I used to work for a well known supermarket driving HGV's into Central London.

The "(desk) driver trainers" used to insist that you kept below 2,000rpm (the on-board telematics would grass you up if you did !).

That meant you had to amble away from the lights holding up other traffic.

Stick with that & you would return to the RDC with a dashboard like a Christmas Tree & it would go into a forced regen meaning the vehicle had to be left outside, engine running for up to an hour.

I never stuck to it & never, ever had an HGV go into regen &/or restricted performance.

I could never understand the logic behind this.

Diesels are designed to work - just ask any HGV (or large diesel) engineer.

Hard working a diesel engine on acceleration does not clear the DPF on passenger vehicles and infact quite the opposite it's a quick way of filling up the DPF with soot 2012 TDV8 Vogue (L322)

Right so, if that's the case. why do manual / forced regen routines push more fuel into the engine (or exhaust, if so equipped) to get the exhaust (and by default, turbo) temperatures up high enough to burn off the stored soot?

I just hope you never sell your car as some poor sod is going to have bought a real moneypit.

And yes, it's possible to get the engine core temperature up by using command shift, we do it all the time on the roads around the workshop where the limits are 30 or 40 mph and plod likes to turn up with speed detection equipment on a regular basis.

Active regeneration introduces fuel into the exhaust after the combustion cycle and closes the EGR valve to raise the temperature of exhaust gases and thus the DPF core. This is not the same as revving the engine or hard accelerating . My car has run fine for the last year / 15000 miles and I've never had a DPF full warning and my last one 2 diesels did >120kmiles between them over 8 years with also no DPF warning lights or issues. Just steady driving with plenty of motorways and regular oil changes to dump the soot load in the oil. 2012 TDV8 Vogue (L322)

EGR's are not closed during regen, otherwise the NOx values would be through the roof and the vehicle would not conform to EU5 or greater type approval. A regen (forced or otherwise) does not require greater Oxygen levels to increase the exhaust temperature, just post injection or dedicated exhaust diesel dosing injector.

JayGee wrote:

Just steady driving with plenty of motorways and regular oil changes to dump the soot load in the oil.

The EGR valve closes on active DPF regeneration according to the live data on my GAP IID ( one way of seeing it's in active regen mode) and the workshop manual. Same as on my previous diesel cars with DPF's from VAG and GM. 2012 TDV8 Vogue (L322)

Bill wrote:

JayGee wrote:

Just steady driving with plenty of motorways and regular oil changes to dump the soot load in the oil.

The new car servicing requirement is every two years … the regen is achieved at much lower speeds.

Every 2 years  2012 TDV8 Vogue (L322)

Funny that, the data I have is from VWG vehicles, using manufacturers diagnostics - EGR's definitely operate normally during regen cycles. From what i've seen on here, IID live values are not altogether reliable.
PSA vehicles (the ones that don't have an exhaust dosing injector) also operate the EGR's 'normally during regen cycles, now given that the Lion engines and their derivatives are PSA designed, care to take a wild guess about the regen / EGR strategy?
I still have some of the design / training notes so I'll see if I can find the relevant sections.

BTW, if the EGR's were closed, how much of this 'extra' oxygen do you think would make it into the exhaust?

JayGee, you proved yourself wrong when I questioned your reply earlier in this thread. I didn't know if you were right or wrong but it didn't sound right that's why I asked.
I think members should only say things that they know to be factually correct or say nothing at all.

AFAIK the workshop manual PDF is downloadable from the wiki (Exhaust section - DPF description) and it's quite a detailed description of how it operates on the 4.4 TDV8. Given the EGR gases are added to reduce combustion temperatures it would likley not aid the regen process and there is also the additional problem of circulating very hot gas into a plastic intake plenum. I guess as far a emissions are concerned the regen cycle will happen outside urban areas. 2012 TDV8 Vogue (L322)

JayGee wrote:

Hard working a diesel engine on acceleration does not clear the DPF on passenger vehicles and in fact quite the opposite it's a quick way of filling up the DPF with soot

Bill wrote:

JayGee wrote:

Just steady driving with plenty of motorways and regular oil changes to dump the soot load in the oil.

The new car servicing requirement is every two years … the regen is achieved at much lower speeds.

kevinp wrote:

JayGee, you proved yourself wrong when I questioned your reply earlier in this thread. I didn't know if you were right or wrong but it didn't sound right that's why I asked.
I think members should only say things that they know to be factually correct or say nothing at all.

I made one factual error which I checked and corrected. That doesn't mean I've 'proved myself wrong'. I agree members should only state things they know are factually correct and hence why I'm posting as there is a lot of opinions and not so may facts (IMO ). 2012 TDV8 Vogue (L322)

Kot wrote:

JayGee wrote:

Hard working a diesel engine on acceleration does not clear the DPF on passenger vehicles and in fact quite the opposite it's a quick way of filling up the DPF with soot

Giving the 2nd ~Turbo a good blow in fact helps to blow out the ash in the DPF, only the soot is burnt off during Passive or Active Regeneration. If the DPF temperature is above 250C Passive Regeneration will burn off most of any soot produced.

its possible you could be happily Regenerating, burning off all your soot, but slowly accumulating ash.