Author Topic: Living with Mazda diesels  (Read 8372 times)

Offline Willpower

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Living with Mazda diesels
« on: March 21, 2016, 04:06:35 pm »
I have transposed this entire posting from the Mazda 3 forum :  Whilst of course many of the references are specific to the Mazda 3, I consider that it could well be extremely useful to members on this site.

The operation of Diesel particulate Filter is a problematic one for some motorists while others (who use their cars in suitable driving patterns) have years of trouble free use. Why keep it when it can be relatively easy to get rid of it. Is the mandatory installation of a DPF by car manufacturers just a crazy idea from some miserable jobsworth?

Unfortunately the DPF is the key technology that allows modern diesels to call themselves "Clean".

The European body which Certifies DPF technology is the VERT Association based in Switzerland. On their website at they have this to say about the prime reason for developing DPFs.

Health Concerns of Particulate Matter:
The main particulate fraction of diesel exhaust consists of small particles, size range in nanometers (20 – 300 nm). Because of their small size, inhaled particles may easily penetrate deep into the lungs and from there they penetrate into the blood, even via smelling (inhaling) they may enter the brain directly. They bind also with other toxins in the environment, thus increasing the hazards of particle inhalation. Exposures have been linked with acute short-term symptoms such as headache, dizziness, light-headedness, nausea, coughing, difficult breathing, tightness of chest, and irritation of the eyes and nose and throat. Long-term exposures can lead to chronic, more serious health problems such as cardiovascular disease, cardiopulmonary disease, and lung cancer.

Many will have seen the alarmist reporting that arose from miners exposed, in years past, to significant unfiltered diesel exhaust which prompted the WHO to upgrade their carcinogenic labeling of Diesel Exhaust. For a more balanced report  see :

Yes it is possible to remove a DPF from a car that needs one and pass the UK's current MoT 'Smoke test' as it does not currently use the expensive technology capable of measuring the nanoparticles that are then emitted. The safe level of nanoparticle emission is a currently unattainable zero. To hear some of the hysterical ranting against DPF technology you would have to believe that some people have not witnessed the improvements that have been achieved over time.

The Daily Telegraph on 13th April 2012 contained the following... Should I remove my car's diesel particulate filter?

Honest John explains why it's not a good idea to remove a car's diesel particulate filter.

Regeneration game
I have been having problems with the particulate filter on a Renault Laguna diesel. I have had it regenerated twice and now someone has suggested taking it out altogether. Various firms offer to do this, but what are the side effects?
CF, Lincoln

Removal would probably cause it to fail the latest MoT legislation, which requires all original emissions reduction equipment to remain in place.
After much reading of the published research into PM issues it is this writer's opinion that it is not just antisocial to remove them it is criminally irresponsible. Fortunately I also believe that it is possible to live with them without the worst of the reliability problems that bedeviled DPFs in years past. Those who rant against DPFs today only show how the progress that has been made since they were introduced over 20 years ago has passed them by. Nor do they seem aware that DPFs can be used successfully today by all but a tiny minority. It is time we learned to love our DPFs. I will try to show you how.

1 Shared by all
From the introduction of the high power EURO4 1.6 diesel at the 2006 facelift on all (Ts & TS2) Mazda Diesels have had DPFs fitted. The 2.0 diesel was launched as an EURO4 with DPF. When the 2.2 diesel was introduced it came with a DPF designed and produced by Mazda that aimed to be more efficient when it comes to regeneration. Mazda won an award for the design.

2 Euro4 V Euro5 To achieve Euro4 the first Generation MZ-CD 1.6 engine used a Fuel Born Catalyst (additive) to burn off the Particulate Matter in the PSA/Ford designed DPF. That EURO4 compliant DPF already exceeds the standards expected for EURO6 particulate emissions.

The DPF used in the updated EURO5 1.6-litre engine, introduced in the second generation Mazda 3, is claimed to be "Maintenance Free" It appears to use a larger oxidation catalyst to increase the exhaust gas temperature and improve particulate combustion. I do not know if Mazda are supplying their own DPF or using the next generation PSA/Ford DPF. This may enable a Mazda sourced DPF to regenerate without the use of an FBC. The newest PSA DPF uses a new design of filter and a reformulated FBC which should not require maintenance before (250,000 Km) 155,000miles.

2.0 and 2.2 diesels use a different (Mazda designed) DPF technology that does not make use of a Fuel Borne Catalyst. By including Platinum in the Oxy catalyst portion of the system Mazda have reduced the temperature at which regeneration occurs and so avoided the need for a Fuel Borne Catalyst.
When the 2.2 diesel was first introduced in the Mazda 6 the following appeared in

"…. Emissions are then treated by a diesel particulate filter that uses a unique Mazda-developed, ceramic support matrix structure, which is the first of its kind to go into production in the world. Previous diesel particulate filters converted particulate matter (PM) into CO2 by reacting the PM with the oxygen in the exhaust gas at the surface of the catalytic particle. This meant that the time needed for filter regeneration was determined by the amount of oxygen on the surface of the catalyst.

When the temperature of the exhaust gas is raised to quicken the regeneration time, then technological issues – like higher fuel usage or the ceramics exceeding their thermal resistance limit – can occur. Mazda solved these issues by using highly thermal resistant material for the ceramic monolith of its new diesel particulate filter, and designing the internal structure of the ceramic support matrix with passages for oxygen to enable a large amount of oxygen to be utilized for PM combustion. With this, Mazda has succeeded in significantly increasing the PM combustion speed.
As a result, the number of times the diesel particulate filter has to regenerate (in combined mode) is cut in half, and the time necessary for each regeneration phase is shortened by one third. For owners of the new Mazda6 MZR-CD 2.2-litre turbo diesel, this means worry-free filter regeneration and, because fewer regeneration phases are required and each takes less time, less fuel consumption overall."

So 2.2 diesel drivers should encounter far fewer DPF issues than those of us with older DPF designs.

3 Operation Issues Under "Normal!!" operating conditions the DPF will accumulate a load of trapped particulate matter gradually increasing the exhaust back pressure over a few hundred miles. That back pressure balances the input forces on the Turbo bearing. Crude removal of a Oxy Catalyst/DPF leads to Turbo failure. When sensors determine that the DPF is reaching the predetermined (50% ?) load i.e. as full as good engine performance will tolerate the ECU initiates a regeneration process during which the exhaust stream is heated to a temperature where the PM is burnt off.

3.1 Normal Regeneration When the trigger point for regeneration is detected by the ECU it waits for engine revolutions to reach a prescribed level at the correct operating temperature before initiating an active regeneration. The engine revolutions and operating temperature can be difficult to meet during city driving and paradoxically during motorway cruising especially in a sixth gear. Additional fuel is injected into the exhaust stream where it is ignited and sent through the first component of the DPF an oxygen catalyst which further raises the temperature of the exhaust stream so that it is able to burn off the PM trapped in the filter. This process should only last a few minutes (possibly up to ten minutes) and takes place usually unnoticed by the driver every few hundred miles.

3.2 Incomplete Regeneration Should the engine revolutions fall when driving in traffic or when reaching journeys end before the regeneration process completes a proportion of the unburnt fuel will find its way down the cylinder bore sides and contaminate the lubricating oil. In small quantities this is not a problem. As soon as the on road regeneration conditions are met again another attempt to regenerate will be made. If the driving pattern is unsuitable too many failed regeneration attempts will trigger a warning light when the DPF load rises too far. The Owner Manual recommends a good open road drive which should enable success, If the DPF load fails to reduce and builds to a higher level, thought to be around 75%, the warning light will illuminate so that a trip to a dealer or suitably equipped independent can enable a Forced Regeneration to be achieved in the workshop.

Mazda 2.0 DPFs are known to become permanently damaged by the EGR valve blocking open. Apparently it is   reasonably simple to check and clean it as a DIY task. (Not as easy for the 1.6 EGR mounted down the back of the engine.) There is an interesting discussion here.

3.2.1 Unburnt Fuel A continuing build up of unburnt fuel mixing with the lubricating oil is a potential problem. The increase to 15% of biofuel blended in UK diesel fuel is expected to result in increased amounts of biofuel remaining in the crankcase/sump due to incomplete regeneration as the vaporisation temperature for biofuel is higher. Reduced lubrication is one issue but the more critical possibility is the destruction of the engine. Should the sump level rise too high the CCV system becomes overloaded and ejects the oil/fuel mixture into the turbo input and hence back into the intake. Engine runaway results and unless the engine can be stalled deliberately the runaway engine will self destruct.
3.2.2 Rising Oil Levels Put simply routine maintenance requires that the owner monitors the level of sump oil so as to detect any rising levels.

Oil levels which rise too much in the 2.0 and 2.2 diesels as well as the Second Generation 1.6 are sensed and trigger a warning light which must be given immediate attention. At that point not only is the DPF at risk but the dilute oil seriously endangers lubrication. For the First Generation 1.6 engines without the 'overfull sump sensor' it is even more important to check the dip stick regularly. The 1.6 dip stick Early versions of the First Generation 1.6 dipstick had a "Plastic paddle" at the base which was able to break off rather too easily. This required the sump to be removed in order to retrieve the broken piece. Later 1.6 diesels have a design which appears improved. The 1.6 dip stick has but two marks an upper and a lower. The upper mark should not be exceeded.

On a number of occasions after servicing the oil level on these dip sticks has been found to be excessively high. Too much oil added during the service may have different causes. Incomplete draining of the sump would be a problem with this engine as residual dirty oil can lead to turbo problems, I have found one instance where an oil company published a figure for sump capacity that was too high. So if an independent garage consulted this wrong information they may have inadvertently produced the problem. The 2.0 & 2.2 dip sticks The dip stick on the 2.0 and 2.2 diesels has a third mark. An "X" well above the correct full mark. This is the point at which the over full sump can cause problems. So monitoring of the rising oil level in these engines can be carried out with some confidence. The rising oil level should not be allowed to reach the "X" mark.

4 Problem Solving Once the rising oil level is seen to have reached a significant level steps must be taken to prevent it leading to problems. Two possibilities exist. The first would be to reduce the level back to an acceptable level while the second would be to bring an oil change forward.

The following needs to be considered.

A simple reduction of the oil level would still leave fuel diluted oil in the engine with a degraded capacity to lubricate the engine. This has become a more critical consideration with the introduction of 15% biofuel blends. In a downloadable pdf file on the  Millers oils web site they point out that “Higher and Narrower boiling range of biodiesel makes it more persistent once it enters the Crankcase”. Consequently oil change intervals should be reduced.

If a reduction is to be carried out the time and distance to the next oil change needs to be considered. Depending on the gap before the oil change and the excess quantity being removed it may be considered wise to remove more than the excess and top up with fresh oil so reducing the dilution effect.

If the distance traveled since the last service is sufficient and an early oil change is contemplated it may still be wise to reduce the oil level to safe levels and avoid any problems unless an immediate oil change is possible.

The 1.6 engine especially has a reputation for blowing too much oil vapour in the CCV gases during normal use as a result of inadequate performance of the built in 'oil separator' before the CCV valve.

4.1 Reducing oil level Two DIY methods for reducing the oil level may be self evident. Removing the sump drain plug is not only a bit of a difficult and messy job but one that is not be possible without the appropriate tools and facilities.

The second method is suitable for reducing oil levels although not really suitable for a complete oil change. Most inboard boat engines cannot be given an oil change by removing a drain plug so their oil is removed by pumping the oil out of the Dip Stick pipe. A variety of mechanical suction pumps are sold for the purpose as are electrical powered ones. As the task is not too difficult or frequent the mechanical hand pumps will usually suffice. eBay or a Boat Chandlery will be able to supply. After warming the engine and switching off, the pump input tube is inserted into the dip stick mounting tube and the oil pumped out and captured in a suitable container. It is one person task.

4.2 Oil Change
In the second Gen 1.6 the 2.0 and 2.2 diesels the monitoring system should give warning when urgent action is required. Because of the critical nature of the oil level I would not rely on a sensor but inspect the dip stick regularly. The failure to deal with the problem can be catastrophic and very expensive.  Should you be concerned that rising oil levels may have destroyed the lubricating quality of your oil and be a possible cause of premature wear you can always pay for an Oil Analysis from one of the specialist laboratories or use a quick DIY test like this one. See:

5 Maintenance When an accumulation of failed DPF regeneration attempts have occurred or when the DPF is nearing the end of its normal life span the indications of unsuccessful regeneration must be dealt with. A thorough clean out of the DPF is known to be extremely beneficial. Removing the DPF and washing it with a power washer is a primitive method that can produce results although it would give the Health and Safety brigade a heart attack because of the release of the DPF detritus into the environment. Commercial services such as are available using a number of techniques although not from a Mazda dealer. They, of course, only have one option... replace with an expensive new one.

5.1 DPF Flush cleaning When presented with a limping diesel with blocked DPF garages using, the appropriate diagnostic equipment, can identify when a DPF is blocked beyond the level at which even a forced regeneration is safe. At this point a dealer will suggest a new DPF with a cost to the north of £1000.00. In almost all cases that is an unnecessary expense. The DPF can be cleaned by removing it from the car and soaking the DPF in a Flushing Liquid for at least ten hours. After which the DPF is replaced and an additive is mixed with a full tank of fuel to complete the cleaning process. ECU counters probably need resetting too.

One flushing liquid is produced by BlueChem, a German company, and marketed in the UK as 'PowerMax DPF FLUSHING LIQUID'  The Flushing product can be hard to find from specialist distributors but is available to the determined DIY sleuth. See:

5.2 Passive Regeneration Additives In order to achieve DPF regeneration the accumulating particles need to reach a temperature at which combustion can occur. Without any catalyst to lower combustion temperature the soot will need to be heated to 500oC to 550oC for that to occur. In the 2.0 and 2.2 it appears that diesel fuel ignited in the exhaust stream is used. In the 1.6, with its fuel borne catalyst, combustion is achieved at a lower temperature by a similar means.

Spontaneous passive combustion can only be achieved if the exhaust reaches a very high temperature which is not usual or a different fuel borne catalyst is used to lower the combustion temperature sufficiently to enable a passive regeneration at normal operating temperatures.

The PSA/Ford system uses on board dosing system to add a Fuel Borne Catalyst named Eolys by Rhodia the French company who developed it. Eolys reduces the combustion temperature to between 400oC and 450oC. Unfortunately we do not know which of the five or six formulations of Eolys is used in our Mazda 3 diesels. The latest generation "Eolys Powerflex" appears to be a 100% Iron oxide based product rather than the rare earth substances used previously. It is used at very low dose rates. 1.7L for 250,000km and is claimed to be more effective than earlier products. Whether it will reliably deal with DPF regeneration in all operating environments I do not know. The current absence of DPF problem reports for the second generation 1.6 Mazda 3 may be a good sign.

When faced with a need to achieve reliable regeneration in a short journey stop/start environment we diesel drivers really would prefer a spontaneous passive regeneration at the lower exhaust temperatures normally experienced. For cleaning out a blocked DPF at least three products are now available which claim to offer help. The distributors of these products have published testimonials from the Garage Trade endorsing their effectiveness in cleaning blocked DPFs when unsatisfactory regeneration processes are encountered.

One product from Clean Diesel Technologies, Inc. (CDTI) in America called “Platinum plus” by them but marketed in Europe by JLM a Dutch company as "JLM Diesel Particulate Filter cleaner" is suitable for 2.0 and 2.2 diesels but NOT for the 1.6 diesels. It is based on cerium as used in Eolys but is combined with an organo-platinum compound. It may be that using it in a 1.6 would produce a cerium overdose and cause problems. Details here h Available from several retailers and on eBay.

The second and more recent product is from BlueChem in Germany. It is branded as “PowermaX” and called "DPF powerclean" in the UK. No details on its composition have been found. It is recommended for all DPF systems. That includes our PSA/Ford 1.6 diesels using Eolys dosing. It is available from the UK distributor here and elsewhere such as eBay. The UK distributor has testimonials from a garage who has used it successfully on a Citroen and confirmed, when I contacted him, that it is safe to add the product to the fuel tank of cars with the PSA/Ford Eolys FBC system.

A third product that may deliver automatic passive regeneration is “Diesel Particulate Filter Cleaner and Regenerator”  from Forté a well established company supplying the independent garage sector. See:  The product should be suitable for 2.0 and 2.2 diesels. The manufacturer does not comment on its suitability for use with the Fuel Born Catalyst already used in the first and second generation 1.6 diesels. I would wait for confirmation before using it in those. Other products are being introduced to the market.

So if a trip to a garage to identify the cause of a problem (or a DTC code reader throws up P242F on the 1.6) you have an ash accumulation problem. Before spending big on a professional cleaning service or even replacing the DPF try one of these products at about £20.00 and thirty odd miles of driving to give it time to do its job. If you have reason to think your DPF is at risk you may wish to consider adding the additive to your fuel tank periodically, say after a service.

JLM also market a formulation of the 'Platinum plus' product especially designed as a replacement for Eolys. The JLM  product reduces the combustion temperature to around 300oC which can be achieved during normal running resulting in 'Spontaneous Continuous Regeneration'.

5.3  1.6 PAT fluid V Eolys When the time comes for a  First Gen Mazda 3 to have the FBC/Eolys tank refilled (37,500 miles) or sooner if you are encountering more than the occasional DPF blockage it looks as if it could be worth replacing the Eolys with the 'Platinum plus' product from JLM that is marketed with the catchy name of “PAT fluid”.

The cost of PAT fluid should be less for the apparently better product. A partial DIY approach is possible. You can buy the fluid and an essential 'filler kit' from some distributors including eBay. After refilling your 1.6 Eolys tank, situated under the floor  midway between the rear wheels, you will still need the ECU counters reset. That means a trip to a Bosch Service Centre (Independent garages) unless the (as yet untested) rigmarole for resetting the counters for the Ford Focus works for us too. You can find it on line or in the Haynes manual for the Ford Focus Diesels.

6 DPF Replacement When replacement of the 2.0 DPF or 1.6 combined CAT/DPF is required you can always purchase a new one through a Mazda dealer. Alternatively you can obtain an after market replacement for a much reduced cost from one of the specialist suppliers such as these.

Mazda CX-5 Forums

Living with Mazda diesels
« on: March 21, 2016, 04:06:35 pm »