Does Black Smoke mean a DPF is Shot (Blocked)?

[m80]

I have a puff of black smoke when I blip the throttle at standstill. So an MOT failure.

It has been regenerating every 430 / 460 miles.
It has low soot content but possibly high(ish) ash content.

It has been suggested that there is a path through the DPF, but the regular regeneration would contradict that, wouldn't it?

If the DPF is now partially blocked , with ash, wouldn't that prevent gasses generally, and also prevent black smoke?

 

[Teego]

Are you using the correct low-ash oil?
Have you tried giving it an Italian tune-up?

 

[m80]

Yep,
correct oil,
good runs with power.

 

[Phil1968]

Has it been re-mapped? Air leak on the induction side?

 

[m80]

I'm not aware of a remap,and I see no evidence.
Power is ok, EGR still operates.

I'm thinking of a leak on the intake side also.
New injectors, all recalibrated on Star.

Can smoke pass a healthy(ish) DPF?
Is a little smoke to be expected?
Would a new DPF stop the smoke and permit an MOT pass?

I can monitor for soot and ash levels later.

 

[Bellow]

Swirl flaps present and correct?

 

[m80]

Yes, all in order, inlet manifold cleaned.
All moving correctly.
Inlet manifold, inlet riser all looked in good order at strip down.

Recently replaced the 4 'o' ring seals in the 2 boost pipes.
Integrity of the intercooler checked good at strip down.

EGR cleaned also.

Valve seals replaced,
valves lapped.
Compression within 2 revs of each other (11 allowed).

New injectors fitted,
zero values reset at tick over, and calibrated.
Running values reset

 

[Bellow]

It has been suggested that there is a path through the DPF, but the regular regeneration would contradict that, wouldn't it?

If the DPF is now partially blocked , with ash, wouldn't that prevent gasses generally, and also prevent black smoke?

Irrespective of anything else, that's a conundrum.
My understanding is that the DPF blocks all soot (merely needing re-gen sooner as the internal accumulation chokes it).
My understanding is that the re-gens are occasioned by a pressure differential which would not occur if there was hole in the filtering medium (through which soot could pass). Which is in line with your thinking but doesn't answer what the hell is happening.

 

[m80]

I've been out to it again.

I'm not sure what to expect,
but the boost controller (pretty sure that means turbo actuator) doesn't look to perform a full range 'actuation' when tested.

The test ranges from 10% to 90%.
Mine rises to about 20%+ (and increases revs to about 1,450) and after a while drops to 5% (and revs to tickover).

I can see how a reluctant turbo actuator might starve of the 'oxygen' when revving.

Any thoughts?

 

[BlackC55]

What car is it? or engine?

 

[m80]

2014 Viano.
OM651.940, single turbo.

I took the turbo actuator off, even though it can manually be manipulated through full range easily.
I would have some one cycle the ignition while I watch but I'll have to wait for Mrs me to get home for that.

Anyway, striped it's clean inside.
I applied 5 volts to the motor within and it travelled full range with ease. It may be it should do it v fast but it seemed fast enough to me.

Fwiw, it'll kick down and pull while on the road.
No codes.

 

[BlackC55]

Take off the DPF off and have a look at it. Some blow holes through the middle of them.... If they are faulty they do tend to bring on a code though.

 

[Supernoodle]

Normal non scientific test is to rub your finger around the inside of the tail pipe. If it comes out covered in soot, the DPF is cracked.

 

[BlackC55]

I'd do a smoke test firstly. Pay close attention to the inlet manifold. The leak can be tiny. If you have no codes the system knows no fault then I would suspect the DPF has been removed possibly. Its difficult to say but its worth a look inside it. 651 engines with a DPF do not often smoke. Is the smoke black, grey, or blue? Is it smokey under load or just when revved at standstill?

 

[m80]

It passed the MOT on Thursday, with emissions of 0.01
This has been one hell of a saga.
I replaced the DPF, after a new turbo cartridge last week.

It has had new injectors,
head off and new valve seals, valves lapped.
EGR and inlet cleaned and checked, not really dirty anyway.
New seals to the boost pipes.
New engine and gearbox mounts while the engine was out.

All because of an emissions failure at 0.39

Yesterday I ran it 230 odd miles. Some what buzzy and not as powerful as I remembered.
It has been off the road since late January.

Anyway I ran the fuel down to fumes. With fresh fuel it felt improved for the last 15 miles.
I had added 2-EHN during last December, in hope it would clean the system. Possibly I had been over generous with my additive, and then it stood for months.

I think I've done my bit to save the planet.