DPF- Hope i have the abbreviation correct....

forgotmyname

If your doing 2600rpm and need to do 3000rpm change down a gear?

GolfBravo

OddballJamie wrote: »

It's not a myth, it's in the manual of some manufacturers. If you only do short trips with a diesel fitted with a DPF then forced regen is something to have to do and live with.

Manuals refer to assisted regeneration, i.e., when the warning light(s) comes on - most diesel drivers will never need to force regenerate a DPF.

And usually manuals refer to keeping revs above 2000rpm (VAG, PSA/Ford/Volvo) and driving for at least 20 minutes at main road/motorway speeds. IMHO "over 3000rpm" is way over the top, as most diesels are redlining at 4500rpm anyway.

Forced regeneration is when the above fails and you need to take the car to a garage - the car is then hooked up to a diagnostic tool. PSA/Ford/Volvo forced regeneration takes 3500rpm for 20 minutes (preferably outdoors, as the DPF gets red hot).

Forced regeneration YouTube video.

CKhalvashi

I changed the EGR in a '52' plate Scenic for someone a few weeks back, trip computer went from 34mpg when I was trying to work out what was wrong with it, to 52mpg on the same route when I was working out if it was right.

£180 cost, plus 2 hours of my time, it's faster and it's already recouped that cost in fuel.

I red line my car on a motorway slip road once a week to keep the DPF cleaned out (it's diesel auto, so I can't do this on the motorway), and I've had no problem with the engine yet (currently upto 56000 in 10 months)

The fuel cleaner is another good idea, and I put 2-3 tanks of 'normal' diesel in the car, then a tank of 'performance' diesel, all of which seem to work. Mine's a 275ps twin turbo engine, so probably one tank in 10 will do the same on most engines.

CK

GolfBravo

CKhalvashi wrote: »

I red line my car on a motorway slip road once a week to keep the DPF cleaned out (it's diesel auto, so I can't do this on the motorway), and I've had no problem with the engine yet (currently upto 56000 in 10 months)

The fuel cleaner is another good idea, and I put 2-3 tanks of 'normal' diesel in the car, then a tank of 'performance' diesel, all of which seem to work. Mine's a 275ps twin turbo engine, so probably one tank in 10 will do the same on most engines.

CK

Diesel soot in DPF is not the problem - it easily burns out during the regeneration cycle. The main problem is ash.

Ash in DPF comes not from fuel but from (mainly) oil additives, and also from engine wear and corrosion - there are some trace elements in fuel that eventually end up in the DPF, but they are in insignificant quantities. So redlining your diesel in fact increases engine wear and oil burn, therefore it slowly kills your DPF. Premium fuel with fairy dust doesn't make any difference to DPF, changing oil regularly and treating the engine nicely does.

Retrogamer

If i ever end up with a modern diesel with a DPF i'd blank / remove the EGR valve, have the DPF removed and the ECU modded to ignore the EGR & DPF readings.

Less things to worry about, and you gain some throttle response.

Ultrasonic

Retrogamer wrote: »

If i ever end up with a modern diesel with a DPF i'd blank / remove the EGR valve, have the DPF removed and the ECU modded to ignore the EGR & DPF readings.

Less things to worry about, and you gain some throttle response.

I can't understand why removing a DPF hasn't been made an MOT fail condition. There is no logic to only allowing cars to be sold with them to meet emissions standards but to then not do anything about owners removing them and thereby no longer meeting these standards.

I would be worried about removing a DPF from a car in case their removal was subsequently made illegal.

Ultrasonic

GolfBravo wrote: »

You can help it by increasing the engine load, not revs, by putting it in high gear and giving it some berries at low revs - don't need to keep it above 3000rpm, normal revs will do (around 2000 is fine).

Surely the point is that by running at high revs in a lower gear you can maintain high load for a long period of time. You can't do this by 'giving it some berries' at low revs in a high gear as the car will accelerate.

jase1

Engine doesn't 'like' running at 3000 revs? Hmmm.

(Goes to check engine on jase1's car which is routinely driven at 5-6000 revs. No, it's still there).

GolfBravo

Ultrasonic wrote: »

Surely the point is that by running at high revs in a lower gear you can maintain high load for a long period of time. You can't do this by 'giving it some berries' at low revs in a high gear as the car will accelerate.

According to PSA and GM/Fiat engineers high gear/low revs + berries method is more effective. The car will obviously accelerate, so you will need to take your foot off the accelerator, but you don't need to keep the high revs for the regeneration to work. Short bursts of acceleration and load ensure that the exhaust gas gets really hot fast. But since the ECU takes care of everything, you shouldn't really have to do anything - just drive.

The reason why manufacturers suggest motorways speeds to generate load is due to aerodynamic drag, and not due to higher engine revs - drag is proportional to the square of speed, so the faster you go, the higher the engine load regardless of revs.

PS
I've seen some eye-opening white papers re: DPF. It really is a can of worms, with significant environmental issues (regenerations, DPF remanufacturing, Eolys serum, production, etc.). And I thought fluorescent light bulbs were bad.

GolfBravo

jase1 wrote: »

Engine doesn't 'like' running at 3000 revs? Hmmm.

(Goes to check engine on jase1's car which is routinely driven at 5-6000 revs. No, it's still there).

That's how modern diesels get driven these days - below 1500rpm most of the time. They just need a new DMF and forced DPF regeneration every few months.