Engine: D5: Limp mode after warm up, DPF regen and fuel filter changed

[outnumbered]

you can test the sensor with your knock of kit when it arrives or are you still going to the dealers with the possibility that you may get shafted on the further investigation
mike

[Appletree]

Matts Dad here again, feel inclined to cancel Volvo visit, there are no live fault codes at present. I could chance it and buy a new DPF sensor outright for no more than Volvo visit. Seems on quick search same part for Ford Mazda and Volvo
As we are getting good back pressure from particulate filter I doubt it has burnt out although I suppose it could have collapsed (although i would expect that to give DPF blocked signal).

Tending to suspect DPF sensor or previons signal pipework blockage which we have now cleared, at start of fault 10 days ago fault incidence was far more random than lattery up untill todays work.
Regards Phil

[outnumbered]

if it was me i would test the sensor and go from there you can always re book the dealer
mike

[Appletree]

Hi Matts Dad again.
Thought it might have been mended but no. Waited for car to be cold when i turned ign on came up with ENGINE SYSTEM SERVICE REQUIRED (and yes I know I am shouting LOL) turned ign off and back on message cleared, turned ign off and back on message came up again.
Started engine, reved slightly message cleared set off ok after 200 yds went into limp mode did 10 miles still in limp mode.

I am an Instrumentation Technician in the power industry and have access to test equip.
Although Volvo have tried a New or second hand DPF sensor (I was told both), I do not trust the one which is fitted and want to get back to basics.

So some questions
1 As the car drove fine for 20 odd miles after our pipework checks today without any probs.
Is the ENGINE SYSTEM SERVICE REQUIRED message being generated from faulty ECU inputs when ignition turned on before the engine is started.
Or is it a function of the last journey and additional stored codes in ECU. Especially as the message was not there when the car returned from its last drive, nor when I turned the ignition on between trips.

2 What are the DPF sensor pin connection duties? ie supply, analogue ouput etc?

3 What value of differential/back pressure should I get from DPF at tick over given revs etc?

4 Is there a table of analogue o/p versus diff pressure?

5 Any other ideas?

Thanks in advance Phil

[Appletree]

This guy seams to have the same as us, and fixed it with a new DPF sensor, as said we're waiting for the kit to arrive so we can read and clear the code correctly.

http://www.volvoforums.org.uk/showth...=limp+mode+v50

[Clan]

Originally Posted by Appletree

Hi Matts Dad again.
Thought it might have been mended but no. Waited for car to be cold when i turned ign on came up with ENGINE SYSTEM SERVICE REQUIRED (and yes I know I am shouting LOL) turned ign off and back on message cleared, turned ign off and back on message came up again.
Started engine, reved slightly message cleared set off ok after 200 yds went into limp mode did 10 miles still in limp mode.

I am an Instrumentation Technician in the power industry and have access to test equip.
Although Volvo have tried a New or second hand DPF sensor (I was told both), I do not trust the one which is fitted and want to get back to basics.

So some questions
1 As the car drove fine for 20 odd miles after our pipework checks today without any probs.
Is the ENGINE SYSTEM SERVICE REQUIRED message being generated from faulty ECU inputs when ignition turned on before the engine is started.

yes as the reading expected then should be zero

Or is it a function of the last journey and additional stored codes in ECU. Especially as the message was not there when the car returned from its last drive, nor when I turned the ignition on between trips.

2 What are the DPF sensor pin connection duties? ie supply, analogue ouput etc?

the 3 wires are : earth , 5v in and an analogue voltage out 0 - 5 v depending on pressure .
3 What value of differential/back pressure should I get from DPF at tick over given revs etc?
no , but i did list them in a post above , pressure rather than voltage i am afraid .

4 Is there a table of analogue o/p versus diff pressure?
alas no , but goes up with rpm

5 Any other ideas?

seeing that FORD sensor i wouldnt hesitate in changing it , these play up quite regularly on the V50 2.0 D they seem to have a lifespan of about 70000 miles .
However on the D5 they are fairly trouble free in practice . On the later D5 it is interesting to see they have a BOSCH particle filter sensor .
Thanks in advance Phil

I hope that helps

[Appletree]

Hi all bit of a PITA but car can stand for a week or two. Now releying on the dog walking charriot (P plate peugeot 106 115k) awaiting Vadis reader. Inclined to check out PDF pressure sensor and renew more than likely. Considering clean of DPF with cleaner chemical (remove dpf and soak) and/or pressure washer back flush.

Will keep posted Phil (Matts Dad)

[outnumbered]

keep at it you will get there once you get the kit, plus if it works out you will have the satisfaction that you do not have to go to the dealers all the time infact the only time i go to the dealers is for the software upgrades as and when.
mike

[Appletree]

Right Today I decided to grab the Nettle. I sorted out my pressure measuring equipment which has suffered battery wise through lack of use, but got it going after a fashion. Reasonably confident results acurate although reading swinging a couple of Hpa at rest the results as follows.

Volvo diesel particulate filter readings taken on each DPF port in turn with the other blocked off at given RPM and the differential pressure calculated.

RPM BEFORE DPF Hpa AFTER DPF Hpa DIFF PRESSURE Hpa
800 10 negligible 10
1500 40 negligible 40
2000 40 7 33
2500 90 30 60
3000 210 70 140

It would appear that the rear silencer system is restrictive as at low volumes there is no back pressure on the rear tapping of the DPF however both readings rise rapidly at higher RPM and flow rates.
The gas flow and thus pressures will be much different under load give that these figures were obtained with the car stationary.


So where to now the DPF apperars restrictive but so does the back box, Do I ?

Back flush DPF
Buy new Volvo DPF
Buy aftermarket DPF
Investigate if rear silencer faulty


The idea of DPF removal is attractive as the DPF system is bad news however there are the insurance/modification issue, MOT and Legal issues.

I probably still intend to keep car I have hjad it 4 years.

The irony of the whole DPF thing is that they are not suitable for use where the greatest benifitt of clean combustion is required in towns.


Thoughts Please Phil

[Clan]

The differential readings are a little higher than you would expect with a freshly regenerated particle filter from my experience. But the only official test figures are 3 - 20 Hpa at idle which yours is comfortably within .
I think i would try and borrow a known good sensor or just buy a new one first especialy as you think it hasnt been off before for substitution .
Remember the Differential pressure will not be affected that much if a rear silencer was restricted of course . This is very unlikely in practice .