Understanding DPF Regens

[Optimus prime]

I did read somewhere that a low fuel level can also inhibit the regen cycle?

Not sure if that's what the Golf logic works like though?

Yes correct you must have at least 1/4 of a tank it forms part of the regen criteria like a lot of cars

[mcmaddy]

We just need more English data files in vcds now 

[fredgroves]

BTW, I think understanding the system logic behind the regen cycle is useful information - I've had oil burners for years, but never really truly understood how exactly this works.

That the "mad fan" is a post-burn symptom is interesting for example.

[p3asa]

Yes correct you must have at least 1/4 of a tank it forms part of the regen criteria like a lot of cars

I never knew that. Some folk only ever put £10 to £15 in of fuel at a time. They will be causing all sorts of problems.

[itavaltalainen]

Had a look with VCP on oil ash level today.... at 75k miles I am at 26.8g. DPF limit being 80g, which means that it should last for another 150k miles. 

[Optimus prime]

Had a look with VCP on oil ash level today.... at 75k miles I am at 26.8g. DPF limit being 80g, which means that it should last for another 150k miles. 

Yep looked after I would say that's possible.  Bmw used to say check @120k but they phased it out when the LCI cars came out with a combined cat & dpf fitted closer to the the engine bay.  I did read about a 3ltr Bm doing 225K on the original dpf and that was on a 2007 car.  Technology has moved on a lot since then as well.

[itavaltalainen]

Nah you can abuse it As long as you only drive long distances you're OK
What really seems to kill them off is short journeys.

[Rhyso]

Nah you can abuse it As long as you only drive long distances you're OK
What really seems to kill them off is short journeys.

What really kills them is people's ignorance to the warning lights 

My A3 PD170 had the DPF in for 50k, nearly 20K of which was mapped miles and for the first 18 months did a round trip of 8 miles per day with the occasional blast in between. I never once saw the DPF light or even had the car doing an active regen (revs never increased when sat stationary)

[Optimus prime]

Regen criteria is similar for most derv cars & the MK7 is no different.  See below these factors what are typically looked for by the ECU before it starts the process:

1.  Over 1/4 tank of fuel
2.  ECT over 70C
3.  Speed about 40 mph

Obviously the process will only start if the soot loading requires it to.  If monitored by VCDS you can expect to see the temps before and after the DPF hit 600C+ during a full dpf regen.

Typically it is very short journey's (without a long run once a month) and the fact that the ECT never reaches above 70C that causes issues.  Also the lack of knowledge regarding the dash light

This is just a rough guide but for those that only do 2 miles a day and always run on less than 1/4 tank of fuel I would consider other options or a little more house keeping with regards to the way you use / drive your car

[Rhyso]

Another trigger is the pre-turbo temps need to be above 700C to activate a regen 

Good luck doing that in 4th at 40mph as per the handbook