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Thinking about a Diesel? You Need to know about DPFs
mickeypops
Posts: 596 Forumite
DPF = Diesel Particulate Filter
I bought my Zafira brand new 3.5 years ago. I bought a diesel even though my mileage is fairly modest - 8K p.a. - because I "like" diesel engines and because I believe they're more "green" as they use less fuel. I love my car and it's behaved impeccably. I just wish the showroom had explained to me about the DPF and its need to "regenerate" every 500 - 1000 miles or so.
The DPF catches nasty particles that we don't want in the atmosphere. Great. It will clog up though, and the car break down, if the filter isn't cleaned every so often. The car does this automatically by going through a regeneration process every so often. When the engine computer decides it's time, it changes the engine settings so that the engine runs more richly to get hotter. It switches on the heated rear window and door mirror heaters to increase the load on the engine. This process lasts about 15 minutes, during which time the Trip Computer informs me that my fuel consumption has about doubled.
Now, most of my driving is relatively short runs around a city. The regeneration process won't start until the car is warmed up, say 10 minutes. The process then runs for exactly 15 minutes. I don't do many runs of 25 minutes or more, so I've learned that I have to just drive around aimlessly until it's finshed its regeneration.
The alternative is very, very irritating. When the car was new, and I knew nothing about this, I was aware that the car engine was behaving strangely and of course I was worried. I arrived at home and switched off. The next morning I was relieved upon start up that all seemed normal, but as soon as the car warmed up it started to regen again, because it knew the prior process was interrupted. And it will do this again and again until the process gets completed normally.
In the end I took it to the dealer and the mechanic explained what was happening. He also explained that diesels aren't recommended for people who have a driving pattern like mine, for this very reason.
So, I buy a car for its economy and low usage of resources, only to find that I have to drive around at least once a month just wasting fuel! How green is that, not?
Also, you'd think they'd have the sense to give you a meter or something indicating the imminent need to regenerate, so that you could manually set it off at a suitable time when you know you're going to be driving for a decent stretch. Last week, for example, I parked up one night having driven 150 miles. The next flippin' morning, it started to regenerate when I was giving the other half a lift, a 10 minute journey. What a waste - I had to drive around uselessly for 15 another minutes.
Anyway, the point of this post is to remind people thinking about a diesel to find out about the particular model's method of dealing with particulates in the DPF. They don't all do the same as my Vauxhall, but quite a lot do.
I bought my Zafira brand new 3.5 years ago. I bought a diesel even though my mileage is fairly modest - 8K p.a. - because I "like" diesel engines and because I believe they're more "green" as they use less fuel. I love my car and it's behaved impeccably. I just wish the showroom had explained to me about the DPF and its need to "regenerate" every 500 - 1000 miles or so.
The DPF catches nasty particles that we don't want in the atmosphere. Great. It will clog up though, and the car break down, if the filter isn't cleaned every so often. The car does this automatically by going through a regeneration process every so often. When the engine computer decides it's time, it changes the engine settings so that the engine runs more richly to get hotter. It switches on the heated rear window and door mirror heaters to increase the load on the engine. This process lasts about 15 minutes, during which time the Trip Computer informs me that my fuel consumption has about doubled.
Now, most of my driving is relatively short runs around a city. The regeneration process won't start until the car is warmed up, say 10 minutes. The process then runs for exactly 15 minutes. I don't do many runs of 25 minutes or more, so I've learned that I have to just drive around aimlessly until it's finshed its regeneration.
The alternative is very, very irritating. When the car was new, and I knew nothing about this, I was aware that the car engine was behaving strangely and of course I was worried. I arrived at home and switched off. The next morning I was relieved upon start up that all seemed normal, but as soon as the car warmed up it started to regen again, because it knew the prior process was interrupted. And it will do this again and again until the process gets completed normally.
In the end I took it to the dealer and the mechanic explained what was happening. He also explained that diesels aren't recommended for people who have a driving pattern like mine, for this very reason.
So, I buy a car for its economy and low usage of resources, only to find that I have to drive around at least once a month just wasting fuel! How green is that, not?
Also, you'd think they'd have the sense to give you a meter or something indicating the imminent need to regenerate, so that you could manually set it off at a suitable time when you know you're going to be driving for a decent stretch. Last week, for example, I parked up one night having driven 150 miles. The next flippin' morning, it started to regenerate when I was giving the other half a lift, a 10 minute journey. What a waste - I had to drive around uselessly for 15 another minutes.
Anyway, the point of this post is to remind people thinking about a diesel to find out about the particular model's method of dealing with particulates in the DPF. They don't all do the same as my Vauxhall, but quite a lot do.
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Comments
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mickeypops wrote: »DPF = Diesel Particulate Filter
I bought my Zafira brand new 3.5 years ago. I bought a diesel even though my mileage is fairly modest - 8K p.a. - because I "like" diesel engines and because I beleive they're more "green" as they use less fuel. I love my car and it's behaved impeccably. I just wish the showroom had explained to me about the DPF and its need to "regenerate" every 500 - 1000 miles or so.
The DPF catches nasty particles that we don't want in the atmosphere. Great. It will clog up though, and the car break down, if the filter isn't cleaned every so often. The car does this automatically by going through a regeneration process every so often. When the engine computer decides it's time, it changes the engine setings so that the engine runs more rich to get hotter. It switches on the heated rear window and door mirror heaters to increase the load on the engine. This process lasts about 15 minutes, during which time the Trip Computer informs me that ny fuel consumption has about doubled.
Now, most of my driving is relatively short runs around a city. The regeneration process won't start until the car is warmed up, say 10 minutes. The process then runs for exactly 15 minutes. I don't do many runs of 25 minutes or more, so I've learned that I have to just drive around aimlessly until it's finshed its regeneration.
The alternative is very, very irritating. When the car was new, and I knew nothing about this, I was aware that the car engine was behaving strangely and of course I was worried. I arrived at home and switched off. The next morning I was relieved upon start up that all seemed normal, but as soon as the car warmed up it started to regen again, because it knew the prior process was interrupted. And it will do this again and again until the process gets completed normally.
In the end I took it to the dealer and the mechanic explained what was happening. He also explained that diesels aren't recommended for people who have a driving pattern like mine, for this very reason.
So, I buy a car for its economy and low usage of resources, only to find that I have to drive around at least once a month just wasting fuel! How green is that, not?
Also, you'd think they'd have the sense to give you a meter or something indicating the imminent need to regenerate, so that you could manually set it off at a suitable time when you know you're going to be driving for a decent stretch. Last week, for example, I parked up one night having driven 150 miles. The next flippin' morning, it started to regenerate when I was giving the other half a lift, a 10 minute journey. What a waste - I had to drive aroud uselessly for 15 another minutes.
Anyway, the point of this post is to remind people thinking about a diesel to find out about the particular model's method of dealing with particulates in the DPF. They don't all do the same as my Vauxhall, but quite a lot do.
How can this 15 minute process every 4 to 6 weeks have such a significant effect on your overall average fuel consumption?"You were only supposed to blow the bl**dy doors off!!"0 -
I think the point should be, if you're thinking about getting a diesel just to potter around to the shops and back, think again.0
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I guess in the scheme of things it's not a material cost, it's just wasteful - and that goes against the main reason for me buying a diesel in the first place.
Also, the engine behaves differently during the regen process, for example it "hunts" at tickover, there are strange ticking and clicking noises. I find it unpleasant.0 -
I think the point should be, if you're thinking about getting a diesel just to potter around to the shops and back, think again.
Well, I do a bit more than that, but your point is well made.
The main point of my post though is that I suspect a lot of potential car buyers will not be aware of modern diesel engine's DPF and the need to regenerate, or cleanse by some method, and they'd be well advised to find out.0 -
mickeypops wrote: »Also, you'd think they'd have the sense to give you a meter or something indicating the imminent need to regenerate, so that you could manually set it off at a suitable time when you know you're going to be driving for a decent stretch. Last week, for example, I parked up one night having driven 150 miles. The next flippin' morning, it started to regenerate when I was giving the other half a lift, a 10 minute journey. What a waste - I had to drive around uselessly for 15 another minutes.
Largely sound advice- diesels have never really been recommended for short City journeys and certainly that is very much the case now.
The above quote doesn't sound right to me. You should have two types of regeneration, active and passive. If you do a 'long' journey or really get everything nice and warm, (I do 15 miles at 50mph+ each way so things get warm touchwood!) the DPF should have the soot burned off with no problems. That is what should have happened on a 150mile run really.
Active regeneration is what you describe- where diesel fuel is sprayed about to help burn things off because things have been all clogged up after town journeys to get things hotter. Some times the 'eco' cars with long top gear ratios don't get enough heat to burn off the soot even though they are sitting at 55mph on the motorway.0 -
DPF's - yes they are a li'l secret, on some peoples vehicles.
Now, who's going to mention DMF's!!!
They a BIG li'l surprise!!
VB0 -
#flyingscotno1 wrote: »Largely sound advice- diesels have never really been recommended for short City journeys and certainly that is very much the case now.
The above quote doesn't sound right to me. You should have two types of regeneration, active and passive. If you do a 'long' journey or really get everything nice and warm, (I do 15 miles at 50mph+ each way so things get warm touchwood!) the DPF should have the soot burned off with no problems. That is what should have happened on a 150mile run really.
Active regeneration is what you describe- where diesel fuel is sprayed about to help burn things off because things have been all clogged up after town journeys to get things hotter. Some times the 'eco' cars with long top gear ratios don't get enough heat to burn off the soot even though they are sitting at 55mph on the motorway.
Thanks for the info, FS1. I'll certainly bear it in mind. The Zafira's 6th gear has a ratio in excess of 30mph per 1000 revs, so maybe it never really gets hot enough to do "passive" regen as you describe - plus, I can now go four or five weeks without a decent journey since my job spec changed last year.
Typical car manufacturer though. The handbook tells you nothing. The dealer told me nothing when I bought it. I've had diesels before but haven't come across this DPF and regeneration process before. It was a complete surprise. Honestly, I may have reconsidered and bought a petrol model.0 -
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dual mass fly wheel - part of the clutch assembly and a very common failure on lots of vehicles.0
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I have to agree that dealers/salespersons should make potential buyers aware of DPFs and the use the vehicles will be getting.
But by the same token potential owners should be doing some research themselves on the vehicles of their choice.
Although a DPF is fitted to all new cars now and should be common knowledge, it wasn`t the case when I bought my DPF equipped 2.7d Jaguar nearly 5 yrs ago because they were still a relatively rare occurence which even the dealers/sales were not properly informed about.0
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