Hey

 

So I travel once/month to the  north and back (460 mile round trip) 

I also do a 12 mile round trip, to work and back, and usually some 2 mile round trip to Subways and back...

 

Any way, it seems that once/month the DPF light comes on, so I head up on the M4

 

The thing is.. the manual says do 60Km/hour (40Mph) in the third/fourth gear betweeen 1500 and 2200 RPM
 

 

If I head on to a motorway, would it not perhaps be wise to do 70Mph, and keep it in 5th gear, until the light goes away? I've just given it a run before.. I've also bought some DPF cleaner.. I dont know if it will help. Might be snake oil stuff... Who knows.

As long as you can keep the throttle steady and engine revs around 2200rpm it will regen.

I used to find 50-60 in 4th seemed to get the job done better,

 

my thoughts were that the lower engine revs and more air flow over the DPF at 70 in 5th didn't allow it to reach required temperature properly

There isn't really an issue with temperature. Post combustion injection can ramp the exhaust temp up with relative ease.

I used to find 50-60 in 4th seemed to get the job done better,

 

my thoughts were that the lower engine revs and more air flow over the DPF at 70 in 5th didn't allow it to reach required temperature properly

higher revs doesn't necessarily mean more heat in the DPF.

 

In a higher gear at a higher speed at a slightly lower RPM the engine will be loaded up more with the turbo doing more work = more heat in the DPF

 

I find 70mph in 6th will regen my Superb fine on my short run to work and as Tech1e says, post combustion injection can enable heat in the DPF in less than ideal situations such as town driving with ease. As long as you are driving for a good 10-15 minutes after the engine has warmed up the modern CR engine with DPF seems to be able to cope no matter what the driving conditions

Edited 3 April, 201610 yr by SuperbTWM

Hmm that could be why my DPF keeps coming on... ie: going to work takes me around 10 minutes or so... So Im confused now

 

Should I do 50-60Mph in 4th gear or
70Mph in 5th? - both between 1500 and 2200 RPM?

A 10min run won't be doing the DPF many favours.

Hmm that could be why my DPF keeps coming on... ie: going to work takes me around 10 minutes or so... So Im confused now

 

Should I do 50-60Mph in 4th gear or

70Mph in 5th? - both between 1500 and 2200 RPM?

I would say try both and see which suits your car best, mine was the 4th gear option seemed to give a longer time between regens

 

also learn the signs of an active regen (increased idle rpm - about 1200rpm, strange rubbery / eggy smell if doing active regen when you park up, when driving engine seems slightly rough, slight loss of power, if you have trip computer on instantaneous mpg you will see it dip for 5-10 minutes)

Edited 4 April, 201610 yr by bluecar1

I think its clear that your commute is too short for a diesel. By the time the engine has got to a temperature where it will allow a regen, you have probably finished your journey.

 

I only have a relatively short commute of 12 miles, but half of that is motorway where most of the time I set the cruise to 70 in 6th unless i'm running late, I also do plenty of short journeys on my days off and I rarely interrupt a regen. Is your commute through slow speed traffic?

 

What I would find useful would be an obvious tell tale sign that the car is doing a regen, I sometimes never come to a complete stop so I can't tell if the idle is high, so I might get to work and I've clearly interrupted a regen, but if I knew it was trying to do one I would of cained it down the motorway and put fuel economy aside.

I got fed up of the regens on my last car (Mk4 Mondeo) I had a remap done and dpf delete, which including writing the regens out the software and blanking the EGR, I had no further issues and even though the remap was a performance one I gained 4/5 mpg, Total for remap, delete, and a Dyno after was £320

A 10min run won't be doing the DPF many favours.

 

I do drive some four hours each way, once a month though! But there are lots of little journeys in between... The light seems to come on like two days before Im going up north.. Kinda annoying 

Tbh, this being said, I may well just go ahead, get it MOT'd next month, get the cambelt in, and sell it, because I do miss driving my hybrid, so I may well get a 2008+ Prius, that's done just a little over 100K and with a FSH - the rational being that if it's FSH it should have had its 100K service. Not exactly had this Skoda for long either!