DPF cleaning temperature

[Ashaz]

Hi,

Apologies for asking this as I'm sure it's been asked before but a search here and on Google doesn't tell me.

 

What is the minimum engine temperature needed to burn off the soot on a DPF?

I'm assuming it can be done with a certain temperature for 40mins, a higher temperature for 30mins, a higher temperature again for 20mins etc.

Thanks.

 

 

[Urrell]

Top of the list in a Bing search.
https://www.snapon.com/diagnostics/uk/news-centre/technical-focus/dpf-hints-tips#:

Edited 6 September, 2020 by Urrell

[Ashaz]

Thanks, I must give Bing a go.

 

However, the temperatures don't bear any resemblance to the only ones I see in the car, ie it is rare to see a temperature reading above 100C (oil).

[Urrell]

It's not the engine oil temperature that burns off soot it's the exhaust temperature.

[Ashaz]

Yes, but I would never know that from in-car readings.

Is there a VERY rough conversion from the oil temperature to a likely exhaust temperature?

 

Basically, would an oil temperature of 70C have any effect? 80C? 85C?

[SuperbTWM]

The engine temperature has no connection to DPF temperature

[Ashaz]

Shame. It means that I have no way of knowing if driving at an oil temp of 80C is having any effect.

[SuperbTWM]

2 minutes ago, Ashaz said:

Shame. It means that I have no way of knowing if driving at an oil temp of 80C is having any effect.

 

Its having no measurable effect whether its 80, 90 or 100, what makes the DPF hot is fuel* (diesel)

 

*in the case of an active regen

Edited 6 September, 2020 by SuperbTWM

[Urrell]

If you have an OBD11 reader and smartphone VAF DPF app gives you all information.
The screenshot here was with a cold engine, the DPF changes colour when it is regenerating.

[Ashaz]

Thanks all.

I don't have an OBD11 reader so I guess it's just back to getting everything as hot as possible whenever possible.

The lockdown played havoc with my DPF with lots of only small, slow journeys.

[Urrell]

2 minutes ago, Ashaz said:

The lockdown played havoc with my DPF with lots of only small, slow journeys.

If you cannot see that without something like VAG DPF that is free and an OBD II scanner about £15 how do you know ""The lockdown played havoc with my DPF""?
Are you getting warning lights on the dash?

 

[Ashaz]

Are you getting warning lights on the dash?

 

Yes, but I want to stop it getting to that stage.

[J.R.]

You dont need to "get everything as hot as possible" it will make no difference, a regen will not initiate before the engine is up to operating temperature, it wont happen any quicker or better if its hotter than that, but hey if you really believe that it will then you might as well drain out half of your coolant and engine oil.

[Ashaz]

4 minutes ago, J.R. said:

You dont need to "get everything as hot as possible" it will make no difference, a regen will not initiate before the engine is up to operating temperature, it wont happen any quicker or better if its hotter than that, but hey if you really believe that it will then you might as well drain out half of your coolant and engine oil.

 

That pretty well answers my question.

[Urrell]

7 minutes ago, Ashaz said:

Are you getting warning lights on the dash?

 

Yes, but I want to stop it getting to that stage.

If it is that bad does it have reduced performance being in safe mode?
It will not reduce the soot much even when up to temprature, it,s when and active regen kicks in that that happens.

 

[J.R.]

I have shared your anxiety, pre lockdown when I was rebuilding mine it got started and ran many times & tried regens, I left it idling for long periods but it still brought up the dash warning, one 20 min journey and it was sorted and never returned.

 

Car has been with me here in France since lockdown began and only did short & infrequent journeys but it did not repeat and I never heard it regenning, now I do a 10 mile each way return trip 3 times a week and another 3 very short journeys & all seems fine.

[Ashaz]

Urrell

There was no noticeable difference but according to the lockdown rules I could drive if I had a valid reason so I concluded that to keep my car working and potentially save £££££ on a new DPF I was ok to drive up and down a dual carriageway until the warning disappeared.

 

[pist0nbr0ke]

 

The irony

[OldBoyScout]

5 hours ago, Ashaz said:

I was ok to drive up and down a dual carriageway until the warning disappeared.

 

Check your Owners Manual and make sure you are revving the engine according to the instructions. A dual carriageway is a good place to do a regen. This is from my Octavia manual, but the instructions for your Yeti will be the same or similar:

 

In order to clean the diesel particulate filter, and where traffic conditions permit, the vehicle should be driven at an even speed of at least 60 km/h at engine speeds of 1800 - 2500 rpm for at least 15 minutes or until the warning light goes out with the 4th or 5th gear engaged (automatic gearbox: position S).

 

6 hours ago, Ashaz said:

Yes, but I want to stop it getting to that stage.

 

The best way to stop it getting to that stage is to avoid short journeys. Anything else is just as lightly to make things worse. Any fuel used unnecessarily is a waste and will add to the amount of soot already in the DPF. Just allow the car to do its thing and it may do an active regen of its own accord if the soot has reached a certain level and the conditions are right.

 

 

[Ashaz]

I saw the manual but wondered if driving a bit slower/cooler for longer would have an effect, ie the minimum oil temperature to get regen but it sounds like it doesn't work that way.

And it's not always possible to do regular high speed/revs journeys for whatever reason.

And, re. the manual, why not 6th gear?

[Llanigraham]

5 minutes ago, Ashaz said:

I saw the manual but wondered if driving a bit slower/cooler for longer would have an effect, ie the minimum oil temperature to get regen but it sounds like it doesn't work that way.

And it's not always possible to do regular high speed/revs journeys for whatever reason.

And, re. the manual, why not 6th gear?

 

Because if you are in a lower gear you are reving the engine more and therefore making it hotter.
You need to be able to keep the revs OVER 2500 rpm; I thought it said that in the Handbook!

[OldBoyScout]

4 minutes ago, Ashaz said:

And it's not always possible to do regular high speed/revs journeys for whatever reason.

 

This is just what you should do if and when you get the DPF warning, otherwise no particular need to drive like that.

 

 

[Ashaz]

You can do that on a dual carriageway in 6th gear.

Or even in 2nd or 3rd gear around town.

But I think I know the rules better now except the temperature I can see myself to start the regeneration.

[Ashaz]

1 minute ago, OldBoyScout said:

 

This is just what you should do if and when you get the DPF warning, otherwise no particular need to drive like that.

 

 

I want to avoid getting to the point of the warning. I understand that that is pretty serious. 

[OldBoyScout]

3 minutes ago, Ashaz said:

I want to avoid getting to the point of the warning. I understand that that is pretty serious. 

 

It is only really serious if you can't clear the warning, and then all is not lost as you would go to a dealership or other garage to try a forced regen.