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      03-04-2010, 05:50 AM   #1
milesr3
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Too frequent DPF regenerations?

Folks,

My car seems to be doing lots of big DPF regeneration cycles as the moment (although it could also be the same incomplete one) and I wondered if anyone had any knowledge on this to share.

About 3 weeks ago I was driving along a dual-carriageway at a steady 50mph on the cruise control, when the car did a big lurch from the throttle feeling like it suddenly closed and opened again to re-establish the cruise speed. I clicked the cruise off and noticed than it needed around 1/2 throttle to maintain this speed and felt very sluggish and lacking power. At first I thought it was a turbo or actuator problem and it felt much more aggressive than any DPF regeneration I'd felt before. I had to stop the car after about 15 mins/10 miles and when I got out I could smell the exhaust and the tips were very hot. When I got back in I expected the DPF regen to re-start, but it didn't and it drove normally.

The next weekend I did a 400 mile round-trip maintaining speeds of 90-100mph and the car was fine.

Last weekend driving slowly though a village the car starts another DPF regeneration and once again I have to stop before it can finish. It's not as aggressive this time but it was definitely doing a regen because the exhaust is burning hot again despite me only driving slowly and it was holding a lower gear. Get back in the car and it drives normally.

Did a 140 mile trip on Monday and another high speed run of 140 miles yesterday and towards the end the car started another DPF regen, but this time I kept driving until it completed.

My concerns are:

1) In the last 9 months / 6,000 miles I've never felt such a big DPF regen. It could be that this is the only one it's done, but I thought it did it more often than this? I had though I'd felt a DPF regen before, but they have been very subtle and these were definitely not subtle at all.

2) The higher than normal speed driving I've been doing recently is suddenly making the car do lots of quite aggressive DPF regens, which would imply something is wrong...

3) It's just one incomplete regen cycle that has taken three attempts to complete. But why did it wait 3 weeks and 600 miles to do this. I thought it would retry as soon as the right conditions were available, which they have been many times before yesterday?

Edit: The car is re-mapped (e-maps) and I only ever use V-Power diesel in it.
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      03-04-2010, 06:07 AM   #2
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Maybe there is logic in there to decide "oh crap, mr owner has stopped when i was trying this....maybe it was a bad time, ill wait a few hundred and then retry"


No?


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      03-04-2010, 06:55 AM   #3
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Doesn't sound right to me either. I've had the subtle regens, even interrupted, for a short while, continued on the next drive, once conditions were correct again.

Was you 'continued drive', when you thought it would restart, while the engine was still warm?

There have been cases I've read, where DPF issues have no clear reason.

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      03-04-2010, 07:59 AM   #4
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In both cases when I re-started my journey the engine was still warm. Warm enough for me to expect the regeneration to re-start.

When the first big regen started I seriously thought it was a turbo problem, which was why I wasn't too fussed about keeping going.

It's the magnitude and frequency of the regens that making me question if it's normal as I've never really noticed them before with lots of steady part-throttle driving.

I used to think that giving a car a good 'italian tune-up' used to be a good thing, but wonder with a diesel if it just soots the thing up. I have done a couple of balls-out runs in it recently, although it's virtually impossible to really thrash one of these things without risking a serious bollocking or ban.

It's driving really well again, but if it keeps happening I may have to resort to taking it to the dealer to be told the computer says there's nothing wrong with it.
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      03-04-2010, 08:24 AM   #5
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I think the regen cycle may be by-passed if you are trying an "Italian tune-up".

From what I have read the cycle usually occurs when your car is warm enough and at a pretty steady speed, no undue loads.

From my own experience, not too many stop-gos and at a relaxed pace.

Sure it is actually the regen cycle you are feeling ?

It is quite subtle (many posters have not noticed). Slight labouring, bit like switching Aircon on in a small car. Certainly more underbonnet heat and a slight burnt caramel odour.

How about having a look at your bottom intercooler hose ? There is a thread in this section about it. EDIt : http://www.e90post.com/forums/showthread.php?t=281232

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Last edited by Dave_3; 03-04-2010 at 08:35 AM.
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      03-04-2010, 08:53 AM   #6
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I've certainly noticed regen cycles in the past that felt the same magnitude as an aircon compressor clutch cutting in and out with a slightly blunt throttle response. Always on a steady cruise. One was so subtle that I didn't notice until getting out of the car and hearing the exhaust ticking from the heat and the accompanying caramel/rubber smell.

These last three and the first in particular have been much more noticeable. May well not be a DPF regen, but the temperature of the exhaust tips and smell tends to suggest they were as there is no way the tips of the exhaust would have gotten so hot from 15 minutes of tootling down a dual-carriageway from cold with the last 5-10 minutes at <50mph in a contraflow.

Will have a look under the bonnet, although mine is a 535d (but I just hang out here because you know what you're talking about)

Last edited by milesr3; 03-04-2010 at 11:22 AM.
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      03-04-2010, 10:26 AM   #7
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One of the problems we do have with DPFs, you can't normally get any sense of overfuelling, or abnormal smoke levels. Even the garages seem to be confused when cars have DPF issues, as it is harder to find the causes. It is as if the DPF can mask other faults.

Has the mpg fallen recently, without reason?

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      03-04-2010, 11:15 AM   #8
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Quote:
Originally Posted by HighlandPete View Post
Has the mpg fallen recently, without reason?
No, the current tank is on 34.8mpg which is pretty average and does tend to show that although I've been stretching its legs a little recently I've not been driving like a total loon.
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      03-04-2010, 12:38 PM   #9
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Ive done 5000 miles since November, and have never noticed anything like this happening.
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      03-04-2010, 01:01 PM   #10
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Thumbs down

I'm one of the few on here which can say they can witness regenerations. Any OBD reader will pick up DPF inlet temperatures, the one i have has user controlled alarm LED lights as well. Bloody difficult to miss these lights when temperatures go up, which is pretty exactly 600C if the ECU can control it given the driving conditions. And under off throttle/idle it does not generate 600C, it drops to 200C.
Also the car does not buck, bang, lock up gears or anything during regeneration. It simply adds a late fuel injection when it thinks it can do while the exhaust valves are already open.
I have never, ever, felt a thing while seeing the temperature go up from around 300C average to 600C (20+ times now), nor coming down immediately when you have to lift off because of traffic.
Call me nuts - when regeneration starts i adopt to a defensive driving style so I can keep minimal throttle during the 5-8 mls or so it takes at 70 mph, to allow a complete, uninterupted regeneration
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      03-04-2010, 02:08 PM   #11
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Sorry guys - thumbs down header was not intentional and don't seem to be able to edit it.

Quote:
Originally Posted by F104 View Post
I'm one of the few on here which can say they can witness regenerations. Any OBD reader will pick up DPF inlet temperatures, the one i have has user controlled alarm LED lights as well. Bloody difficult to miss these lights when temperatures go up, which is pretty exactly 600C if the ECU can control it given the driving conditions. And under off throttle/idle it does not generate 600C, it drops to 200C.
Also the car does not buck, bang, lock up gears or anything during regeneration. It simply adds a late fuel injection when it thinks it can do while the exhaust valves are already open.
I have never, ever, felt a thing while seeing the temperature go up from around 300C average to 600C (20+ times now), nor coming down immediately when you have to lift off because of traffic.
Call me nuts - when regeneration starts i adopt to a defensive driving style so I can keep minimal throttle during the 5-8 mls or so it takes at 70 mph, to allow a complete, uninterupted regeneration
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      03-04-2010, 04:58 PM   #12
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I suppose it depends on the circumstances. For example, if it starts on my 330d, then I have to drop speed for some reason it holds on to 5th gear, even when I get back up to 60mph, will do this for about 8 miles.

I was with one of BMW's area technical engineers and we got to talking of the PDF regens. His advice if you detect a regen, (the gear hold and/or the harder edged combustion some of us feel) if possible "give the engine a bit of head", let it do its job easily.

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      03-05-2010, 03:44 AM   #13
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It would certainly make sense to ensure that the DPF has plenty of gasflow to regenerate. When I first got my car I took it back to the dealer complaining about the throttle response - at a steady cruise opening the throttle caused hesitation. They found that the car was requesting DPF regeneration but the conditions hadn't been met, despite me doing some reasonably long journeys. The technician took it out for a spirited drive and manually triggered the regeneration and all was well. He confirmed that you needed to drive it quite hard to assist a complete regeneration.

I think I've read somewhere, although I may have imagined it, that interrupting the regeneration cycle can somehow make it harder to regenerate next time around. I've certainly had two interrupted DPF regenerations in my car in the last month and possibly more beforehand that I haven't noticed. Perhaps this might explain the more aggressive regeneration I felt the first time.

I now wonder if enthusiastic driving will stall regeneration triggering. All the regenerations I can remember have happened when I've been driving very steadily and the last one I had on Wednesday happened when I'd backed off in the last 5 miles from home to let the car cool down a bit before switching it off.
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      03-05-2010, 08:47 AM   #14
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The other thing you may notice during a re-gen is a slight engine "throb" as the injectors activate "off stroke" to increase engine temperature. I always felt this through the seat as it felt like the car was misfiring.
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      04-12-2010, 05:50 AM   #15
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I had another big regen on weds last week that kicked in as soon as it had warmed up and lasted a good 20+ miles / 20 minutes with a significant drop in performance. They seem to be coming every few hundred miles now.

I called the dealer and they agreed that it didn't sound right and are going to look at it on Thursday...
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      04-24-2010, 03:17 AM   #16
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Just for the benefit of closing this thread, I eventually got to the root of the problems I'd been having with DPF regens.

The dealer diagnosed that I needed a new DDE (ECU) unit and some parts of the loom due to water ingress. I was a little sceptical, but they fitted and re-programmed a new DDE unit, some parts of the loom and cleaned some of the earths on Thursday.

The car is transformed!

It's a lot more responsive and smoother. It's immediately noticeable just blipping the throttle at idle where the revs now jump immediately with no lag at all. On the road the throttle is less immediate back on the standard map, but it is more responsive. I don't think it's much, if any slower on the standard map than it was on the remap, which goes to show how badly it was running despite still returning good fuel economy. Needless to say, I'm looking forward to getting the remap back on it again.

I wonder now if the frequency of DPF regens wasn't down to mis-fuelling or over-fuelling rather than mis-reading a sensor or mis-calculating when it needed a regen. It certainly feels a lot crisper and less lethargic now. I did a 320 mile trip on Weds, just before the new DDE was fitted and it drove terribly - doing another DPF regen and then 'misfiring' on a light throttle afterwards. With a DPF in the system there is just no way of seeing if it is over-fuelling.
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      04-28-2010, 05:06 AM   #17
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Quote:
Originally Posted by milesr3 View Post
Just for the benefit of closing this thread
I spoke too soon

The car lost power at low rpms for about 2 hours / 100 miles yesterday. I'm now beginning to think it's an intermittent turbo or actuator fault like the one I had when I first bought the car that was caused by the valve that bypasses the small turbo seizing.

I dropped it off at the dealers on the way past yesterday and await their new diagnosis...
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      04-28-2010, 07:09 AM   #18
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Whats your 535d's mileage and year?

I've been asking around for typical x35d issues so this sounds like one to add to any potencial list.

The only way I can tell when my car is in regen mode is that I will sit on the motorway at 80 and the mpg will be down to 30 when its usually at 40 (by my eye) this lasts for 10-20mins and then the mpg returns to normal.

I just leave it to do its thing.
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      04-28-2010, 07:39 AM   #19
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Quote:
Originally Posted by rsmallwo View Post
Whats your 535d's mileage and year?
It's a '55 plate 2006MY car. Mileage was 30K when the actuator first seized, it's now on 42K. Turbo and actuator assembly problems are common on these.

I've given up trying to guess what might be causing this. I've never noticed regens before as well, but it's now doing something that kills the throttle response every 300 miles or so which co-incidentally is the mode that the DPF is regenerated if the exhaust back pressure or temp sensors fail. The times I've stopped the car the exhaust is ferociously hot too. In between it drives fine and returns good economy (35mpg average). This would raise fault codes though and the dealer would have spotted these before swapping out the DDE. I still think it's DPF related, but something doesn't add up...

Last edited by milesr3; 04-28-2010 at 08:08 AM.
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      05-11-2010, 02:07 PM   #20
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Got my car back from my local dealer today.

Fortunately their senior tech agreed that it wasn't driving as it should and wasn't put off by a lack of fault codes (unlike the supplying dealer that I left it with the previous week). They've spent just over a week going over it with a fine-tooth comb and found:

1) It isn't a DPF issue. They forced a regen and the car drove as well as it did when not regenerating. The DPF back-pressure was zero and because they didn't believe the DPF could be this clean they took it off and looked inside and tested the sensor and confirmed this was working and didn't have a hole in it. Seems that lots of decent length journeys and V-power/Ultimate diesel can work wonders for your DPF then.

2) One of the turbo control valves was incorrectly adjusted and not seating correctly which was causing the exhaust gases to leak around the small turbo. This seems like the most obvious cause of the low rpm / low throttle hesitation. AIUI this was a very time consuming job to do with vacuum gauges - just like balancing a set of carbs!

3) The gearbox adaptation values were screwed, causing hesitant, harsh gearchanges. These have been reset and more importantly re-learnt by driving a specific pattern of acceleration and deceleration runs. This has made an enormous difference in the way that the engine and gearbox seem to be working together now rather than fighting each other. The gearbox is now changing down from 6th to 5th at 50mph which seems to keep the revs up above the point where the hesitation was most pronounced due to bogging down with no boost in too high a gear.

A big thanks to Adrian at Cooper BMW in Ipswich for some good old-fashioned fault finding and common sense!

A big thumbs down to the supplying dealer who couldn't find anything wrong with it because there were no fault codes and who supplied the car with a seized turbo control valve and then set it up wrong when they replaced it...

Last edited by milesr3; 05-11-2010 at 04:29 PM.
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      05-11-2010, 03:47 PM   #21
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glad you got it sorted, hopefully thats the end of the issue for you.
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      01-19-2011, 07:47 AM   #22
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Question Regeneration In Dde Requested

Hello everybody,

I post here because, it's the best place for talking about particle filter in the web :hyper:

i have a 325d from 03/2007 with 68 000km and this model of particle filter :



i have no message errors in DDE, no fault in my car, so diag is good.

-> but with DIS i have seen that the status in DDE, is always in "REGENERATION IN DDE REQUESTED"



So i decided to make a test with DIS, and the exhaust back pressure is good :

(see pictures below)

It's normal, because no warning message.

I always do highway at 110 - 150 km/h, 70km.

So engine hot, exhaust temperature above 240degrés etc ... but i have the impression that the regeneration did not take place.

(See pictures below)


So my question is :

How do you do for force the regeneration in DIS (where in the menu) ? it's in the menu after the SAV fonction where you can test the exhaust back pressure ?
T think, that if i force a regeneration, my DDE status become normal.

Thanks
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