DPF and fuel economy

[IN2VWS]

I have a theory, and I might be wrong or imagining it.......

Last year I was driving my T5 DSG 132kw van through a very hilly region while towing a tandem trailer with a car on it.
The engine was getting a good work out with plenty of high rev driving.
After this my fuel economy improved. I thought this is great. Never had economy like this before.

Moving on.......On a recent trip to Sydney, I decided to give the DPF a cleanout every 200km by flicking the steering wheel paddles and dropping the trans into 4th gear and driving for 1 km with the revs at approx 3800 rpm.
Once again, my fuel economy was great.

I am going to continue to do this.

Has anyone else had similar experiences? Or am I imagining it.

John

[Sunny43.5]

Not yet but it makes sense I read somehwere that the DPF will block up and then obviously for the van to maintain the peformance it will use more fuel until it regens . One theory was that as the DPF starts to block the exhaust fumes behind the filter can cause the engine to heat up more than normal as as the blockage ocurrs the engine is struggling to get the gases out and could cause the manifold to crack . I am not a fan of this myself it seems that car makers are constantly building systems that are designed to do a job but in themselves they can lead to even more problems as they can cause breakdwns as has been reported by quite a few VW owners .

[Transporter]

The regeneration process actually uses extra fuel, there is no device that blocks the DPF while it's regenerating. I give my T5 a good acceleration (0ver 3800rpm) up the hill once a day that keeps the turbo variable vanes from seizing. However, every time you accelerate more than you need to, you're using more fuel, hence more particles are created and sooner you clog the DPF. So, driving like you stall it and your DPF will have a greatly reduced life. Using right fuel additives helps to a better fuel burn and more complete fuel burn - less soot and other particles in the DPF. Frequent (unnecessary) hard accelerations when you drive will lead to more engine wear and more lubricating oil ending in the cylinder clogging the DPF.

People who drive normally (gently) have less problems with the DPF, as long as all the sensors are working correctly. However, when they never accelerate hard their turbo needs work (or replacing) much sooner, and their dual mass flywheel doesn't last as they change the gears too late.

[Sunny43.5]

After reading this from Transporter it just fills me with even more hatred of todays technology in cars , drive too slow and it clogs drive too fast and it you clog it is it me or is the DPF just another disaster waiting to happen I have heard and read of several owners whose vehicles have had to be towed because of DPF light coming on when they were driving "normally " yes we all drive long and short trips so if manufacturers cannot make something that works to suit "Every" drive then it should not be there at all . If the day comes that ours does something like this I will be the first under the van with spanners in hand and remove the bastard !! or has been done elsewhere drive a stake through the mongrels heart clear out the debris and just keep on truckin'n .

[Transporter]

Sure, in the perfect world, if something can't function 100% reliably, it wouldn't be in the vehicles, especially when it comes to emission devices. For that we can thank to the emission laws like EU5 and EU6.

However, when the DPF fails sooner than expected it comes down to the failed sensor(s), contaminated(wrong) fuel, incorrect engine oil, some performance chips (not remaps) will also kill the DPF quite fast and also driving extremely short trips like 2-3km to the bus stop and back.

[Sunny43.5]

Agree with you there Transporter some of these things are outside of our control , failed sensors ? manufacturing fault ? contaminated fuel ? oil companies with little regard for quality control [ definetley happens with petrol RON rating ] not so sure with diesel . personally i don,t remap so to speak with a chip no point for me the van goes just sweetly for my taste . Short trips well thats the one I get riled up about , not every one drives long fast trips thses days so for a van to develop a problem based on where and how its driven is to me a mistake in design IMO . Like putting a fluid filter "inside" an automatic and then tell the customer when it fails tough luck .