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DPF info

26K views 51 replies 14 participants last post by  Bus-man 
#1 ·
I've got a dpf light & trying to get info on how to fix it.
I've driven 25 miles at over 3000 RPM & sat stationary for 20 mins at over 4000 RPM
Light still on
I understand the idea is get the dpf at a high temperature to burn off the carbon
Gone through a lot of the posts, but a lot of stuff seems to be opinions rather than facts.
Trying to find out what's important during dpf regeneration: -
1.) Does road speed matter? My feeling is that engine RPM to bring dpf to high temp is what matters
2.) Can I just park somewhere that's not annoying to anybody & just rev till the light goes out?
 
#2 ·
The service manual states:

When DPF warning light lights up, drive the vehicle under any of the
following condition to complete regeneration.
• The vehicle is driven continuously at 60km/h for 30 minutes*
• The vehicle is driven continuously 15km or more without being
caught in traffic jam
If the vehicle is driven in the driving pattern in which the exhaust gas
temperature can not be raised after DPF warning light lights up,
ECM performs the following to protect DPF.
• ECM enters fail-safe mode and limits engine speed to 3,000 rpm with fuel cut.
• ECM stores DTC P2002 in the memory.

I have found doing 50mph in 5th down the motorway works.

Nick.

Sent from my SM-G920F using Tapatalk
 
#4 ·
I have no specific experience of T31, but have worked on this on various VAG and PSA cars.

All internal combustions engines get hotter the harder you work them. However, diesel engines also produce more soot, the harder you work them. Getting exhaust temperature high is key to burning off the soot accumulation in the DPF. If you have an open fire at home, you'll often see that the back of the hearth, closest to the hottest part of the fire, is relatively free of soot - just clean firebrick, whereas the parts of the hearth that aren't as hot, have a significant soot accumulation on them. Whilst working the engine hard is good for getting the exhaust temperature up, it is also bad for generating more soot - the very thing you're trying to get rid of!

The trick, therefore, is to get the engine working JUST hard enough to get the exhaust hot enough, but not so hard that it generates soot. For most engines, that is surprisingly LITTLE work! People who tell you to "thrash it" down the motorway are likely to be simply adding to the problem. In the above recommendation, 60 km/h is only about 40 MPH. The important thing is NOT TO STOP AND LET THE ENGINE IDLE during that time, because it only takes a minute or so for the exhaust to cool down and spoil the regeneration.

Most cars will have engine management strategies that try to increase exhaust temperature when doing a regeneration. They'll fiddle about with EGR settings - possibly injector timing and duration too. They'll do "whatever it takes" to get the exhaust stinking hot for that period. Running the engine at high revs under no load probably won't help much unless it has been put into a "forced regen" mode, where the engine management system can then "do its thing", but driving it under light engine load is better.

Of course, if there is something wrong with your car and some part isn't working so as to allow the thing to go into regen mode, then you might be doomed in your attempts to get it to regen.
 
#5 ·
My experience is very recent and has a happy ending...

The light came on a couple of days ago and I fretted a bit that night whilst researching remedy and reading what is in the manual.

Next day I took her out onto the A69 and kept the revs at 2000-2500 on cruise control and within about 10 Miles ( so about 10 minutes) the light went out. No need for thrashing the engine nor getting her super-hot, just steady and that worked fine.

So I agree with Avocet's more in depth technical description of what is required.

Good luck, I hope yours is as easy...

K ;-)
 
#6 ·
I've had 4 long runs with no results at clearing dpf light. I have elm32 blue tooth OBD connector & various Android apps, but none show DPF temp & pressure data. I would like to see evidence that DPF regeneration temperatures are being achieved. Has anyone managed to get apps that show x-trail dpf data?
 
#8 ·
the X-431 app does have it, but it requires it's own BT adapter.
When the cleaning process is started, then the x-trail injects fuel at the exhaust stroke. Hot exhaust gasses and little unburnt fuel ignites and burns even hotter in the catalytic converter.
My theory is that the shoot appears when the engine temp and engine revs are low. Heat comes from fuel, fuel comes when the acc pedal is pushed.
When i did my engine rebuild on my T30 and after that a Cyl head replacement and valve regringing, the exhaust valves where clean. So shoot and carbon appears after combustion chamber where the temps are coming down.

EE has a great video
 
#10 ·
I've had my Xtrail for about 3 years now and the light comes on periodically. Sometimes it takes a few miles of high ish rpm driving to clear it other times I'm going for 45 mins. The other day it came on when leaving work and after getting the engine up to temperature I ended up sitting in a traffic jam for 5 mins moving slowly in 1st and second gear and that cleared it. Another time I was waiting at the side of the road (idling) waiting for a gap so I could get a clear run on the road I normally use and that cleared it!

My normal method is a clear run in 4th at 50-55 mph in cruise control and it usually takes 7-10 miles to clear.
 
#11 ·
I must be doing something right as driven car for some 2000 miles now since purchase in Dec and never had the light come on. I do however live mile and half off dual carriageway; Norwich bypass A47 being one way and Thetford the other with one roundabout so engine does warm up nicely. I do often do long runs as well i.e Manchester and back in day 560 miles at constant 70 -75 in cruise. Oddly it was due to dpf problems why I sold my Saab 9-3 TTiD estate which are renowned for being good - mine must have had underlying issue but so far no DPF light and I always use Shell fuel (2 garages pretty close to me so why not).
 
#12 ·
Long time since Ive been on here but have now got the dpf light on and previous drives do not clear it this time. Now MIL light has joined it... am I heading for a problem or can I still fix it by driving steady for a while?
DPF additive has not helped and have just filled up with BP Ultimate at 143.9 per lit. - ouch!
That has not cleared it either...
Any further advice? EGR valve?
Cheers
K ;)
 
#13 ·
Not long after buying my T31 last August, I had the DPF light come on followed fairly soon after by the EML. Driving as recommended didn't clear it, so I took it to my local garage for a forced-regen. Got it back running fine with no lights on. It has come on a few times since, but each time a run of 20 - 30 minutes continuous at 50 - 60mph keeping the revs over 2,000 has cleared it. Being an automatic, unless driven hard it tends to keep the revs low which makes it a nice quiet drive, but to do a regen I find that I have to put it in manual mode to keep the revs over 2,000rpm.

I am inclined to think that once the EML comes on too it is time for a forced-regen, but if you can take it for a continuous run as I described above before the EML comes on, it should clear. I may however be wrong as I'm no expert, I'm just going by my own experiences as this is the first vehicle I have owned that has had a DPF.
 
#14 ·
It feels like it has done a regen as its not stinking hot and the mpg has recovered to mid 30's from the low 20's. All running and feeling fine, but of course the two lights are still on. My OBD2 reader wont read anything cannot connect to vehicle... im sure it has in the past.
So do I need to have a forced regen now then and at what cost? Do you think an independant could do it or is it a Dealership job? Nearest one is ****** miles away
K :(
 
#15 ·
bertye said:
If your egr valve is not shutting fully (it should as the ECU shuts it down to be able to regen), then there is no enough oxygen to burn the soot out. The cleaning map will then just make it worse.
As a short term fix, could I temporarily blank the egr to simulate a fully closed egr valve? I am assuming here that my normal drive did not clear the dpf light due to an egr valve not fully closing per your post due to soot build up. I dont want to try to remove the egr to clean it during the Christmas holidays but can see the flexi pipe of the egr would be pretty easy to access and blank off temporarily until I have more time to clean it properly.
Or is it too late now anyway now the MIL has also come on?
K :(
 
#18 ·
Bu99er it, its parked up until after the fat mans visit then I will look at it again. Fairly resigned to a Nissan rip off regen charge but not to a replacement dpf.
Will take it to local indy to see if they can help... shy bairns get nowt.
Merry Christmas everybody
K ;)
 
#19 ·
malgpz900 said:
Are there any telltales on the Xtrail to say it's regenerating?
Had a Pug 407 before and the heated mirrors used to heat up when it was regenerating. Owners wired a small LED across power to heating element which would glow when regenerating.
Malcolm.
Yes, it stinks like a burning clutch or brake and fuel consumption doubles.
No visual indication, just the dash light when it fails
K :(
 
#23 ·
What i have read in local forums that the pressure washer cleaning works 50:50. Theh do a diagnostic but moust of the times they do the the cleaning anyway to get the money.
On a Transit it worked for a month, but after that the dpf with an aftermarket one, wich costed like 350€. Same as the cleaning.
 
#25 ·
Can't think why a glow-plug would stop a regen. Surely the are just for starting a cold engine?

When I had a DPF light and EML come on, a local Indie did a forced regen for me with no problems. I have had the DPF light come on a couple of times since, but a good run of about 30 minutes soon puts it out now. It didn't before the forced regen.
 
#26 ·
I had that trouble when I first got my '08 - and eventually the light wouldn't go out - Nissan dealer wanted £250.00 to purge it - and said it might need doing every 2-3 months! I did some digging and eventually found a firm that removed DPFs. Had it taken off and it's been trouble-free for the past 8 years - sailed through every MOT with emissions as clean as a whistle - last one a few weeks ago.
 
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