[LvR]

What scan tool are you using?


Cannot tell you how many MB DPFs I have ripped off the car, cleaned it manually, refitted it and the same MB dealership that wanted to condemn the DPF because it wouldn't clean up after a regen, and replace it at exorbitant cost to the owner, the next time the vehicle landed on their doorstep for a service, suddenly commented that its good to see the replacement DPF they recommended, sorted the moans on STAR the last time it was there.............. on my own STAR I have seen the DPF go from 189g soot to just 3g with a manual clean off the car (320 CDI with around 170000km) ................. and a forced regen via STAR doesn't seem able to lower that any further after having just installed the manually cleaned DPF.



So - before you get the DPF replaced know this:


If the ECU logic cannot see how to safely do a normal regen or a forced regen, then a regen is going to fail or not happen................. it depends on these items among others



1. You still need enough flow through the nearly "blocked" DPF to allow the extra heat and converted ash rubbish generated from a "regen" to be blown out the exhaust
2. You need an exhaust (excluding the DPF) to not be limiting factor ito back pressure (eg no silencer box with broken baffles hassling flow) - The ECU monitors the pressure differential across the DPF (read no associated blocked tubing and pressure sensor on the DPF, and also most importantly, a varying signal from the pressure sensor in sympathy with the engine speed and load), and uses that as well as the absolute exhaust pressure after the DPF to figure if the mechanicals involved are safe and not going to cause a possible fire.

3. Engine speed elevated off idle - typically 1500rpm +





IMO a blocked DPF is a mechanical condition/state as a result of the inability to convert and expel the accumulated soot (DPF's function in life) as harmless ash out the exhaust at the back of the vehicle

 

[LvR]

Sounds right that yes


What scan tool are you using?


Do you have access to a Clip or something that can monitor and log every parameter on the EGR and DPF system at all?

 

[LvR]

Not all scanners can access all parameters and I dont know the particular one, but I would try to monitor and log all exhaust temp and pressure values.

the dpf temp sensor reading seemed to be stuck at 50

C?


If so that's virtually impossible - if the DPF is flowing anything at all (engine runs so it obviously must) there should be very little temp drop/difference across the DPF - think like this - can you touch the location of the downstream temp sensor? ........... at 50C you should be able to without burning yourself. Exhaust temps should very quickly reach 200C (not touchable without burning) at idle even and easily go towards 400C+ when going down the road.


The regen request is obviously picking up on the fact that there is apparently no flow and thus pukes.


This off-course also assumes the scanner is actually reporting proper temp values. Any chance you have an IR temp gun you can point at the locations of the temp sensors around the DPF to correlate values?




The 60g soot content is basically a useless figure and should be ignored untill ALL parameters around the DPF is getting measured properly/normally ................. IN THIS CASE ..............and is a calculated value determined from the differential pressure, absolute pressure after the DPF and temperature reading the ECU is seeing around the DPF (fancy maths determined by Renault engineers - I doubt anybody has exact equation)

 

[LvR]

FWIW - the ScenicII manuals I have here (should be fairly universal ito the theory) are speaking of the pre and post DPF temperatures that are apparently monitored in order to trigger auto regen - both around 600C before an auto regen will get triggered.
The differential pressure (when measured properly by working pressure sensor) is an indication of the soot content - I cannot find absolute values here to quote, but I have seen up to the low several kpa order numbers for differentials on MB diesels I have had here.


This manual speaks of 45g soot requiring a manual regen to silence the moan on the dash.


So your 60g .................. yes its a value reported yet at the same time you say its mechanically clean? ........................ brings differential and absolute pressure measurements into question (did you check the sensor, tubes, connectors for cracks,breaks, blockages? ................ what Ours is suggesting there).................... see again my comment earlier re manual mechanical cleaning if you are 100% sure they are all pristine and working

 

[LvR]

i have had another look at the live parameters at idle, see attached samples , there is a difference between the readings of the temp sensor before the turbo and the one in the fap, it seems to be around 25c, the one in the fap reading lower (110c in the attached sample data file a) than the one before the turbo (135c). Should these figures be more similar, ie the sensor in the exhaust misreading?

Ok - those temps are much more believable.


Can I suggest you keep the revs at around 1000 for say 5 minutes then take another batch of readings .................


There is a bunch of exhaust metal involved with huge thermal masses that will cause temp difference at too low a flow between those 2 sensors (losing heat to environment faster than exhaust flow can heat the metal and there is a bunch of that heat converted to pumping energy on the turbine too)............... FAP temp in theory should therefore always be lower than pre-turbo at very low flows.


First reaction? .......... if you are 100% sure all the associated plumbing and nipples/nozzles are clear then think you have a duff pressure sensor or the situation I mentioned before. Lets see with a hot flow set of hot flow values

 

[LvR]

From that there is absolutely nothing I can identify as being the culprit - perhaps I just am not familiar enough with Renaults yet and one of the founding fathers of the site will chime in to say where my logic is failing.


What you can try is this:


The 2 tubes running to the dp sensor on the FAP - plug the tubes on the exhaust/FAP side and leave the nipples on the actual pressure sensor open to atmosphere ................. now start the engine and report the differential pressure seen with the sensor open to atmosphere ............... dp should be close to 0 - if it is (and you will now probably get moaned at with a different error about non plausible pressure values but ignore), then I am afraid its back to my first suggestion

 

[LvR]

yep

 

[LvR]

I have never done a Renault FAP ..............on the MBs I have done I removed the FAP from the car and with a high pressure car cleaner (Karcher etc) and while using a broad fan nozzle at about half pressure (adjust spray pattern on nozzle) clean out all the loose debris you can while trying to blow down the little tubes you can see (its going to get real dirty around you ) - first from the inlet side and then in the reverse from the outlet side, repeat till see nothing coming out - make sure you try and cover each individual tube/channel. Now block the intake side and make it water-tight. From the outlet side pour liquid engine cleaner into the FAP . Go bother the wife or a case of beer while it sits overnight. Next day again use the high pressure cleaner to mechanically clean the thing from both sides alternatively till no dirt comes out. Once happy stand it on end in the sun and go have a beer - if you think its dry refit and experience bliss.


BEFORE you do this though .................... whats the result of the dp reading with the pressure sensor open to atmosphere I asked about before and are you 100% sure all of that small diameter plumbing including the nozzles and nipples are open and unblocked with no cracks on there at all? ............... is the scanner reading close to 0?

 

[LvR]

I really think you need to re-read the whole thread again and understand that an error code is not an instruction to replace a specific sensor or component even if that sensor is mentioned in the error code - the error code is telling you that the ECU is detecting values on a parameter off a sensor that is not as expected .........................


The sensor itself can be faulty but often is not .................


The sensor can be ok and a horde of items affecting the sensor's readings may be causing the sensor to report funky readings.


Again - a blocked DPF/FAP, if properly identified, is a mechanical condition/state that can be fairly easily and cheaply rectified without resorting to replacing unnecessary sensors or DPF/FAP exactly as per your original enquiry

 

[LvR]

Never had to do one myself on this motor so cannot comment, but from https://www.ebay.co.uk/itm/Renault-...III-08-15-1-5-DCI-K9K-DPF-Diesel-Particulate-Filter-Cat-Converter-/272853447890 it sure doesn't look like cutting is involved ................. perhaps on yours the fitting technique was specific and different for some reason?

 

[LvR]

:iagree:

 

[LvR]

Fit it and see ..................:surprise:




THIS is exactly why I commented to use a broad fan spray pattern at low pressure - you used a needle pattern there https://www.renaultforums.co.uk/4211357-post23.html

 

[LvR]

If all the broken pieces are out of the flow path, then mechanically I doubt it will cause you drama. If you check and confirm the pressure sensor port/tube/pipes and actual sensor is clean and ok, then chances are it will still work - you will have a reduced efficiency/capacity of the cat though. Id say assemble and test - DPF part is bound to be sorted - at worst you are now at the point where the garage was initially............... iow to replce the dpf.


This experience will be very good reference for future readers - would appreciate your further feedback if you do fit and try it

 

[LvR]

So you have DECaTTED it then, just fit knowing you are never gone to have the problem again.
but dont tell MOTer,, LOL

Watch the horde of new threads appearing here now on THAT subject!:laugh:

 

[LvR]

particle filter differential pressure ..................... down from 55 to 5 .................nice!:grin2:


Drive the thing and see - dont expect a regen every trip.


Sort the injector ................... its going to possibly again clog the dpf and prevent the start of auto regens and even prevent manual regens.:frown2:


Regen WILL NOT happen with most ECU errors present

got 'stop' message and fault code for the temp sensor within 500 mtrs

? .............. which temp sensor what exact code? ........... you may be right - some moisture still needed to get burned out of a hidden pocket somewhere


You need new oil!

 

[LvR]

Just me ................. never ever try to start a regen if there are any ECU faults logged - sort/clear them RELIABLY first.


They can and do screw with regens - that's why I said you need new oil after seeing your parameters earlier

 

[LvR]

Remember to clear oil wear/timer before driving/doing anything after oil+filter change.


If at all possible don't do a forced regen ........... drive the thing and let technology manage itself

 

[LvR]

Glad it worked out.



I am all for keeping reference data on particular engines - this is a good example for you to have a known good working set of values for the animal

 

[LvR]

Describe the subjective feel of the engine ............. quick to start, economy, power, hot or cold operations?..............


The initial fuel dilution rate is much higher in fresh oil than in used oil - if you draw a curve of dilution measured against distance traveled you will see this characteristic - its something oil labs warn owners of even petrol DI engines in particular.


You are not wearing anything out with normal regens .................. its going to be a function of the capacity of the DPF and the success of the logic built into the ECU and most importantly your driving environment and style . ............. I dont know what the normal frequency of regens in city driving is for a Renault or any engine, but would think your report at this stage sounds totally normal.


Lets see if there are any other **** data gatherers like me that can report on personal experiences with the same engine in the same driving conditions.


This all just goes to show how critical it is to keep MILs off on the ECU so that normal regens can happen when the ECU wants it to happen else you end up with your initial problem