours" - spent time, NOT good results. Good results are not in offer (price list)... you ordered what is offered. Let's think about workshop with diagnostic engineer employed - are you sure, that you are ready to pay ca. 500 EUR (for example, in average) for precise and reliable diagnostic? (+ for repair)
 
#180 ·
Hello,
Just want to share my story if someone could find it useful.

I have 2014 Mazda 6 driven now about 416 000 km and those kilometres driven mostly by me, so I have owned this car already for years and so quite familiar with it.

The car has original DPF and never done anything (wash or clean or else) to it. Usually my interval between regens was between 240-400km, but about six months ago, it suddenly went to around 160km.

I read this topic and decided to try replace the exhaust gas pressure sensor and so bought the latest improved version of that and replaced it by myself. (Same time I replaced vacuum pump as error code for it came 5 times within couple weeks, but this shouldn't have any effect on regen intervals.)

I didn't reset any learned values of the gas pressure sensor after replacement.

First I thought it wasn't helpful as didn't see any significant effect on regen intervals, but now after about 5 or more regens, the inteval has improved every time. Last one I had today was 330km and before that it was 300km so it seems it's getting better cycle after cycle.

So, my point is that this sensor can be one reason for too short regen interval, but of course it can be something else as well.
 
#181 ·
Hello, Just want to share my story if someone could find it useful. I have 2014 Mazda 6 driven now about 416 000 km and those kilometres driven mostly by me, so I have owned this car already for years and so quite familiar with it. The car has original DPF and never done anything (wash or clean or else) to it. Usually my interval between regens was between 240-400km, but about six months ago, it suddenly went to around 160km. I read this topic and decided to try replace the exhaust gas pressure sensor and so bought the latest improved version of that and replaced it by myself. (Same time I replaced vacuum pump as error code for it came 5 times within couple weeks, but this shouldn't have any effect on regen intervals.) I didn't reset any learned values of the gas pressure sensor after replacement. First I thought it wasn't helpful as didn't see any significant effect on regen intervals, but now after about 5 or more regens, the inteval has improved every time. Last one I had today was 330km and before that it was 300km so it seems it's getting better cycle after cycle. So, my point is that this sensor can be one reason for too short regen interval, but of course it can be something else as well.
Wow that's some massive mileage. If it's not a typo that's 260,000 miles in 8 years! Are you still on your original injectors? Have you had the EGR, cooler or inlet manifold cleaned? Are you still on your original cam chain? If so that's pretty amazing!
 
#183 ·
What would happen if you either disconnect both rubber hoses to the differential pressure sensor or just the electrical connector?

Would this stop the sensor starting a DPF regen or would try and do one all the time? I suspect it would throw a DTC and warning light.

If it worked then the DPF regen would only be triggered after each time 17.1 litres of fuel have been consumed.
 
#184 ·
What would happen if you either disconnect both rubber hoses to the differential pressure sensor or just the electrical connector?

Would this stop the sensor starting a DPF regen or would try and do one all the time? I suspect it would throw a DTC and warning light.

If it worked then the DPF regen would only be triggered after each time 17.1 litres of fuel have been consumed.
You'd get a DTC and check engine light.
 
#185 ·
Hi Everyone, I am having the exact same problem with my 2017 Mazda 3, 1.5. Did replacement fuel injectors sort this long term for those who took that route?
Long backstory of rising oil levels, excessive black exhaust smoke (caused by rising oil levels), a new DPF fitted that pretty much immediately blocks again followed by limp mode, TPMS & traction lights ultimately ending now with the car not starting.
 
#186 ·
How many thousand miles or kilometres has your car done and what is the car mainly used for (short, long journeys or a mix?).

4 injector fitted and coded at a Mazda dealer costs 2000 Euros +. You can buy cheaper unknown quality ones on eBay but these will still need testing and coding.

Was your DPF terminally blocked and if so at what distance? Could it not have been cleaned? Are you using Forscan or another program to monitor the build up of particulate matter and distance between DPF regens.

It might be worth trying to find a diesel injector specialist to test your old injectors spray patterns and check for cavitation!
 
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