CM93

What exactly triggers an active DPF regeneration?

Recommended Posts

Hello,

Can anyone tell me what exactly triggers an active dpf regeneration to occur? (2008 Ford Focus 1.6 TDCI) 

I've noticed (using forscan) that the dpf is regenerating approx every 100 miles. This seems very excessive especially considering the differential dpf pressure is well within the acceptable range when these regens are kicking off. Are regens triggered based on mileage? If so is there anything I can do to increase the mileage interval between regens?

I've searched online and haven't been able to find an answer yet.

Thanks :) 

Share this post


Link to post
Share on other sites
 

1 hour ago, CM93 said:

Can anyone tell me what exactly triggers an active dpf regeneration to occur?

No!wacko.png

As far as I can tell, the exact process is a bit of a mystery,  possibly known only to a few programmers working at Ford years ago. DP plays a big role, but past history seems to be taken into account.

Forscan should have PIDs for km from regen, & km to Ash Full, or similar, which can be monitored to get a clue.

There is also much debate about reasonable DPs. I have heard figures from 1kPa (at low revs & load) to 30kPa (must be max rpm & load, but still sounds much too high to me) touted about. The rpm, turbo boost & exhaust temp have a big impact on the dp, you need to set a baseline dp at a known rpm & speed/engine load, to be able to compare regen cycles.

Is the exhaust temp getting up towards 600C during a regen? If not, the soot will not burn.

If the DP does not drop after a regen, either the DPF is ashed up (that won't burn off), or not getting hot enough, or even the EOLYS (if it uses that) may have run out. The EOLYS "level" indication seems to just be a guess based on use, could be confused by not being filled properly, or a counter reset without a re-fill.

The sensors (Exhaust temp & DP), and the DP hoses can cause problems. Check the hoses. The DP sensor can be tested with an improvised U tube manometer, if you can get to it, and if you suspect it.

Maybe someone will contradict me, and come up with an exact trigger mechanism, but if so, they have been keeping pretty quiet about it so far!

Peter.

 

 

Share this post


Link to post
Share on other sites

Mine does several regens a week, sometimes maybe only twice a week, sometimes 3 or 4. My differential pressure is so low that I think the garage may have gutted it but not mapped it out.

I can't fathom it out as to how when and why. What I do know is after fuelling up it will do a regen within around 30-60 miles on average sometimes within just a few miles.

If a regen cycle has started but not completed then further attempts will be started, usually at the most inconvenient times after a couple of failed attempts it seems to forget it for a little while.

That is about all I can say other than lots of shourt journeys it will regen far more often, longer journeys and it should regen less often.

Share this post


Link to post
Share on other sites

Even Ford technical couldn't tell me when I asked!  But that was almost 2 years ago now tbf. 

Every 100 miles is far too often unless it's all slow town driving and short journeys?  Is the regen being interrupted or does it complete as it should?  There is no way to alter it unfortunately, I would suggest you have another fault such as a stuck EGR or leaking boost hose if it's carrying out a full regen that often under normal driving.

 

Share this post


Link to post
Share on other sites

Well as clockwork, filled up yesterday, done 30-40 miles since and today it did a regen but failed as I didn't have time to drive long enough once it started.

 

Share this post


Link to post
Share on other sites

Thanks for all the replies - really good info.

Quote

Forscan should have PIDs for km from regen, & km to Ash Full, or similar, which can be monitored to get a clue.

I've been using these for the last few weeks. A new regen starts every time the 'km from last regen' counter hits around 180km. 

To PID for 'km to ash full' does seem to be a bit off. It's counting up as opposed to down (every time I drive 1km the distance to ash full goes up 1 km). I don't think this should be causing any problems though.

Quote

There is also much debate about reasonable DPs. I have heard figures from 1kPa (at low revs & load) to 30kPa

I've noticed lots of figures mentioned too but I've had regens kick off without ever going over 4-5kPa and it only reaches that when accelerating hard.

Quote

Is the exhaust temp getting up towards 600C during a regen?

The regens seem to be working perfectly. As soon as I see a regen kicking off I take the car to the motorway for a quick blast. If it happens at an inconvenient time I'll let the first regen fail but I'll take it straight to the motorway on the next journey (so never more than one failed attempt each time). Once on the motorway the exhaust temp climbs to around 650C and then the temperature falls again and the 'km from last regen' counter resets to zero. I take this to mean that the regen was successfully and revert to normal driving (5th gear). The whole process normally takes 15mins or less. After the regen the DP does drop a little but it was never that high to begin with.

Quote

Every 100 miles is far too often unless it's all slow town driving and short journeys?

I do a mixture of journeys, including motorway + long runs. I do some town driving but I am rarely stuck in traffic or low speeds for long. The regens never seem to kick off on the motorway unless I've reached the 180km since the last regen. I've tried blasting it hard after 130km but it doesn't appear to have any interest in doing a regen then. 

Quote

 I would suggest you have another fault such as a stuck EGR or leaking boost hose if it's carrying out a full regen that often under normal driving.

The car is driving perfectly apart from the annoying regens. Would I notice symptoms if this was the case?

Quote

What I do know is after fuelling up it will do a regen within around 30-60 miles

Great information, I didn't know that.

 

Also just to note I had my DPF completely cleaned out 6 months ago at around 100,000 miles after getting the engine malfunction light. So my ash levels should be fairly low and the the ELOYs fluid was also filled at the time so no problems there either. I got it done by a specialist so I'm assuming they did a pretty good job. 

Thanks for all the feedback this has been much more productive than all my googling lately :smile:

Share this post


Link to post
Share on other sites

This may be a silly question, I have a Mk3, so how do I know when a regen has started or finished.

Share this post


Link to post
Share on other sites
30 minutes ago, SuttonRider said:

how do I know when a regen has started or finished.

Use Forscan. It can monitor exhaust temperature (among many other things), and shows "km from Regen", which drops to zero after a regen.

It will also help diagnose possible dpf, and Many other, problems.

Ideally use a Windows (or Linux)  laptop or notepad with USB. There are variants for iPhone & Android.

It is a powerful Ford specific system. Cost £15.00 for the interface.

You will find a lot about ELM327 & Forscan on this site, which together provide a very comprehensive diagnosis & maintenance tool.

James (jeebowhite) has done a nice guide: http://www.fordownersclub.com/forums/applications/core/interface/file/attachment.php?id=21196

For an ELM327 adapter, see
http://www.spanglefish.com/TunnelratElectronics/index.asp?pageid=516992


you will also need a program called Forscan, its free and you can get it from

http://forscan.org/download.html

Peter.

Share this post


Link to post
Share on other sites
52 minutes ago, CM93 said:

If you prefer a wireless adaptor I bought the one from the link below and it works well so far:

I see it claims to be ELM237 compatible.

Is that the adapter you have been using with Forscan? And it works ok (adequate bit rate)?

The reason I ask, is that there are a lot of bad wireless ELMs on offer, and a known good make would be nice to be able to recommend to others.

Unfortunately it does not have the MS-CAN modification, that I can see. It may be possible to add this if the case can be opened, and there is space to add the switch. Have you looked at this option at all?

(MS-CAN is needed to access the BCM/GEM, Door modules and other body modules. It uses another pair of pins on the DLC.)

Peter.

Share this post


Link to post
Share on other sites

Quote

Is that the adapter you have been using with Forscan? And it works ok (adequate bit rate)?

Yes, I've used it with both Forscan and Forscan Lite (Android mobile version). It works perfectly for me and the Forscan application says that the connection is good with no errors - "Min.delay: 15ms (Good)".

I haven't looked at the MS-CAN modification but I doubt it would be suitable for that.

Share this post


Link to post
Share on other sites

Back to the original topic of the thread, I have a theory as to what might be causing the frequent DPF active regens.

Currently the value for "Distance to Ash Full" 1850km (and going up). This is clearly wrong since all the ash was recently removed but I didn't take much notice as I didn't think this value was that important.

However, if the car believes the DPF is almost full with ash then it would also assume there is not much room/space for soot accumulation. As a result the car might be triggering regens more frequently as the distance to ash full value decreases. I've read that the preset value from new is 99,999 miles.

I will contact the garage who cleaned the DPF tomorrow and see what their thoughts are.

Maybe I'm trying too hard to apply logic to DPF's!!

Share this post


Link to post
Share on other sites
3 hours ago, CM93 said:

I've read that the preset value from new is 99,999 miles.

I will contact the garage who cleaned the DPF

Was the DPF system reset after the DPF was cleaned?

When fitting a new DPF, or if the DPF has been successfully cleaned, it needs a reset, to tell it to re-initialise all its values.

Forscan can (so I have heard) do this. The value should jump up to 99,999.

On the 1st regen after a reset, the values like km to Ashfull can jump about dramatically, so it is no use doing this on a clogged DPF, but if the cleaning was successful, as the low DP figures suggest, then it should work.

See:
http://forscan.org/forum/viewtopic.php?f=6&t=247

It is a long & complex post, the writer tried reset on a clogged DPF, then cleaned it, and a 2nd reset seemed to work.

Any help?

Peter.

Share this post


Link to post
Share on other sites

You can reset the learnt values for the DPF this should only be done when the filter has been renewed, but even when reset the counter will take some time but will re learn the figures again after a period of time, how exactly it does this I do not know, most likely an algorithm that takes data from various sensors to adjust the value according to how the car is used, for example short journeys and low temps or long journeys and higher temps. 

I reset mine as I had nothing to lose and it soon got back to a figure similar to what it was before, now I just ignore the figures it says as it still works and I suspect mine has been gutted but not remapped.

Share this post


Link to post
Share on other sites
On 15/07/2016 at 7:11 PM, CM93 said:

I will contact the garage who cleaned the DPF tomorrow and see what their thoughts are.

Any news / progress on the DPF reset? Would be very useful to know if it worked.

Peter.

Share this post


Link to post
Share on other sites

Last week I had another regen after an interval of only 160km so I decided that I had to try something.

I didn't call the garage but I used Forscan to reset the DPF learned values. This reset the values for DIST_REGEN to 0km and DIS_ASHFULL to 100,000km (not miles like I thought).

I've only had one regen since then at an interval of 214km which is definitely an improvement. Hopefully this figure will increase a little further over time as the learned values gather more data.

The DIS_ASHFULL value has been very consistent since I reset it - no sudden changes like others have experienced. It's simply counting down by 1 every time I drive a km (no longer counting up like it was before the reset).

 

Share this post


Link to post
Share on other sites
On 20/07/2016 at 7:21 PM, CM93 said:

I've only had one regen since then at an interval of 214km which is definitely an improvement. Hopefully this figure will increase a little further over time as the learned values gather more data.

Any news? We would love to hear, good or bad, but preferably goodbiggrin.png

Peter.

Share this post


Link to post
Share on other sites

It's been a few months now so I'll give an update...

The increased distance between regens didn't last long and it's now back to doing a regen every 150 - 160km.

I've given up on bringing it to the motorway every time it needs a regen, instead I just leave it complete in normal driving. Sometimes the temp reaches 590+ other times it doesn't but I'm not too bothered because the differential pressure is still consistently low which leads me to believe the filter isn't clogging.

If I do see the differential pressure rise I will take it for a blast on the motorway but apart from that I'm not worrying about it.

Hopefully an oil change every 10,000 miles will be enough to counter the effects of so many regens.

Share this post


Link to post
Share on other sites
13 minutes ago, CM93 said:

differential pressure is still consistently low which leads me to believe the filter isn't clogging.

And is the DIS_ASHFUL (or whatever it is) figure still going down at the 1km per km rate, with no big jumps?

If so, that would seem to confirm that the ECU is happy with the DPF. I suspect a cleaned DPF is never going to be as low in pressure drop as a new one, and that could be the reason for the rather frequent regens.

13 minutes ago, CM93 said:

an oil change every 10,000 miles will be enough

A lot of 1.6TDCI owners on this site recommend shorter oil change intervals. 6k seems to be the preferred value. This engine can be prone to carbon build up, and it may not just be the DPF system that is the cause.

Really great to get this feedback, so many threads just end inconclusively. Many thanks,

Peter.

Share this post


Link to post
Share on other sites

Reading this topic with interest as my former car which I've passed on to my son is a  Focus 2.0 TDCI on 05 plate. When the car decides it needs to regenerate it starts to cough and splutter so to speak and then a puff of smoke out the back and we are good to go again, is this generally the norm or should it be slightly smoother for a regen. 

Share this post


Link to post
Share on other sites

Your car has a DPF with eloys fluid. When was this last topped up?

Share this post


Link to post
Share on other sites

Ive recently got a 1.6 focus 57 reg , i got a warning about dpf , ive had it on laptop with forscan and the miles to ashfull is 0 . I was driving down road with live data and noticed its doing a trying a regen it gets upto 600c for around 5-10 mins it then goes to 0 miles from last regen trial and after around 35-45 tries the regen again . Is this telling me the dpf is knackered first car with a dpf . Many thanks

Share this post


Link to post
Share on other sites
5 hours ago, davidoneman said:

i got a warning about dpf , ive had it on laptop with forscan and the miles to ashfull is 0 .

It certainly thinks the DPF is clogged.

First step is to check the hoses from the DPF to the DP sensor. These can fail, and give false readings. Next, if possible, check the Eolys level. Bu most accounts, there is no level sensor on these, it relies on counting doses. It it was under-filled at some time, it could go empty without any error message. The tank is hard to get at, under the car near the fuel filler & tank. With no Eolys, the DPF will clog with soot, even at 600C it may not burn off properly.

If the DPF has been on for more than 80k miles, it could well be blocked. Cleaning is an option, but make sure it is a type of cleaning that deals with ash, not just soot. The ash has to be washed out (reverse flush) by some means, it can not be burnt out in a kiln or by adding additives while on the car. Success of this process is uncertain. It usually gives an improvement, but I don't know for how long.

If you have to replace it, reports about the very cheap ones are that they are rubbish. May last less than a year.

Share this post


Link to post
Share on other sites
On 04/12/2016 at 5:24 PM, Tdci-Peter said:

And is the DIS_ASHFUL (or whatever it is) figure still going down at the 1km per km rate, with no big jumps?

Actually no after about a month this went back down to the 1000 - 2000 km range.. I don't monitor this as much but it's currently at around 1400 km and counting up. I guess this proves that it's not just a simple counter and is in fact based on some sensor readings.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now