Would it really be that difficult?

[Fraczish]

As I sit here (again) waiting for my DPF regen to finish I can't help but wonder, would it really be that bad an idea for the car to suggest that it requires a regen and give you the option of performing it or not? If not selected within a certain time/distance a regen automatically takes over. It just frustrates the life out of me how it always seems to know when your about to pull up at home or just popping to the shops....

[RickTT]

Thing is, once you stop and the engine hit idle the regen will more than lilkey stop and the fan you hear running is just trying to cool things down..

[dstev2000]

There are a list of prerequisites for a regen to start. Oil and coolant up to full temperature for a predetermined amount of time amongst others. This prevents the regen cycle initiating during a quick run down to the chippie.

Many times I've got out and heard the fans running at full tilt after a 2-3 hour drive home from work. This is my 3rd DPF car and they've all picked their moments well!

A green DPF dash symbol to show a regen in progress would be nice, but given the amount of owners who don't RTFM I'd expect that to be more trouble than it's worth, same for the option to trigger the regen cycle.

Interrupting the regen isn't harmful as long as the car has the opportunity to complete it on the next decent run. As I say, I'm on my 3rd one now and I've done a combined 200,000+ miles with no DPF problems at all.

[Fraczish]

Today my car attempted yet another Regen, after less than five minutes from stone cold, water temp wasn't half way up the gauge and the oil temp wasn't even registered. I didn't have time to allow this to finish as I was on a short hop to the hospital. Fantastic timing as always, goes to show that the car does not wait until it fully up to temp before attempting a regen.

[FelisBengalensis]

The car will look after itself and there is no need to wait for it to finish. These systems are clever enough to know how and when to run, and if it doesn't finish this time, then it will have another go the next time the engine runs and the computer sees the right parameters.

The DPF is in the exhaust so does not necessarily need the engine & coolant temps to be all the way up, just the exhaust gas temperature. The ECU controls fuelling to ensure the EGT meets and stays within limits.

If you constantly do short journeys then that will kill a DPF but otherwise let it do its thing. Sitting with the engine idling because the fans are running isn't going to make any difference, just use more fuel at low rpm and that could make things worse. The chances are that at even a fast idle the regen may have stopped anyway so all that is going on is the cooling cycle to stop the car burning.

[muddyboots]

The car will look after itself and there is no need to wait for it to finish. These systems are clever enough to know how and when to run, and if it doesn't finish this time, then it will have another go the next time the engine runs and the computer sees the right parameters.

What he said ^^^

[Fraczish]

So idiling doesn't allow a regen to complete? Learn something new every day! Thanks chaps

[cnc]

Just turn it off and leave it, it will be fine. I've always done this with mine and never had any problems at all. Except for people saying why is it making that noise (fans running) or what is that smell (soot burning off).

[blahde2]

I drove from SW Erblassen to Belfast via Holyhead in one sitting on 26 Dec. 70% of this was motorway but as outside temp was low the conditions might not have suited a Regen attempt to be triggered.

With only engine stopped only for the boat crossing, I noted a DPF Regen in progress only at a non scheduled pee stop on drive up from Du line to Belfast. I left car running (lights off in the noisy car park), ran in did my business essay and resumed my drive north.

To assist the Regeneration cycle on resumption on my drive north, I altered my usual ECO driving style and absolutely nailed it (in sport mode) up to 80mph to bring the exhaust temp back up into the right temp zone.

Shortly after I disregarded the Navs suggested route home and headed B Road over the hills. 3 minds longer overall and much less fuel efficient, but lower overall speeds, less high-speed windflow in through the radiator grill (to cool everything down), more steep inclines and slow fast slow driving meant plenty of heat being generated for the regen (if it were still in progress or not).

Engine oil temp got as high as 116°C, so I definitely made her work hard lugging a fully loaded boot up the hills.

This is my 6th car with a DPF, only the 1st Gen Golf Mk5 PD170's ever gave me bother. As most have said above, unless your driving is short and low speed you should leave or to the car to sort out.

All I would say is that if you notice a regeneration in progress, (say at the traffic lights, start stop doesn't trigger as normal and engine idle is sitting at 1000rpm) asked your driving to assist the process. Accelerate just a wee bit faster than normal (especially up hills), change gear at higher rpms and avoid 6th if able to do so (until idle rtns to norm). All this should aid the Regen cycle and cause you fewer issues in the future.

[blahde2]

I write way way too much, apologies everyone!

Edited 30 December, 2016 by blahde2

[skidpan]

Had 2 cars with DPF's (neither VAG) and con honestly say that the manufacturers recommendations did not include higher revs and faster acceleration during a regen. Both suggested a steady cruise between 1500 and 2000 rpm for approx 20 minutes but my in my experience driving at approx 1800 revs allowed the regen to complete quicker. Regens also completed on a 20 minute drive form Tesco on a stop/start ring road with a max of 60 mph and no chance of rapid acceleration.

 

One knowledgeable diesel professional explained to me that high revs can actually prevent a regen completing. Reason was simple and logical. Higher revs = higher exhaust gas speed which can prevent the DPF reaching the 600 degrees a regen needs. Moderate revs allow the DPF to heat up which is why manufacturers suggest a sensible rev range during a regen.

[Speedman]

Hi, linked to this topic, I have just installed an app from google play store called VAG DPF it claims to be able to tell you the status of the DPF. Will plug the OBD II in later and try it.