Ever wondered what happens when you push the handbrake button whilst driving ?

[DSGboy]

I felt the ABS working for the first time in 45k the other day when I had to brake from around 30 to zilch, and I don't think the hazards came on, so they must activate at a higher speed.

(Car in front came to a complete halt for no apparent reason when an ambulance with blue lights flashing happened to be coming the other way - don't you just love 'em?)

Driving too close then man, why do it to yourself?

[Stuart W]

Stuart, there was a thread on here "DPF - does it clean itself in the city?" https://www.vwaudiforum.co.uk/forum//...ad.php?t=18991

Does yours, as a taxi, get a chance to clean itself? Have you any thoughts on this?
John

Well I try not to think about it to be honest, John

At least, I've never had a problem with this, and the warning light has never come on.

However, I know another taxi driver who has a Skoda Superb with the 2.0 140 bhp lump (ie the same one as mine), and he's had no end of problems with his DPF, and I think he's been towed to the garage once or twice, and the warning light has come on quite often.

The only difference I can think of is that he lives a few hundred yards from where he wants to get to, so I could well see him driving this distance then stopping the car for a good while, then doing a couple of short taxi runs in a couple of hours and thus the engine would never get up to full operating temp. (Mind you, he does do more long distance stuff than I do.)

On the other hand, I live about eight miles from where I want to go, so I usually do this before stopping the car, therefore it's always up to operating temperature (at least as far as the coolant temperature guage is concerned, which is usually up to the 90 degrees mark within about four miles or so - I don't know about the DPF, but I've read that the cat takes about fifteen miles straight driving to get up to temperature?).

During a normal shift the temperature will certainly drop a good bit between runs (which can easily be a couple of hours apart) but if I do a run then the engine will certainly get up to operating temperature during the run, which presumably will help on DPF-wise. Perhaps the problem is related to the car being driven regularly without getting up to temperature rather than urban driving per se?

I had a look at the manual earlier and it says the best way to avoid or sort the problem is to drive at around 2000 rpm in 4th or 5th, and my run home is generally at least ten miles at roughly this (it's mainly A roads), so if there's any build up then presumably this run will help get rid of it. Most days I won't be revving it much above 2,500 rpm anyway, but if the manual is correct then high revs won't sort the problem anyway.

The only other thing I can think about with the Superb driver is that he seems to have some sort of additive injected into his, and he says that Skoda have told him that this must be replenished at about 100k or so, and he'll have to pay to have his done.

The Passat manual has a section under the DPF bit headed "Without additive", but doesn't have a "With additive" section, thus presumably this means that that Passat doesn't have an additive but the Superb does? There's no mention of an additive in the service schedule either, but it does say that the DPF must be checked at around 100k or so.

Anyway, the Superb driver said that the dealer had been told by Skoda not to sell any more of the 140 bhps to taxi drivers and instead keep on selling them the 1.9 115/130 bhp engines. I'm not sure if Volkswagen are thinking likewise, but I don't think they do much business with the taxi trade (at least as regards cars) whereas Skoda shift huge numbers to taxi drivers.

Just a thought from the other thread however; I would definitely have a DPF, would I? From what's said in the thread the DPF is optional on the 140bhp engine? It's not a thing that I thought about or was brought to my attention when I bought the car.

[Stuart W]

Driving too close then man, why do it to yourself?

Now why did I know someone would suggest this

If I'd been too close I think it would have been an airbag rather than ABS job, but as it was I managed to stop with plenty of space to spare.

I'm not in the habit of tailgating, and indeed it's one of my pet hates, but if I did contribute to the near-incident then perhaps I was distracted by the emergency vehicles on the other side of the road (there were actually two, separated by a couple of cars) and thus when the car in front did start braking I was perhaps a bit slow to react.

However, if a car does what in effect is an emergency stop in front of you for no obvious reason then I suspect that most drivers following would have to brake pretty smartish as well, even assuming they're at a safe distance. Also, where the car in front braked was also a position where it would be expected to brake slightly anyway, so when it actually came to a complete halt it came as a bit of a surprise.

[DSGboy]

Now why did I know someone would suggest this

If I'd been too close I think it would have been an airbag rather than ABS job, but as it was I managed to stop with plenty of space to spare.

I'm not in the habit of tailgating, and indeed it's one of my pet hates...

However, if a car does what in effect is an emergency stop in front of you for no obvious reason then I suspect that most drivers following would have to brake pretty smartish as well, even assuming they're at a safe distance.

Of course it wasn't a major criticism at all, my tongue was firmly in my cheek, and fair play to you for driving safely enough to avoid any collision.

I have been quite fascinated recently reading up about safer driving, and one interesting fact I saw was that the 2 second rule is pretty much nonsense - it only represents the correct braking distance if you are travelling at 19 mph. Any faster and there will be insufficient space between your car and the car in front to stop in time. Normally we are ok because the car in front doesn't stop dead, but if it hits something heavier it just might!

[Quatrelle]

I have been quite fascinated recently reading up about safer driving, and one interesting fact I saw was that the 2 second rule is pretty much nonsense - it only represents the correct braking distance if you are travelling at 19 mph. Any faster and there will be insufficient space between your car and the car in front to stop in time.

2 seconds at 19mph is 17metres distance, 2 seconds at 70 mph is 62mtrs distance (approx.) from the vehicle in front.

The Highway Code says that the stopping distance at 20 mph is only 12 metres, at 70 mph it's 96 mtrs.

These, note, are stopping distances, so yes 2 seconds wouldn't be much good over about 23 mph.

However, the 2 second rule is designed to give you thinking distance, so (if your brakes are as good as the vehicle in front) it works ok - unless the vehicle in front stops dead, which it won't unless you follow it into a collision with a stationary, very large object or, unhappily, something perhaps crosses the centre reservation.

So, to be completely safe, 3 seconds might be a better bet at higher speeds, but it's not often the vehicle in front will stop dead.

I'm happy to use 2 seconds - the biggest variable is how quickly, or slowly, you count to 2 seconds

Either way, it leaves plenty of room for someone to pull-in in front of you, ruining your 2, or 3, seconds

[Quatrelle]

Stuart
Your account is interesting...made me read my manual on the DPF and as you say, the lower gears should do it. Interesting also that you can clean it yourself, so to speak. Mine had a couple of hours on the autoroute at 130+kph/2300 rpm on Friday, so it should now be spotless! Because of the hilly, winding roads round here, I'm often in 3rd or 4th - not much good for mpg though.

p.s. There's no mention of 'additive' in the French driver's handbook.
John

[Stuart W]

There's no mention of 'additive' in the French driver's handbook.
John

I had a word with the Skoda Superb driver last night, and I was wrong about him being towed to a garage - what he says happened once or twice is that the warning light has come on, the performance has suffered and he's had to go to the dealer to get it sorted because it won't clear.

He also says that the warning light has been on a lot of the time without any adverse effects, but he did get the additive replenished at about 70k (ie 100,000 km) and the problem seems to have disappeared; he's done about 10k since then without problem. (Cost him around £200 for the new additive)

As for the Passat, it may be that it's just short runs where the exhaust system doesn't get warmed up properly that's the problem (ie old lady driving a mile for the shopping twice a week, kind of thing) so for the average owner it shouldn't be a problem.

[Stuart W]

So, to be completely safe, 3 seconds might be a better bet at higher speeds, but it's not often the vehicle in front will stop dead.

I probably leave three or four seconds on a quiet, fast road but of course if it's busy then people will tend to view this as an overtaking opportunity, even though all they achieve is one place and maybe cause a bit of grief while overtaking, so maybe a smaller gap is preferable in those circumstances.

Also, if you leave too big a gap then many people seem to see that as an excuse to tailgate you, even though they have no apparent desire to overtake.

Of course, it's easy to get a bit pedantic about all this, and if even the vast majority of people observed something approximating to the two second rule then that would be a major achievement

[Quatrelle]

He also says that the warning light has been on a lot of the time without any adverse effects, but he did get the additive replenished at about 70k (ie 100,000 km) and the problem seems to have disappeared; he's done about 10k since then without problem. (Cost him around £200 for the new additive).

Silly question perhaps, but what is the 'additive' that it costs £200? The only additives I know are things that you add to fuel or oil

[Stuart W]

Silly question perhaps, but what is the 'additive' that it costs £200? The only additives I know are things that you add to fuel or oil

Don't know, but there's a Skoda PDF (or should that be DPF?!?) document which explains the DPF process, which is the top link on the following Google page, and it mentions the 2.0 TDI 103kW (ie 140 bhp) engine. However, it doesn't really expain much about the additive:

http://www.google.com/search?hl=en&s...e+filter+skoda

So hopefully the Passat is the "without additive" option and instead benefits from the "passive regeneration" and "active regeneration"??