DPF's for petrol cars?

[cromwell]

A DPF being a diesel particulate filter, fitted to diesel cars to filter out harmful soot particles that otherwise come out of the exhaust.

For some reason, modern petrol engines are emitting more soot particles than the old petrol engines, and more than ten to one hundred times the amount that a diesel engine fitted with a dpf gives out. Report here
https://www.sciencedaily.com/releases/2 ... 144338.htm

and
https://www.ft.com/content/60b7cc8c-56b ... 144feabdc0

I can feel more expensive stuff coming on. More expensive parts and more expensive tax.

[TheOstrich]

I fear you're right, but I would have thought they needed to crack the electric car battery capacity / recharging facilities conundrum first in order to justify price hikes, so perhaps not in my lifetime ......

Already we're seeing a huge drop in new car sales - and far more "bangers" on the road - thanks in some part to that new road fund pricing structure anyway.

[miasmum]

Dont talk to me about DPF's My car is putting its DPF light on more and more frequently.

As far as I am aware they dont fit them as standard any more

[Suff]

mm, we had this issue with Mrs S' C8. Shortly after we bought it (after hitting 85 on the AutoRoute, a speed I'm sure it never reached in its entire 27,000 mile life), the light came on. We had our dealer dismantle the DPF and have a look, he told us it was completely clear and functioning normally. i.e. a gummed or faulty sensor.

If we ran it on expensive diesel the light would go out. However what we did was simply fill the tank with Wynns DPF conditioner shortly before MOT. The light went out for the entire life of the tank of fuel and then we simply ignored it for the rest of the year.

Depending on the mileage of the vehicle, all modern diesels have a urea bladder which is used in low speed short journeys to clean the DPF and the DPF sensor. It is supposed to last 100,000 miles in town driving scenario's. Vehicles which do a lot of idling and very short trips, can burn through this bladder in 50,000 miles. Resulting in DPF warnings.

[Suff]

It is an interesting story Cromwell. In short the quest for ever increased MPG from a petrol engine. Diesel has slightly less calorific value, at the same density, than Petrol. However Diesel is more dense than petrol per litre and therefore produces about 15% more energy when burned.

Due to emissions issues with Diesel engines, manufacturers have been trying to get more and more power from the same petrol, using aggressive turbo strategies and very lean burn with Gasoline Direction Injection. G-DI is very much like Diesel where the petrol is injected direct into the cylinder after the exhaust valve has shut, removing any chance that fuel will be pushed out into the exhaust as is common in carburettor or port fuel injected methods where the fuel air mix is sucked in from the inlet manifold.

The article states:

G-DI vehicles are found to exhibit diesel like behaviour [35], emitting high concentrations of
particles over the whole test cycle. In the case of lean G-DI vehicles a significant increase in
particle emission levels is observed whenever the engine switches to stratified mode [15,35].
240 s operation in lean mode can lead to a threefold increase of the particle number emissions
over the NEDC

In short, G-DI vehicles, without a particulate filter, emit more particles than DPF diesels and breech the Euro6 regulations which are being designed to reduce both Nitrogen Dioxide and Particulate matter. Elsewhere in the article it talks about how traditional catalytic converters cannot cope with G-DI vehicles because the very lean burn leaves too much oxygen left over which is a problem for classic CATs.

We are in a cycle where the ever increasing regulations to decrease emissions, allied to the ever increasing cost of fuel, is leading to ever more complicated engine management systems and emission control systems.

Burning fuel creates gasses and particulates. Just take some petrol and put it in a glass dish and burn it. You will be left with soot. That soot is particulate matter. The fact that Diesel has more is an issue, but no hydrocarbon vehicle fuel has none. That is the Carbon bit of hydrocarbon.

The answer would seem to be simple. Let's all go electric. Except we burn hydrocarbons for half our electric and we only have enough for what we need. Hydrogen then, that's got to be clean, has it not. Oh yes, but we use catalysed electrolysis to produce Hydrogen. To get the electrical power for which; we burn hydrocarbons..

[miasmum]

Suff, my car has Wynns in the tank now too

When the light comes on, Mr S drives it hard, about 10 miles, high revs, low gears and it goes out. I just never drive far enough to burn any diesel particulates off

[cromwell]

I wonder if anyone still has my old 2 litre petrol Triumph Vitesse?

I might try and buy it back!

[Suff]

Hmmm, 25mpg at 56mph, probably more like 18 at 70mph. Not a problem at 6 shillings a gallon, but at £5.45 it's a bit more of an issue.

Transverse rear leaf spring with wishbones though... Interesting design. Still it won't get you into the ULEZ in London next year without paying the ransom....

[cromwell]

True, but it was a good looking car in convertible form.
https://www.carandclassic.co.uk/car/C806992

The "swing axles" at the back! Oh yes, I remember them. A bit too heavy on the throttle going round a sharp bend would see the back step out very sharply. Or even braking heavily in anything but a straight line. The mk2 had proper wishbones though, I think.

Anyway, back on track. If diesels have to have dpf's because they put out a lot of soot and now petrol cars are also putting out a lot of soot, then qed petrols will probably have to have a particulate filter fitted.

So we're now in confusion with nobody buying new diesels because of new diesel taxes,(1,000 staff laid off at Jaguar Land Rover the other week) when actually petrol cars are now dirtier than diesels. So it's not too much of a stretch to see people who buy a new petrol car now thinking that they are cleaner than a diesel being similarly punished with taxes in the near future.

Confusion reigns!

[JoM]

Not totally to do with the subject but John has a company car, a diesel, and all fuel (for both work and private use) goes onto his company credit card.

He's mostly office based and he's worked out that he rarely 'spends' more than £120 per month on diesel. As his free fuel is a benefit though he's taxed on it. He 'benefits' from not having to pay out £120 at the garage each month but for that little perk he's now being taxed £202 each month.
He, like many others at his company, are ditching the fuel benefit and will in future just charge the company for fuel purchased for any site visits, airport runs etc.