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I am classic MG fan of 35 years standing. I decided to add to the 'fleet' ('B' & 'TF') with a brand new ZS. Soon after taking delivery it was apparent that the car had an intermittent running fault which I described as being like a 'misfire'/timing problem. I returned the car to the dealer to rectify but was told that they didn't need to drive, or even look at the car, because they knew about the fault on that particular model. I wrote down the key parts of the conversation:
The automatic version of the MGZS is fitted with a particulate filter to the catalytic converter which burns off deposits when the car reaches a certain temperature ('Regeneration'). The service chap said that when he first experienced the fault himself on a pre-inspection delivery assessment, he thought 'this isn't going too well'. He said that the fault couldn't be fixed, nor could he offer advice as to when it would happen nor for how long. I asked him to check and he came back and confirmed that the manual version did not have the filter. I was subsequently told that the regeneration process takes power from the electrics - which would fit with the symptoms.

I don't expect a £17k car to drive like a BMW or even VW and am happy to put up with other issues but this fault can go on for 25+ miles and over the weeks has become wearing.

I would be keen to hear from other ZS Auto owners (cars built from 2018).

Thank you for reading, JB
 

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PPF only on Direct injection engine cars

It is a shame to hear that you are having issues with the car at such an early age, I had a similar issue with the 1.5 litre engine in my brand new 2018 model ZS where it would constantly stall when trying to move off from a standstill. The problem eventually got looked at by the dealer and the issue has almost gone away so there is hope that SAIC/MG can find a solution for your issue.

The engine is designed by Opel and is based on their Small Gasoline engine:

https://en.wikipedia.org/wiki/GM_small_gasoline_engine

The engine is a direct injection model which is supposed to reduce CO2 but has been found that it isn't as clean as it was thought to be which is why they have had to install the Petrol Particulate Filter (PPF) which is also known as Gasoline Particulate Filter. My own ZS SUV has an indirect injection based engine which is why it does not need to have one fitted.

The filter if it is like the diesel version should regenerate when it gets hot enough, this is done passively however the following should be noted:

Gasoline particulate filters (GPF) have been introduced to reduce particle number emissions from GDI vehicles. The filters utilize wall-flow substrates first developed for diesel particulate filters. The GPF regenerates passively, but an active regeneration assist is needed to prevent filter plugging during low temperature duty cycles. Ash has an impact on GPF performance and—if the GPF is coated with a three-way catalyst—can be a source of catalyst poisoning.

In your case it could be that there is a blockage or if there is a sensor it could be misreading something during the active regeneration.

The above information about active regeneration on PPF's can be found here:

https://www.dieselnet.com/tech/gasoline_particulate_filters.php

Cheers..
 

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More information about PPF's

Gasoline particulate filters
Engineering for lower vehicle emissions

Regulations curbing vehicle tailpipe emissions are being introduced and/or tightened the world over to help improve air quality. Insight looks at the automotive industry’s growing use of gasoline particulate filters as one method of compliance.

Although figures vary widely, recent data suggests that every year air pollution causes more than 5.5 million people to die prematurely worldwide. The main culprit is reported to be the emission of small particles from power plants, factories, vehicle exhausts and from the burning of coal and wood.

In vehicles, the small particles are largely made up from soot, which results from an imperfect mixture between the fuel and air prior to the combustion process. To a lesser extent, lubricant and fuel derived hydrocarbon residues can also form particles.

Particulate emissions limits
Regulations in several countries have been introduced to limit the emissions of these small particles from vehicle exhausts. In the European emissions standards, diesel vehicle particulate mass (PM) limits have tightened from 0.14 g/km in 1992 for Euro 1 to 0.005 g/km in Euro 5 and 6, which resulted in the deployment of diesel particulate filters (DPF).

Particulate emissions were not initially regulated for gasoline engines since conventional port fuel injection (PFI) engines do not emit a significant amount of particulates. However, gasoline direct injection (GDI) engines, have become a key technology - enabling CO2 emissions to be lowered while improving torque and power output. But, they are reported to emit more of the smaller more concerning particulates compared to conventional PFI engines.

Consequently, in 2009, the Euro 5 standard introduced PM limits for gasoline vehicles although, at this point, only diesel vehicles were regulated for particulate number (PN). For Euro 6, PN limits are being progressively phased in for gasoline engines, with the initial 6x1012 #/km value being replaced by 6×1011 #/km in Euro 6c for GDI engine, which took effect in September 2017.

While the latest GDI engines can achieve the lower PN limit in the conventional (NEDC or WLTC) regulatory test cycles, Euro 6c introduces a Real Driving Emissions (RDE) test procedure, which will include particle counting in a wide range of engine map operations. In addition, cars will not only be tested in controlled chassis dynamometer tests but also in real life conditions by using Portable Emission Measurement Systems. Whatever conditions are defined, RDE will introduce larger ranges of temperature, engine load and other variables.

In addition to European regulations, we are also seeing tough emissions limits coming into force in India and China.

From January 1 2017, National V limits, equivalent to Euro 5, came into force nationwide in China. In India, Bharat IV, equivalent to Euro 4 will apply nationwide in 2017 and from April 2020 the Euro 6 equivalent, Bharat VI, will be introduced for all new vehicles nationwide.

Particulate filter technology
DPFs have been used to cut particulate emissions from diesel vehicles for many years.

As particulate limits are extended to GDI vehicles, we can expect gasoline particulate filter (GPF) technology, which has been developed by building on the experience gained with DPF, to be used more widely in new vehicles.

GPFs look very similar to DPFs and, generally speaking, work in a similar way. The filter has a honeycomb structure, usually made from cordierite, a synthetic ceramic, with alternately sealed inlet and outlet channels. The exhaust gas is forced to flow through the porous filter substrate, which traps the soot. At about 200 to 350 channels per square inch, the canal density of the GPF is nearly the same as a DPF. The major difference between the two types of filter is that the porosity of the GPF is higher because the substrate is lighter. Although this allows the gas to move more easily across the substrate, it also means the GPF is more fragile than a DPF.

Generally, the GPF is integrated in the three-way catalyst (TWC) downstream of the normal substrate, which then becomes a four-way catalyst. An alternative is to keep a TWC close to the cylinder head and introduce a 2nd four-way catalyst under the flooring.



Regeneration
Particulate filters are very efficient - reported to be able to remove more than 90% of particle emissions. However, this efficiency presents a challenge. Over time, soot builds up in the filter which, if not removed, results in increased backpressure. The best way to remove the soot is by burning it off in-situ in the presence of oxygen and at temperatures >600oC; a process known as regeneration.


Unlike diesel engines, where oxygen is in excess, gasoline engines generally run at stoichiometric mixture, which means there is no oxygen in the exhaust to burn off the soot when the engine is under high load.

Consequently, for gasoline engines, regeneration can only be effective for non-power conditions and so is performed under deceleration, when the engine is being motored, which results in oxygen being pumped though the engine. Another major difference in gasoline engines is that the regeneration is passive, i.e. there is no need to purposely increase the exhaust temperature.

To initiate regeneration, the catalyst converter is fed with air for short periods. This oxygen, combined with high exhaust temperatures (400 - 700°C), leads to soot ignition. Where engines operate for long periods without deceleration, for example driving on a traffic-free motorway without any downhill slopes, engine control is required to initiate regeneration. In this case, the exhaust temperature is increased by delaying the spark timing and oxygen is made available by creating a lean fuel/air mixture.

A full DPF can contain around 8 grams of soot per litre (g/l) at which point active regeneration is needed. For the cordierite GPF substrate, the filter capacity is around 1 g/l. However, this small storage capacity is not really an issue since particulate emissions are some 10 to 30 times smaller in mass for GDI than for diesel engines and passive regeneration is very frequent.

Automotive market
GPF are increasingly being introduced to the vehicle line-ups of various OEMs.

Mercedes reports that GPF has been used successfully for more than two years in its S 500, where the architecture is a twin exhaust system with a two-way catalyst coupled with a GPF in each branch. Mercedes has also announced that in 2017 further S-Class variants, with the new M 256 and M 176 gasoline engines, will be equipped with this technology. The filter will then be gradually introduced in other new vehicle models, face-lifted models and new engine generations. Eventually, the OEM says it plans to use GPF in the current model series. The automaker reports it is investing a total of about three billion euros to ensure further improvements in fuel consumption and emissions – in both future and current vehicles.

In 2016 the Volkswagen Group announced that all Group direct injection TSI and TFSI engines would be fitted step-by-step with GPFs to reduce emissions of fine soot particles by up to 90%. The process started in June 2017 with the 1.4-litre TSI engine in the new Volkswagen Tiguan and the 2.0 TFSI in the Audi A5. Implementation is then following in further models and engine generations. By 2022, The Volkswagen Group says seven million of its vehicles could be equipped with this technology annually.

The PSA Group has also announced plans to include GPF in its direct injection gasoline vehicles. They report that their technology offers 75% higher efficiency in terms of the number of particles captured. Already available in the 1.2 litre, three-cylinder turbo PureTech gasoline engine, by the end of 2017, the automaker says the filter will be rolled out to all PSA Group direct injection gasoline engines, on both three-cylinder turbo engine families and four-cylinder models. PSA says these engines are being upgraded on this occasion to increase performance and output, and thus increase fuel economy even further.

Volvo has been reported to say it could introduce GPF to meet emissions targets, but it is also looking at increasing its use of electrification of the powertrain. The OEM says it sees electrification as a more cost-effective way of meeting legislative targets, especially as the price and performance of the components come down.

Future updates
As OEMs test GPF aftertreatment systems in their engines, it remains to be seen if the technology will result in any changes to future industry and/or OEM lubricant specifications and engine tests.

It looks very likely that, as PN emissions limits are more widely introduced, GPF use will extend across vendors serving the European, Chinese and Indian markets.

Infineum is monitoring GPF introduction and maintaining a continuous dialogue with OEMs to assess the impact of lubricant formulation on GPF performance. We will share the outcomes in future Insight articles.

Source URL:

https://www.infineuminsight.com/articles/passenger-cars/gasoline-particulate-filters/
 

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Trouble is all this stuff doesn't work work in the real world. DPF's constantly block up and the petrol ones as used on the BMW NOx etc are the same causing the motorists huge repair bills. Also the direct injection engines have huge problems with carbon built up on intake valves due to that and the complexity to the fuel systems again cause unnecessary bills and don't provide a huge gain in fuel consumption.
 

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With a response like that from the dealer, I would be asking for my money back - poor show.
 

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Discussion Starter #6
Huge thanks to those of you above who have taken the time to respond. Much appreciated. However, saga goes on...........
 

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Huge thanks to those of you above who have taken the time to respond. Much appreciated. However, saga goes on...........
Does the auto gearbox allow you to use it with engine braking as this would cause the engine to rev more which could in turn heat up the PPF and allow it regenerate?

On the diesel ones, owners were advised to drive their vehicles in a lower gear/higher revs which would normally help the regeneration process.

It could also be that the engine is learning your driving style and you might need to have the adaptations reset so that it can re-learn your driving style from scratch again.

I have had this done by the dealer when my own ZS 1.5 litre was going through the phase of constant stalling at junctions when pulling off.

Cheers..
 

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Trouble is all this stuff doesn't work work in the real world. DPF's constantly block up and the petrol ones as used on the BMW NOx etc are the same causing the motorists huge repair bills. Also the direct injection engines have huge problems with carbon built up on intake valves due to that and the complexity to the fuel systems again cause unnecessary bills and don't provide a huge gain in fuel consumption.
I wouldn't expect a petrol GPF to be anywhere near as troublesome and a DPF. A petrol engine has much higher exhaust temperatures in general use and requires less changes to the timing or using the egr valve etc to raise the exhaust temp like a diesel would.

Also petrol engines don't produce any where near the amount of soot buildup a diesel does. So the filter won't fill as fast as a diesel one and the resultant Ash left over will also be less as there is a less soot being burnt off and turned to Ash.

That's in theory obviously.
 

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ZS surging intermittently

My 9 month old ZS Exclusive Auto has also been misfiring (or surging) on a regular basis so I finally took it in to the dealers that have just opened in my area. Because they were new to MG they were not aware of the fault and gave it a thorough going over but finally came to the conclusion that nothing could be done as it was a ‘feature’ of the gearbox which could not be rectified, to which I replied that ‘I would consider it more of a fault than a feature’! They totally agreed but were powerless to do anything about it. If they told you it was due to reaching a certain temperature, I can dispute that as mine can be perked in the garage for a couple days and it starts as soon as I start my journey. Then I can drive 3 to 4 miles with this fault, park up for a couple of hours, get back in the car for the return journey and no problem at all. My fault is very intermittent and a complete mystery as to when and why this is happening. Sometimes it can be 2 weeks between faults. I am not a happy bunny and am hoping that if enough people complain, it should become a recall situation. I really hope you all agree.
 

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Discussion Starter #11
My 9 month old ZS Exclusive Auto has also been misfiring (or surging) on a regular basis so I finally took it in to the dealers that have just opened in my area. Because they were new to MG they were not aware of the fault and gave it a thorough going over but finally came to the conclusion that nothing could be done as it was a ‘feature’ of the gearbox which could not be rectified, to which I replied that ‘I would consider it more of a fault than a feature’! They totally agreed but were powerless to do anything about it. If they told you it was due to reaching a certain temperature, I can dispute that as mine can be perked in the garage for a couple days and it starts as soon as I start my journey. Then I can drive 3 to 4 miles with this fault, park up for a couple of hours, get back in the car for the return journey and no problem at all. My fault is very intermittent and a complete mystery as to when and why this is happening. Sometimes it can be 2 weeks between faults. I am not a happy bunny and am hoping that if enough people complain, it should become a recall situation. I really hope you all agree.
Thanks for your response Lynn. It seems we have the same problem and the courtesy car they loaned me for 12 days was the same aswell! There must be others..........
 

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I've owned my mg zs for 4 months bought her from new in the 1st couple of weeks I noticed something wasn't right but it didn't happen all the time. so it gradually became worse so phoned dealer took her in they did some update said all would be fine took her to work today I'm a florist so use the car for deliveries it a great size. 3 weeks since they did there update have been noticing same problem again went to do delivery and she wouldn't go over 3000rpm so I now have a courtesy car thanks to mg Assistant and fingers crossed that my new car can be fixed with no further issues
 

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I am classic MG fan of 35 years standing. I decided to add to the 'fleet' ('B' & 'TF') with a brand new ZS. Soon after taking delivery it was apparent that the car had an intermittent running fault which I described as being like a 'misfire'/timing problem. I returned the car to the dealer to rectify but was told that they didn't need to drive, or even look at the car, because they knew about the fault on that particular model. I wrote down the key parts of the conversation:
The automatic version of the MGZS is fitted with a particulate filter to the catalytic converter which burns off deposits when the car reaches a certain temperature ('Regeneration'). The service chap said that when he first experienced the fault himself on a pre-inspection delivery assessment, he thought 'this isn't going too well'. He said that the fault couldn't be fixed, nor could he offer advice as to when it would happen nor for how long. I asked him to check and he came back and confirmed that the manual version did not have the filter. I was subsequently told that the regeneration process takes power from the electrics - which would fit with the symptoms.

I don't expect a £17k car to drive like a BMW or even VW and am happy to put up with other issues but this fault can go on for 25+ miles and over the weeks has become wearing.

I would be keen to hear from other ZS Auto owners (cars built from 2018).

Thank you for reading, JB
[/QUOT
Hi I have a 69 plate ZS 1L Auto which has only done 1600 miles and I've had from new we had a cold spell about 2 months ago and had the same problem. Took it back to dealer and mechanic came for a drive with me he told me it was because it had not gone through its full regen as it was not run in yet.they kept it in and they told me they had forced it through its regen and done a software update , this seemed to have worked but first time we had really cold wether since then and its misfiring again. Not contacted dealer yet as I want to get more information so they can't fob me off with more B.S any advise would be grateful.
 

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Hi I have a 69 plate ZS 1L Auto which has only done 1600 miles and I've had from new we had a cold spell about 2 months ago and had the same problem. Took it back to dealer and mechanic came for a drive with me he told me it was because it had not gone through its full regen as it was not run in yet.they kept it in and they told me they had forced it through its regen and done a software update , this seemed to have worked but first time we had really cold wether since then and its misfiring again. Not contacted dealer yet as I want to get more information so they can't fob me off with more B.S any advise would be grateful.
 

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We've a Jan 19 plate Exclusive Auto that has been misbehaving all week - I noticed at the weekend on the motorway (fully warmed up) it was pulsing slightly - cruising at 70(ish) I could feel the car hesitating/pulling. Today my partner took it to work, and told me at one point it would neither brake or accelerate and he had to use the handbrake in traffic to make it stop. He also revealed for the first time, that he regularly switches off the stop-start feature when it switches on because it usually will fail to start again. I'm contacting the dealer to have a look but all of the above sounds quite familiar.
 

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Hesitation and or pulsing is quite normal when DPF equppied vehicle is doing a regeneration. So it also figures that petrol with a PPF will also exhibit the same scenario. It can be very slight or very pronounced dependant upon the soot and or Ash loading of the filter. It seems many people assume soemthing is a fault when it is actually a trait of that type of engine using a particulate filter.

It doesn't help when garages can't explain this properly to an owner.

It sounds totally normal to me unless it is happening all the time in which case it's likely down to a clogged filter that juts can't burn off the soot.

Engines have moved on a lot and most people don't know about or even understand DPF's let alone PPF's which I wasn't aware were a thing until fairly recently.

As for the comment regarding not being able to brake or accelerate that is not normal, regeneration will not affect the braking system and won't stop the vehicle accelerating either.
 

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This is what is letting MG down.

Lack of support from both the Dealer and MG direct. If they want to build up their business they need to look after people and say it a characteristic of the car in this case and in the rust cases.

Just hold your hands up and deal with it appropriately and people will appreciate that they can try the aftercare
 

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PPF only on Direct injection engine cars

It is a shame to hear that you are having issues with the car at such an early age, I had a similar issue with the 1.5 litre engine in my brand new 2018 model ZS where it would constantly stall when trying to move off from a standstill. The problem eventually got looked at by the dealer and the issue has almost gone away so there is hope that SAIC/MG can find a solution for your issue.

The engine is designed by Opel and is based on their Small Gasoline engine:

https://en.wikipedia.org/wiki/GM_small_gasoline_engine

The engine is a direct injection model which is supposed to reduce CO2 but has been found that it isn't as clean as it was thought to be which is why they have had to install the Petrol Particulate Filter (PPF) which is also known as Gasoline Particulate Filter. My own ZS SUV has an indirect injection based engine which is why it does not need to have one fitted.

The filter if it is like the diesel version should regenerate when it gets hot enough, this is done passively however the following should be noted:

Gasoline particulate filters (GPF) have been introduced to reduce particle number emissions from GDI vehicles. The filters utilize wall-flow substrates first developed for diesel particulate filters. The GPF regenerates passively, but an active regeneration assist is needed to prevent filter plugging during low temperature duty cycles. Ash has an impact on GPF performance and—if the GPF is coated with a three-way catalyst—can be a source of catalyst poisoning.

In your case it could be that there is a blockage or if there is a sensor it could be misreading something during the active regeneration.

The above information about active regeneration on PPF's can be found here:

https://www.dieselnet.com/tech/gasoline_particulate_filters.php

Cheers..
The 1.5 unit in the ZS, is not the Gm unit, but MGs own. The 1.5 in the GS and HS is the GM unit. completley different engines.
 

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The 1.5 unit in the ZS, is not the Gm unit, but MGs own. The 1.5 in the GS and HS is the GM unit. completley different engines.
Hi, I don't think anyone mentioned that the 1.5 litre NSE Plus (Atkinson Cycle) non turbo engine in the ZS is the same as the SGE turbo engine from GM. The fact that I mentioned that the SGE uses Direct injection whereas the 1.5 litre engine in my own ZS uses Indirect injection, we aren't talking about the same engines at all.

This why the NSE Plus does not need the GPF/PPF which seems to causing a lot of 1.0 litre auto owners a lot of issues at the moment.

I only mentioned my experience with MG regarding the 1.5 litre NSE engine because when it was first released, it was a potential death trap where the engine would mysteriously cut out when pulling out at junctions, leaving you as a sitting target to being hit from the right hand side.

Thankfully, this issue has now been sorted and it is hoped that SAIC MG will devote enough engineers to sort out this issue rather than just devote their time to the new 5 star NCAP rated vehicles in the the form of the ZS EV and HS.

I have read elsewhere that SAIC MG managed to resolve the issue with the sleep charge problem of the ZS EV in about a month and an update for the stupid bongs associated with MG Pilot is also in the works yet there is nothing mentioned about helping the 1.0 litre auto owners getting the GPF/PPF problem resolved.

Given that the engine is GM sourced, if the issue was as bad as it looks then surely Vauxhall cars using the same engine would be seeing the same issues?

It might also explain why SAIC MG have the new 1.3 litre SGE engine lined up with the facelifted model in China.

Cheers..
 

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It sounds totally normal to me unless it is happening all the time in which case it's likely down to a clogged filter that juts can't burn off the soot.

Engines have moved on a lot and most people don't know about or even understand DPF's let alone PPF's which I wasn't aware were a thing until fairly recently.

As for the comment regarding not being able to brake or accelerate that is not normal, regeneration will not affect the braking system and won't stop the vehicle accelerating either.
Thanks - I've been driving it the last week and the hesitation thing seems to have stopped. As for the breaking/acceleration issue - I'm convinced it was a case of big foot (you think you're braking but you're also pressing the accelerator too) the other half denies it, but I can't think of any logical explanation as to why or how this could happen given brakes and accelerator are totally different systems.

We still won't use the stop/start as it's lethal - the number of times it leaves you stranded 2/3 feet out of a junction is just plain dangerous. I've had varied experiences with stop/start from one manufacturer to another, my 2019 Mercedes C200 is not that great either - lumbering into life rather slowly but the MG is by far the worst! I can cope with hesitation but when it just half starts then dies that's a bit rubbish! Will be having a word with the dealer at service time.
 
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