ML320 CDi DPF location in the exhaust pipe?

[sr-performancelive..]

Your last Technician is wrong.. Your DPF has been deleted from the ECU mate and cannot put the MIL light on..

 

[ml320cdi]

what would you suggest as a next step?
thanks

 

[Alex Crow]

can you give us the specific fault code/s please, there are many possible ones relating to DPF issues...

 

[ml320cdi]

I didnt get a printout but I will bell the techy and see if his machine stored the info of the last run or perhaps get it put on the machine once more and get the error codes.

One question - If the ecu has been programmed NOT to detect the DPF, why would I still get the error codes?

 

[Alex Crow]

If the ecu has been programmed NOT to detect the DPF, why would I still get the error codes?

not my department i am afraid, but if you can give us the codes we can speculate further. if for instance ou have "DPF full/ash content too high" it certainly sounds like a problem with the DPF deletion.

the N3/9 ECU is indeed mounted between the wing and chassis at the rear of the wheel arch. WIS says it is on the RHS, but just as likely the LHS on a RHD car as electrics are almost always mirrored on RHD vehicles.

 

[ml320cdi]

thanks for the info AP
I'm going to the techy tomorrow and will get him to connect the machine once more and either take a print out or take a pic showing the codes and post here.

 

[sr-performancelive..]

Hi Alex,
He was getting this prob before the deletion, I have been in touch with Evolution and they say it will not put light on for definite.
Something not quite right, just one of those niggly probs!

 

[ml320cdi]

snapshot attached of the error codes

sounds like Evolution chips misled us then.. because I was told that the software will definitely delete the DPF from the ECU. I'm having to fork out money every time I get these checks done and I seem to back at square 1 again where I need to get the engine ECU taken out from under the front wing and take it to the technician who said they will delete the DPF by directly connecting to the ECU.

 

[Alex Crow]

the codes are all to do with the values from the pressure differential sensor. without knowing exactly how the DPF deletion mapping works it is hard to comment, but it is possible that the ecu still keeps a check of differential pressure values, but with perhaps a much wider accepted range. if this was the case, an open or short circuit DPS might still give you the problems you have. this is speculative as i have said.

the 2078 errors do suggest a DPS fatal error rather than a problem with the DPS values, did the garage do any further checks? the next step would have been to look at the values on live data, with ignition on and engine NOT running expect DPS value of around zero, ie <100hpa. after that it would be pin outs at the sensor and ecu to check if it was a wiring or sensor fault.

note that you have no DPF ash or soot content faults.

 

[ml320cdi]

do the errors suggest that the car is still in LIMP MODE.
2079-001 ( Engine protection active due to excessive signal voltage ) does that signify LIMP Mode activation?
--
previously, every time I've had the diagnostics connected, the technicians have followed through all the steps for clearing the faults and at the end its all been cleared and the yellow engine light on the dash has gone out BUT after roughly 15-30 min, the yellow engine light on the dash always comes back ON.

This time, I just asked the tech. to do me a print out of the error. The battery on his laptop was running low so he did it quickly for me. I didn't ask him to clear anything coz I knew the errors would come back on 15 min later.

I did notice that the ash content error is not there any more but the DPF is still throwing errors. Perhaps Steve could shed some light on how exactly the re-mapping is meant to work. I believe the DPF is an optional extra so the reprogramming is meant to simply make the ECU completely ignore the DPF and think that the car came without it.
All 3 errors above are to do with the DPF so the remapping obviously didn't delete it.

 

[Alex Crow]

I believe the DPF is an optional extra so the reprogramming is meant to simply make the ECU completely ignore the DPF and think that the car came without it.
All 3 errors above are to do with the DPF so the remapping obviously didn't delete it.

if your understanding of the deletion is correct then the errors should not be flagged as the ECU will not monitor the DPS.

it is not true to say however, that the errors are to do with the DPF as such, but they do relate to the DPS. i can only urge you to discuss it with steve and hopefully he can help resolve the question of how the deletion should work, and if the DPS is still monitored after the deletion.

yes, the code 2079-001 will give you reduced power.
yes, the code 2078-001/008 will put on the yellow light (as signified by the light bulb symbol on the line with the code).

as the codes 2078-001/008 are current, you have an ideal opportunity for proper diagnosis of the fault as i suggested, just erasing the code is fixing nothing...

from the codes you have posted it appears you have a faulty DPS, or possibly a wiring issue to the DPS. they are only around £25-30 for a new one, could be worth a punt?

 

[ml320cdi]

a proper merc specialist diagnosis leads to them asking for the DPF to be replaced. They will also see the downstream rubber hose disconnected from the DPF box and will most likely suggest that I put everything back together as it was previously, get a new DPF added and then they can proceed further.
a simpler solution will be to get the DPF removed from the ECU. I have asked another technician who is offering the DPF deletion service to check this thread and comment on it. This new tech says the the DPF can definitely be deleted from the OBD port and he writes his own software and assures me that it can be done so I'll wait until he adds some comments or perhaps Steve can offer a new solution.

 

[Alex Crow]

a proper merc specialist diagnosis leads to them asking for the DPF to be replaced.

not with those codes. they do not suggest DPF replacement, but rather DPS faults (ie signal voltage too high and plausibility).

 

[ml320cdi]

" plausibility error " could be connected to the fact that the downstream DPF sensor hose is disconnected and it must be noticing the fall in pressure.
If the hose is connected back up, the carbon content % in gases will go up and the previous error will start showing up again. In this case, changing any of the sensors is pointless.
I have now confirmed with 2 different technicians ( Pendle performance & FR-R Tuning ) that the DPF can be deleted via the OBD and that most tuning companies are just file flashers and they do not write their own software to enable them to delete the DPF.
I am now shopping around for the best quote for the DPF delete ( currently £250 from FR-R )

 

[Alex Crow]

having the downstream hose disconnected will give approximately correct DPS values, and not this error. also note it is 'plausibility error with ignition ON' ie before engine starts. in this scenario the DPS will not be reading ANY differential pressure whatever the hoses and DPF (or not - yours is removed) are doing. this is because without the engine running ther will be equal pressure either side of the DPS, giving a differential pressure of zero.

reconnecting the hose will not cause carbon content % to be logged as too high because the DPF content is missing - unless the DPS is defective.

i can only draw your attention to my previous comments regarding the nature of the fault codes you have. the text 'signal voltage too high' is a starting point, and suggests a sensor fault more than anything else. and yes, we might reasonably expect that you would not get any of these fault codes with a 'DPF deletion'.

 

[M80]

I've returned to this thread looking for a possible answer to the engine light / safe mode problem on my 220 CDI.

I'm booked in at MB Mansfield for Monday but the possibility of saving myself a journey and dispensing with the DPF has appeal.

I see ML320's photo describing the downstream sensor on the DPF, surely this is a tapping point with pipework that feeds to the sensor ?

In normal running both sensors ( upstream and downstream pressure sensors ) will see a pressure, albeit at slightly different pressures.

When, due to excessive blockage, the upstream sensor sees a higher pressure than the downstream ( the differential ) the ECU will cause regeneration by causing more fuel to be injected into the system, higher resultant temperature in the exhaust (namely the DPF) should clear the build up of soot.

If the differential pressure is outside parameters the ECU flags as a fault and causes safe mode.

ML320 has blanked the output to the downstream sensor near the exhaust, and left the feed into the sensor open to atmosphere. He still has faults.
Although the upstream sensor will show lowish pressure (due to the DPF being removed) it will still be higher than the pressure at HIS downstream sensor. It seems reasonable to expect a differential when the engine is running.

My thoughts are to 'blank the output to the downstream sensor near the exhaust' as he has done.
But 'T' the feed to the downstream sensor into the feed to the upstream sensor. Both sensors will then be fed from the upstream tapping point from the DPF.
There will be no differential pressure and no need for the ECU to cause regeneration.

This is dependant on the DPF guts being removed.

Would the DPF system still need to be deleted from the ECU ?

Will the ECU see a fault condition if there isn't at least a small differential ?

Please correct me where my thoughts are just not correct or feasable

 

[Alex Crow]

I've returned to this thread looking for a possible answer to the engine light / safe mode problem on my 220 CDI.

I'm booked in at MB Mansfield for Monday but the possibility of saving myself a journey and dispensing with the DPF has appeal.

I see ML320's photo describing the downstream sensor on the DPF, surely this is a tapping point with pipework that feeds to the sensor ?

In normal running both sensors ( upstream and downstream pressure sensors ) will see a pressure, albeit at slightly different pressures.

When, due to excessive blockage, the upstream sensor sees a higher pressure than the downstream ( the differential ) the ECU will cause regeneration by causing more fuel to be injected into the system, higher resultant temperature in the exhaust (namely the DPF) should clear the build up of soot.

If the differential pressure is outside parameters the ECU flags as a fault and causes safe mode.

ML320 has blanked the output to the downstream sensor near the exhaust, and left the feed into the sensor open to atmosphere. He still has faults.
Although the upstream sensor will show lowish pressure (due to the DPF being removed) it will still be higher than the pressure at HIS downstream sensor. It seems reasonable to expect a differential when the engine is running.

My thoughts are to 'blank the output to the downstream sensor near the exhaust' as he has done.
But 'T' the feed to the downstream sensor into the feed to the upstream sensor. Both sensors will then be fed from the upstream tapping point from the DPF.
There will be no differential pressure and no need for the ECU to cause regeneration.

This is dependant on the DPF guts being removed.

Would the DPF system still need to be deleted from the ECU ?

Will the ECU see a fault condition if there isn't at least a small differential ?

Please correct me where my thoughts are just not correct or feasable

nice working, but you have started with incomplete information.

there are not 2x pressure sensors either side of the DPF, but actually just one DIFFERENTIAL pressure sensor that gives a pressure DIFFERENTIAL reading between upstream and downstream ports on the DPF. this means the ecu only knows the differential pressure, NOT the absolute pressure. there IS an exhaust back pressure sensor upstream of the VNT, but this bears little or no relation to absolute pressure downstream of the turbo, and can read 3bar or more depending on engine running condition. on a 2005 C220cdi with DPF fitted, removing the DPF monolith will trigger differentiual pressure fault codes due to lack of pressure differential (even with a clean DPF it expects to see some reading from the DPS). on this car venting the down stream port to atmosphere will give a differential reading between the upstream port and atmosphere, which works well at fooling the ECU that the DPF is still fitted and working fine.

note that the 'extra fuel' injected to clean the DPF is injected on the exhaust stroke, and is associated with fuel dilution of the engine oil in vehicles with badly soiled DPF (ie ash, not soot, ash cannot be automatically regenerated whereas soot can). this is happening with other makes of car fitted with DPF also.

 

[ml320cdi]

an update from my side - I have almost become completely fed up now with trying to resolve this issue. These so called DPF software delete experts all seem to just be talking nonsense. I tried another technician ( FR- Tuning ) who after reading all these comments told me that he was 100% on removing the DPF from the ecu. I paid them a visit, he connected the machine to the OBD port and after 2 min of work told me that the DPF had been deleted from the ecu. I checked the dash and the yellow engine light was still there. The technician told me that the light would go off after a few miles of driving and I had to pay him £250 to leave the premises. I knew it was just utter nonsense.. I asked the technician to come out on a drive with me and we could check but he started making excuses.
It seems like these technicians are just making false claims about being able to remove the light just to make some quick money. I told the technician that I knew the light wouldn't just go off after a bit of driving and asked him to reverse whatever he did so i don't have to pay him. We eventually settled with me paying him £50 so I could leave the premises and get back to the technician later to try something else to get the light off. I simply have no trust in these technicians to go back to them.
There is a few other technicians also making similar claims that they write their own software etc and they can definitely take the light off BUT I simply don't have any faith now after spending so much without a result

I am now leaning towards getting the engine ecu taken out from under the passenger side front wing and getting the original technician to take a look at it. My advice to people here is not to trust any technicians who tell you that the ECU dpf light can be switched off from the OBD connector. They will simply run a programme which may take the light off for 15 - 20 min BUT it will come back on again and you will have forked out money for nothing.

 

[Alex Crow]

an update from my side - I have almost become completely fed up now with trying to resolve this issue. These so called DPF software delete experts all seem to just be talking nonsense. I tried another technician ( FR- Tuning ) who after reading all these comments told me that he was 100% on removing the DPF from the ecu. I paid them a visit, he connected the machine to the OBD port and after 2 min of work told me that the DPF had been deleted from the ecu. I checked the dash and the yellow engine light was still there. The technician told me that the light would go off after a few miles of driving and I had to pay him £250 to leave the premises. I knew it was just utter nonsense.. I asked the technician to come out on a drive with me and we could check but he started making excuses.
It seems like these technicians are just making false claims about being able to remove the light just to make some quick money. I told the technician that I knew the light wouldn't just go off after a bit of driving and asked him to reverse whatever he did so i don't have to pay him. We eventually settled with me paying him £50 so I could leave the premises and get back to the technician later to try something else to get the light off. I simply have no trust in these technicians to go back to them.
There is a few other technicians also making similar claims that they write their own software etc and they can definitely take the light off BUT I simply don't have any faith now after spending so much without a result

I am now leaning towards getting the engine ecu taken out from under the passenger side front wing and getting the original technician to take a look at it. My advice to people here is not to trust any technicians who tell you that the ECU dpf light can be switched off from the OBD connector. They will simply run a programme which may take the light off for 15 - 20 min BUT it will come back on again and you will have forked out money for nothing.

sorry to hear the trouble continues - what was the final position with S.R.Performance?

 

[ml320cdi]

sorry to hear the trouble continues - what was the final position with S.R.Performance?

I think S.R also just gave up saying that " its one of those tricky things which he couldn't resolve. "
the point I'm making is that all the different technicians seem very confident before taking on the job so it may be a good idea to make it clear to the technician that if the light comes back on, you won't be paying.

I will update everyone here once I get the engine ecu taken out and let the technician work on it. The first technician did say that the dpf delete cannot be done via the OBD port and you need a direct connection to the engine ecu.