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  • MilesDriven

Petrol Particulate Filter (PPF/GPF/OPF)

The 2018 introduction now has widespread application. Are we better off?

Mechanics and consumers have been drawing battle lines for years as cars grow in complexity to include features that are more marketing than utility, it has spawned a love and hate on both sides, especially when big bills arise. Mechanics would usually prefer easy access to parts with exposed connections. The type that is easy to wrap a wrench around, the majority of consumers on the other hand prefer a tidy layout with everything tucked away out of sight. Potential buyers also enjoy gimmicks and ‘new’ features, which are usually a pain to service or change for mechanics.

That said, the Diesel Particulate Filter (DPF) garnered hate from both sides from inception. An expensive part that technicians forever had to look at as annoyed customers came back wanting to know why yet again, they were in ‘limp home mode’. The solution used to be simple, either it was blocked from driving too few miles, all at a steady pace and so they were directed to a salesman to look at a petrol, or a day on the ramp was booked in for the car to be left running through a cleaning process. Both answers annoyed owners, and dealerships didn’t enjoy having a car on the ramp for hours running through a cleaning cycle, or having to brave negotiations of moving them into another car under the accusations of mis-selling. In defence to both sides, consumers didn’t ask for DPF’s and salesman are there to guide, not tell, people what to buy. I have first hand experience of recommending a petrol, and watching that same person a week later shake a colleague's hand on a diesel. A knuckle-wrapping followed from the sales manager for not snagging the sale a week earlier. Compounded by the fact that losing a sale means losing out on the one thing salesman turn up to work for, money. Very few customers ever appreciated that saying ‘this one would be better’ puts your own income at risk, instead plastering a smile across your face and nodding is the order of the day. Four months later the customer returned, on a tow truck. Worse of all he had kept my card, beginning to lay blame at my door, he quickly realised the name in his hand was not the salesman he had bought from, but the one that had warned of this exact scenario. No apology for dragging my name through the mud up to that point, or acceptance that maybe he should have listened. On a more positive note, that customer was the exception, not the rule. Many happy customers left cheerfully, thanking the first person of the day that had offered advice, rather than a flat sales pitch. How many returned to do the deal, not as many as I would have hoped.

Enter from left of stage, the Petrol Particulate Filter (PPF). Here to do the same job as the diesel version, but in theory, up for an easier life due to the difference in emissions caused by burning petrol. Immediately though, there is a problem. In fact, there are two problems.

The first is simple, adding an additional filter onto a small engine that is already having its efficiency squeezed is bound to have some negative outcomes. Most likely, blocking. To be clear, larger engines with a higher flow of exhaust emissions, and smarter computers may have a better time, and not cause the owner much issue. These are usually bought by people at a lower risk of blocking them in the first place. The filter must get up to temperature at a constant speed to ‘self clean’. I cannot remember how many times I said that in the past, all I know is, I didn’t hear any complaints from them.

The greater concern is the same customers that blocked their DPF’s so quickly. They are usually low mileage drivers who like to be smooth and steady, the car rarely going past the first half of the rev range and only making short trips. The previous advice was, buy petrol, now, I suppose, an electric car will be the suggestion.

The second problem is the more widespread issue. All of us, at some point, will have seen a diesel car in front put a boot full of acceleration along a motorway, or fast A road, and then a big puff of black smoke. Then it's gone. We all drive past and it dissipates, we forget and move on. The pollution DPF’s were designed to reduce is released, albeit reduced and ‘cleaner’. The ability of this filter slowly degrading over time. Then they clog, or they are treated. Several years later, the third or fourth owner limps to a garage and is told that a very expensive part needs changing, you may see where I’m going with this.

Having spent some time working in vehicle parts, you get used to hearing ‘I’m not paying that.’

The filter, after a 100,000 has given up, the owner takes one of two routes, pays up, accepting that it won’t pass its emissions testing without it, and there is a reason it exists, or remove it and take their chances. Anecdotally, I can say it's just over half that replace the part, a straight bit of metal pipe can be cut up and fitted at a tenth of the cost.

The concern is, manufacturers are answering a problem for the emissions regulation to sell a new car. Once it is out on the road, their responsibility for emissions cease. You may think, at least I have a warranty on a new car, but don’t be so sure that will save you. These are filters, if it blocks in your ownership, the warranty claim for a new part could well be rejected due to ‘improper use’. A term that I have heard shouted across a dealership by customers many times by pale faced service advisors growing ever paler by the second. It’s usually followed by rather scathing remarks about all motor dealers, sadly, selling something and building it is rarely separated in the publics mind.

The answer, we need to limit emissions, this we can all agree on. A simple solution would be for the regulations to not just cover the point of sale. Instead, manufacturers are liable for replacing or fixing these filters as long as the car is on the road. Taking emissions seriously by offering up huge restrictions is a blunt instrument answer. Car engines age, in doing so they lose a bit of efficiency and power, and so burn a little more fuel, add in a filter on its last legs, and the Co2, along with the other nasties, will never match the shiny new car fresh off the line.

It may be time that manufacturers spent a little more time talking about lifetime emissions, rather than point of sale. Maybe this time will be different, perhaps the PPF has got an advantage of years of research on its diesel counterpart, and it will last forever.

Global pollution is a problem, maybe we should start looking at other fuel options instead of trying to strangle an engine. Electricity will step in to fill these shoes at some point but let's not kid ourselves, the internal combustion engine will still be going strong in twenty years. Mass adoption of EVs still relies on public acceptance, government infrastructure, and critically, cost. They aren't called 'rare' earth metal for no reason, making batteries in the hundreds of thousands may not necessarily see a huge slip in price depending on what technology and materials come next. First-hand experience of the first tells me ICE’s will be here for some time ahead, the second point guarantees it.

London may become a Mecca of charge points, but a nationwide roll-out, flash forward to government debate 2030, the argument will be rolling on.

Not only would making manufacturers responsible for lifetime emissions be fairly easy to enforce, emissions are checked on every MOT or yearly check that may apply in whichever country you live (with some notable exceptions). If a car failed this emissions check and wasn’t modified, the manufacture foots the bill. Overnight the effort to make these filters last a lifetime would increase. Catalytic converters should fall under the same legislation, ensuring their design is optimised. Customers wouldn’t then need to worry about a four-figure bill, lurking under their car, waiting to spring up with nothing more than an innocent check light on the dashboard. Some people will choose to modify the systems for freer flowing ones, and as long as they fit in the tolerances that’s perfectly acceptable, the manufacturer can be let off the hook.

Whilst we’re there we should probably talk to people about taking better care of the complex systems that manage emissions, sadly this is a much harder job. In motoring journalism, it is sometimes forgotten that our readers don’t represent all consumers. Enthusiasts generally quite enjoy an hour checking the car over. Many of you reading this may already be aware of how to take good care of your car or eager to learn, unlike the average buyer that looks at a car with the same excitement as a washing machine. The plumber is probably getting called out right now for them, better understanding leads to better care. The regulators should remember that when driving for a cleaner future.

While we're there, could we have some sensible exemptions made, the aftermarket will always provide for those that want to extract more horsepower. Some sensible limits for emissions for the ‘hot’ variants whether they are hatchbacks or motorway munching executive speedster. This should keep people from just cutting everything off and putting a straight pipe in its place. The ‘track only’ sales of exhausts are likely to go through the roof otherwise.

Check out our article entitled 'Heavyweights' for more on electric vehicles or our 'winter drive in a diesel' to hear whether heavy oil has finally had its day in light passenger vehicles.


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