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Adamantia

2009 E61 530D unusual DPF problems

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Hi All

 

I'm not one that normally has issues diagnosing complex problems, but this one is beginning to really stump me. Apologies for the length below, but some of the details might be important.

 

2009 LCI E61 530D, manual gearbox owned since Jan 2018 and done 25k since then, now at 156k miles. Previous owner had the DPF gutted and mapped out a few months prior to selling due to issues. It also had a stage 1 remap done at the same time, and was sold with just shy of 12 months MOT.

 

Car drove great, but the cat had clearly been removed along with the particulate filter so it stank like a bus. Only smoked briefly at cold start, and on hard acceleration (especially after pootling along calmly for a while before hand).

 

After purchase I quickly found, with little surprise, that both thermostats were buggered and the car never got above 70C, plus had numerous glow plug faults. I replaced both thermostats, all glow plugs and controller. Car was then faultless and warms up and runs at 90C no problem.
I also discovered the swirl flaps were blanked, and whilst on the LCI M57 they shouldn't be an issue it didn't really bother me.

 

My commute is 35miles each way, of which 20-25 minutes is on fast dual carriageway. i.e. pretty good conditions for a diesel DPF

 

In December I wanted to reinstate the cat/DPF and map it to expect the DPF again. This was done both to make sure I didn't have any MOT issues with the new changes brought it (MOT end of Dec) and to fix the terrible bus smell. Since I've had previous success with aftermarket new DPFs, I bought and fitted one to replace the gutted BMW can. A local tuner took a stock ECU file for my ECU version, coded out the EGR but left the DPF behaviour, and gave a new stage 1 remap (old one was pretty poor, though it did drive ok).

 

After several problems making it gas-tight on the DPF/turbo flange, I found that I was getting excessive exhaust back-pressure and thus the car would constantly be trying to regen to clear the apparent soot load. I replaced the aftermarket DPF with a refurbished OEM one from Germany (i.e. a used DPF that's been cleaned out of soot and ash). Unfortunately whilst there were some improvements, I'm still getting the same behaviour.

As a cheap and simple form of troubleshooting, I've replaced both exhaust temperature sensors and the pressure sensor with used BMW items. No difference noted. There are no DME error codes, and the sensor readings seem sensible.

 

Even after an apparent regeneration, the back-pressure at idle when cold is ~12-16mbar. Once it warms up to ~200-250C the pressure increases to ~24mbar. The ISTA/DIS tests show the back-pressures are:
idle - 22mbar (limit 35)
2000RPM - 46 (limit 75)
3000RPM - 92mbar (limit 130)
cutoff/4kRPM - 157 mbar (limit 200)

 

I've noticed the car was call for a regeneration once the soot mass rises above ~42g. However even after a regeneration (which might drop the soot down to ~28g over 45 minutes or so), it very quickly rises back up to around 39-40g. It then increases slowly until it starts another regeneration cycle. It seems to estimate soot mass both from the pressure sensor but also an estimated curve based on how long it is regenerating and what temperature the DPF is at. Once it finishes a regen, the soot estimate quickly rises back up using the data from the pressure sensor alone.

 

When it does a regeneration, the temperatures behaviour a bit oddly. It will go 'active', exhaust temp rises quickly to 520-600C. The DPF exhaust temp lags behind a bit (since it has the cat between it and the first exhaust temp sensor). Once the DPF temp reaches 520+, the regen 'active' flag goes off. The exhaust temp quickly drops, and the DPF temp lags behind a bit. Once the DPF temp drops down below ~420C (after 20-30 seconds), the regen goes active again, and the cycle repeats. The system yo-yos like this the entire time, until I end the journey. If I 'force' a regen and drive at 70 continuously, it will do this behaviour for about 30-40 minutes, then actually 'complete' the regen and resets the miles-since-successful-regen counter to 0. I think this is just a time-out. I've also noticed that the measured back-pressure drops by ~1/3 when regeneration is active - I think this is the throttle plate (just before the EGR) partially closing to increase exhaust temps (I can also see the commanded EGR/throttle increases from 5% to ~30-50% at the same time). The EGR tube is disconnected and blocked.

 

From previous experience, others people's descriptions and a few graphs of other people troubleshooting the M57 DPF, I would expect when a regen starts the system will get the DPF temp all the way to 600C+ and it will stay up there until the end - i.e. not yo-yo between 400-520C.

 

I'm wondering if this is my problem (i.e. it doesn't really get and stay hot enough to fully burn off all the soot, but is enough to maintain a soot level around 40g).

 

Alternatively problems I could have, in order of likelihood:
- Both aftermarket and 'cleaned' OEM DPF actually have ~40mbar soot equivalent back pressure, and showing the same issue.
- New ECU map is wrong, either for measuring back pressure or DPF regeneration
- Faulty DME/wiring affecting the pressure sensor readings (i.e. back pressure is actually lower)
- DPF is clean/clear after regen, but rest of exhaust system has partial blockage
- Engine is producing so much soot, even during regen, that DPF is always partially blocked. I have seen some comments that blanked swirl flaps increases soot emissions, though only in town driving.

 

I can actually feel when the regen goes in and out of active, probably as I have a manual gearbox. Slight change in available torque for the same accelerator position. Apart from that, the only sign of a regen is if I come to a stop when temps are still high, the engine bay smells slightly 'hot' (creeps in through air vents). Exhaust tips have remained clean since I fitted the DPF (they were filthy before!).


Reported ash mass (which reset when installing the new DPFs and using ISTA to tell the ECU this) is increasing very slowly, around 0.1g per 100 miles. It also increases by a fixed amount of 0.22g each time I 'force' a regen. It's currently at a reported 0.51g. I'm not sure how the ECU calculates this value.

 

Attached are some graphcs I've made of logged data to show what is happening: 
Aftermarket DPF, attempting regeneration, long drive

OEM DPF attemped regeneration

OEM DPF, regeneration stopped by disconnecting throttle actuator

 

TL;DR
Is my DPF regenerating properly? If it is why do I have such high backpressure even after a successful reg?

 

Thoughts and advice much appreciated!

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Interesting post, this is a real minefield. I have a similar issue myself, I've replaced thermostats/glow plugs, cleared codes etc trying to get my DPF to 'behave' normally, but I'm still none the wiser. I managed to force a regen a couple of months ago but since then (2k miles) it hasn't done another. I also have blanked swirl flaps and have been told that could be the culprit, but I do hardly any town driving (my average speed is over 40mph.) So having spent 18 months since buying the car worrying about the DPF, I'm now just going to enjoy driving the car and worry about it when something actually goes wrong.

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3 hours ago, edd_jedi said:

having spent 18 months since buying the car worrying about the DPF, I'm now just going to enjoy driving the car and worry about it when something actually goes wrong.

^^. You seem to have gone to a great deal of trouble trying to largely return the car to its original spec and to eliminate problems, so all credit to you for that. When we bought our E60 nearly 4 years back I spent ages worrying about the DPF (that's when I wasn't worrying about catastrophic failure of the autobox).

Diagnostics via Carly gave me reams of DPF data but as I didn't know whether many of the readings were within acceptable limits I wasn't sure if the news was good or bad. Apart from thermostats being stuffed that is. Since replacing them I check the coolant temperature and how often it regens and just use it.

I'm not saying my approach is the right one, but I enjoy the car much more now I'm not worrying about it all the time.  :)

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I am very interested to hear  what other people have experienced with the DPF. So many people remove it as soon as there is any problem, when often it's just a symptom of an underlying problem. This is doubly annoying when the LCI DPFs are meant to have much longer service lives.

 

Part of my in depth look at this is having spent so much time and money (and bruises, the LCI DPFs are really awkward to get in and out) it isn't behaving properly.

 

One of the problems with the constant regens is my average MPG has dropped from 43 to 36, which when I'm doing 20-25k a year starts to become noticeable!

 

 

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2 hours ago, Adamantia said:

I am very interested to hear  what other people have experienced with the DPF. So many people remove it as soon as there is any problem, when often it's just a symptom of an underlying problem.

 

Nail on the head. People think they are solving the problem by removing it, but the DPF itself doesn't fail, they are still driving around running too cool, no working glow plugs etc.

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So, is the EGR still disabled?

Running at higher revs, it won't be doing much, but at idle the EGR will be recycling up to 50% of the exhaust gasses back into the intake. I know this sounds like a bad thing, but the idea here is to reduce the emissions that are coming out of the exhaust, which it achieves by sending unburnt fuel (inefficient combustion at idle, not helped by the lack of swirl flaps) back through the engine again.

 

On your car, all of this stuff goes straight through to the DPF, which is just doing it's job and collecting soot etc. The rate at which this stuff accumulates is far higher without EGR and swirl flaps, which might explain why your car feels the need to clear out the DPF so often. As you said, on an LCI the swirl flaps shouldn't present a problem, so I'd put those and the EGR back in the system and re-evaluate.

 

 

Steve

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While not agreeing or disagreeing with other comments, looking at your graphs, the regen status "yo-yos" from on to off every 20 seconds exactly. This can't be right. It's supposed to come on and stay on for 10-15 mins until complete. I would be looking at the software (mapping) side of things as the root of that particular symptom. 

 

Keliuss

Edited by keliuss

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You will need to put the car back to stock to really know, having had similar issues myself with frequent regens I have just fitted a brand new genuine inlet manifold to put the flaps back, the cars spend 90% of the time under 2k revs when the flaps are working to reduce emissions.

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Thanks for all the comments.

 

I'm having it put back to stock later in the week. The mapper confirmed the EGR has been disabled in software.

 

I've done about 150 miles with the throttle plate disconnected - this seems to stop the ECU from attempting to regenerate. Interestingly the soot mass increased to about 54g (from ~45) after about 10 minutes; It then stabilised and has slowly increased over the miles to 64g. I think this shows the 'real' affect of soot, so hopefully if the stock map fixes the regeneration behaviour, I can get a full regen in to find what the actual clean back-pressure is.

 

I think I will bite the bullet and put flaps back in the inlet manifold. I've seen the re-manufactured inlets from germany for 190euros. Is this worth it vs buying a good condition used item (and new gaskets) for £70?

 

28 minutes ago, GoNz0 said:

You will need to put the car back to stock to really know, having had similar issues myself with frequent regens I have just fitted a brand new genuine inlet manifold to put the flaps back, the cars spend 90% of the time under 2k revs when the flaps are working to reduce emissions.

 

That's interesting - have you found if this helps reduces how often it regens?

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I decided against a refurbished as they have cheap seals that leak, by the time you price up BMW seals the manifold doesn't seem that bad for a genuine new item

As for the regens it will be a while before I know, after it does one I will be monitoring it to see how long it takes.

I also will be picking up a used DPF with lower miles to clean out as a spare in the next week in case mine is past it.

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@GoNz0, a friend of a friend went into business recently specifically cleaning DPF's for the motor trade. I haven't seen it but his business is built around a small van sized piece of equipment imported from Italy at a price of approx. €50k. I think I read you cleaned yours with a power washer and chemicals (might have been someone else though). Anyway, my point is if you buy a backup maybe consider having it cleaned professionally as I can't imagine anything you could DIY would compare to whatever it is the Italian equipment does.

 

Keliuss

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Do you have his details?

 

Yeah chemicals and jet wash, an overnight soak and I did remove a lot of compressed ash. I have no one near me with proper equipment just the cowboys who inject a cheap can of cleaner and force a regen. 

I was considering attaching the DPF to a length of drain pipe and forcing water through with my drain rod kit as I got most ash out by physically filling the DPF with water and blowing it through with my lungs :lol:

 

Glad I had the gates shut, the neighbours would have been pissing themselves. 

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8 minutes ago, GoNz0 said:

Do you have his details?

 

 

Well it's in Dublin so I'm pretty sure you'll find someone nearer. AFAIK he just deals in DPFs already removed from cars, that are sent in from garages. The process was explained to me (albeit 2nd hand) a couple of years ago and I was driving a petrol E39 and a pre-DPF era diesel E46 at the time, so was only paying so much attention. TBH, it did sound a bit more involved than jet washers, drain pipes and a huff & a puff on the end of it :) 

 

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29 minutes ago, keliuss said:

 

Well it's in Dublin so I'm pretty sure you'll find someone nearer. AFAIK he just deals in DPFs already removed from cars, that are sent in from garages. The process was explained to me (albeit 2nd hand) a couple of years ago and I was driving a petrol E39 and a pre-DPF era diesel E46 at the time, so was only paying so much attention. TBH, it did sound a bit more involved than jet washers, drain pipes and a huff & a puff on the end of it :) 

 

I have been trying to find a hydro cleaning place near me but no luck :(

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