W212 E350 CDI Regeneration Issue

[Aston Dabb]

Hi everyone,

I have a W212 E350 CDI.. it seems to be doing a DPF regeneration too frequently. I hooked it up to the star machine a couple of days ago and found that the soot content rises insanely fast whilst driving! I also noticed that the temp sensor upstream of the Cat. Just after the turbo absolutely shoots up upon acceleration. I got another technician to do some tests and we decided to bite the bullet and replace the DPF, lambda sensor (which was absolutely lathered in soot) & pressure sensor. One day into the new DPF; it’s regenerating again! It seems to do one every other day. No EML, no Lack of power; just regen after regen after regen!!

 

[mioba]

Have you actually had any fault codes triggered which led you to pull out star and change things.

 

[mersum1es]

Is your boost ok, are injectors solid (no peeing into cylinder)? Sounds like DPF is getting so much stuff it is filled up in hours (= smokey exhaust = insuffiecient amount of air compared to fuel)

 

[Aston Dabb]

Have you actually had any fault codes triggered which led you to pull out star and change things.

No fault codes in CDI at all.. and everything is within specified values in actual values also as far as DPF Actual Values go

 

[Aston Dabb]

Is your boost ok, are injectors solid (no peeing into cylinder)? Sounds like DPF is getting so much stuff it is filled up in hours (= smokey exhaust = insuffiecient amount of air compared to fuel)

Boost is bob on; I used the proper MB tool to check for boost leaks; pressurised the system and absolutely nothing; as far as injectors go I haven’t pulled them out and tested them but there are no symptoms of a faulty injector?

 

[LostKiwi]

You need to find the cause of the soot. The DPF can't cause soot so no idea why you changed it.

Excess soot can only be the engine is receiving too much fuel for the air being consumed.
Boost leaks are the usual suspect - the pipes from turbo to intercooler and intercooler to manifold split. It can be very hard to see the split. Intercoolers can also rot or get holed.

Check ambient air temperature sensor readings. If it thinks it's -20 it will inject more fuel than it needs and generate soot.

 

[mioba]

Althought I agree with you LK, what you describe would at least trigger codes. OP has your car been remapped

 

[Botus]

when they get to clogged the DPF can't manage its automated regen cycle on its own. with average diagnostic kit you can force it to try in the workshop. but the system didn't work well from build, so this is mostly pointless - hence the very low success rate .

There have been multiple attempts to make it less unreliable with various sensor and software updates (that the vast majority of independent garage can't apply), so it not going to get fixed by 98% of merc specialists ever and never ever by a non merc place and certainly not at home by anyone

The right thing is later sensors, later software and a manual clean of the DPF. There is more than enough info on this forum and every other merc forum to understand all this and we should all stop reply to these waste of time posts and just put one sticky togehter.

if you own a Merc Diesel that came with a DFF (that must work to get the MOT) and you have lights on the dash, its almost 100% likely it needs later software (and very few of the best specialists can do this for you).

 

[Aston Dabb]

when they get to clogged the DPF can't manage its automated regen cycle on its own. with average diagnostic kit you can force it to try in the workshop. but the system didn't work well from build, so this is mostly pointless - hence the very low success rate .

There have been multiple attempts to make it less unreliable with various sensor and software updates (that the vast majority of independent garage can't apply), so it not going to get fixed by 98% of merc specialists ever and never ever by a non merc place and certainly not at home by anyone

The right thing is later sensors, later software and a manual clean of the DPF. There is more than enough info on this forum and every other merc forum to understand all this and we should all stop reply to these waste of time posts and just put one sticky togehter.

if you own a Merc Diesel that came with a DFF (that must work to get the MOT) and you have lights on the dash, its almost 100% likely it needs later software (and very few of the best specialists can do this for you).

I work at MB Truck & Van and as mentioned above i have already plugged it into the star machine & have updated CDI and VGS to the latest software; I have also already changed the pressure sensor

 

[Aston Dabb]

You need to find the cause of the soot. The DPF can't cause soot so no idea why you changed it.

Excess soot can only be the engine is receiving too much fuel for the air being consumed.
Boost leaks are the usual suspect - the pipes from turbo to intercooler and intercooler to manifold split. It can be very hard to see the split. Intercoolers can also rot or get holed.

Check ambient air temperature sensor readings. If it thinks it's -20 it will inject more fuel than it needs and generate soot.

We changed the DPF as we found was damaged due to the constant regeneration. It has been doing this for thousands of miles. There are 100% no boost leaks as I have used the Mercedes tool as per a WIS document to find a boost leak there is absolutely nothing

 

[Aston Dabb]

Althought I agree with you LK, what you describe would at least trigger codes. OP has your car been remapped

Car is not mapped; I have updated CDI but not made a difference to DPF issue

 

[Aston Dabb]

Hi all, we are now 1 month later and yet no further with this DPF regeneration issue; I had a chuffing injector last week so I decided to get all 6x injectors tested; the chuffing one failed but the rest passed so I purchased a new genuine injector, taught it in, and performed Zero Quality Calibration via Xentry. The DPF fill level is rising far too fast! Please could anyone tell me what I could investigate that would cause excess soot?

DPF Changed
DPF pressure sensor & pipes changed
Lambda Sensor Changed
Cylinder 2 Injector Changed
PCV Valve Changed
All Filters changed

All new genuine dealer parts!

 

[M80]

Engine compression, is the PCV passing oil?
Is the turbo passing oil from the seals.

You seem to have eliminated the injectors so is it oil that's clogging the DPF?

 

[LostKiwi]

Have you checked for a boost leak?

 

[supernoodle]

From what I read there isn't evidence of actual excessive soot, just the constant regen?
I note the comment, but no mention of it since

I also noticed that the temp sensor upstream of the Cat. Just after the turbo absolutely shoots up upon acceleration

How quick? Implausibly quick? I'm guessing there is a temp post DPF you can see too? How do they tie up? Obviously there is will be some delay with the post DPF temp coming up, but does it follow?
What happens to the temps when it is doing a regen?

It's just that during a regen I would expect the ECU to be controlling exhaust temp closed loop. If the temperature isn't plausible (in range failure), it could be starting and stopping regen.

What happens if you try a service regen? Does it run or fail?

 

[Aston Dabb]

Engine compression, is the PCV passing oil?
Is the turbo passing oil from the seals.

You seem to have eliminated the injectors so is it oil that's clogging the DPF?

We’ve done a compression test via Xentry and all tests ok. PCV already changed. It doesn’t use a drop of oil. I seem to think this is an overfuelling issue as it is ridiculously poor on fuel even for an OM642 I sometimes struggle to get MPG’s in the 30’s even on a run now!

 

[Aston Dabb]

Have you checked for a boost leak?

We’ve tested from turbo onwards with the MB tool and onwards and found no boost leaks at all from turbo onwards

 

[Aston Dabb]

From what I read there isn't evidence of actual excessive soot, just the constant regen?
I note the comment, but no mention of it since


How quick? Implausibly quick? I'm guessing there is a temp post DPF you can see too? How do they tie up? Obviously there is will be some delay with the post DPF temp coming up, but does it follow?
What happens to the temps when it is doing a regen?

It's just that during a regen I would expect the ECU to be controlling exhaust temp closed loop. If the temperature isn't plausible (in range failure), it could be starting and stopping regen.

What happens if you try a service regen? Does it run or fail?

regen completes Successfully if carried out via Xentry. The fill level increases fast when driving but as soon as the pressure sensor is pulled from the pipes and you drive it the fill level decreases so we assume that it is genuinely filling and it is not an electrical issue

 

[LostKiwi]

Might be time to get injectors checked.

 

[mersum1es]

Yep, a peeing injector means quite often soon hole in the piston... ok, now in half year it would have been happened IMO