DPF Differential Sensor 'Implausible'.

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M80

M80

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Was the starting still lumpy,,?
It still is reluctant to start. When started is lumpy, but smooths out after it warms a little, but can become lumpy again.

Splitting the exhaust at the pre cat joint made no difference. Of course codes needed resetting after that.

There were some strange bump type noises earlier in the week post shutting down or post attempted start. For elimination I've dropped the fuel tank. Now I'm trying to open it up at the lift pump ring. Tight as 'eck.

I still favour this being the re conn'ed injector/s, but that guy is too busy to answer the phone.
 
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An update.

It performed a forced regen yesterday.
Over approx 5 miles the fill level dropped from 124% down to 82%. Then started to fill slowly again, up to about 85% after a further 15 miles.
That would equate to around 500 miles between regens, so good.

I attempted another forced regen and while iCarsoft informed me that it was in 'test', but the exhaust temps didn't rise, so no regen.

My fuel rail rail pressures are about
3.9 bar with ignition on but static.
42 bar (ish) while cranking.
310 bar at tick over, that'll rise significantly while revving.

From what I've read the cranking pressure looks low, but I don't know what the threshold for starting should be.

iCarsoft won't interrogate the 639 injectors in any fashion, the facility is just not present. On the 211 there is lots more information available.

I still suspect the reconditioned injectors, these are Delphi solenoid type.
I can imagine that the low cranking pressure 'may' be down to excessive leak off, and that may hold off the start until the pressure reaches the threshold.

As usual thoughts appreciated.
 

supernoodle

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An update.

It performed a forced regen yesterday.
Over approx 5 miles the fill level dropped from 124% down to 82%. Then started to fill slowly again, up to about 85% after a further 15 miles.
That would equate to around 500 miles between regens, so good.

I attempted another forced regen and while iCarsoft informed me that it was in 'test', but the exhaust temps didn't rise, so no regen.

My fuel rail rail pressures are about
3.9 bar with ignition on but static.
42 bar (ish) while cranking.
310 bar at tick over, that'll rise significantly while revving.

From what I've read the cranking pressure looks low, but I don't know what the threshold for starting should be.

iCarsoft won't interrogate the 639 injectors in any fashion, the facility is just not present. On the 211 there is lots more information available.

I still suspect the reconditioned injectors, these are Delphi solenoid type.
I can imagine that the low cranking pressure 'may' be down to excessive leak off, and that may hold off the start until the pressure reaches the threshold.

As usual thoughts appreciated.
Common rail injectors usually need at least 150 bar for guaranteed injection, but the min pressure for closed loop operation on the old delphi systems was something like 230 bar. Newer systems are typically 250 bar min.
During crank I expect 230-250 bar, then during the run up 400bar, then down to 230-300bar for idle. The newer the car, generally the higher the pressures used.
I've not got a diag tool for the Merc but usually there is a PID where you can see the rail pressure setpoint.
The best way of looking at the rail pressure is an oscilloscope on the pressure sensor. You can get real good scopes for under £100. Useful for nosing around and testing on the car. If you look at the rail pressure signal on a scope you can see the pressure pulses from the pump and the drops due to injection. Even if you can't convert the volts to bars, the shape tells you a lot.
 
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alexanderfoti

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Sorry been meaning to chip in on this:

651 engines love to get air locks at the back, they usually have extended crank after breaking into the fuel system for a while. IF you drive it 20-30 miles and it still has a long crank then I would suspect one of your reman injectors (I only fit MB Reman on these engines as I have no luck with aftermarket stuff).

As you also have visible smoke, I would say one of the injectors is no good. There is a bleed procedure on STAR that would get rid of some trapped air around the hp pump area, but I find this usually clears on its own.
 

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Had the black smoke on my wifes old 2014 1.5tdci fiesta, 2 of the new injectors i bought were faulty and they were rebuilt locally, took them back got 2 new ones put the new numbers in and clean as a whistle, it was also hard to start.
 
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Thanks again.
I guess I've driven 60 miles or so, still slow start, but possibly some times easier.
W/o the MIL It still has the returning DPF low cct fault. It is down on mid range power, and doesn't rev hi.

These are my original injectors with new nozzles. I now wish I had bought new Delphi from P Jones.

After my driving and high fuel pressures 'I' would be surprised if air was still in there, but I'm inexperienced.

iCarsoft V2 is lacking for the 639 so tonight I've ordered a Star set up so I can interrogate this properly, I might well be requesting some guidance on that later. I can try the bleed procedure before writing off an injector (or 2).

Work stuff is now backed up and while the 211 doesn't have the same advantages it has been bailing me out over the last couple of days. It feels happy to just get on with it.
 

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In that case just fit some proper reman injectors and that will sort it.
 
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Update,
Saturday was spent interrogating with my new diagnostics. In truth familiarising myself with the programme.

Sunday reconditioned injectors out, new Delphi injectors in.
Started after a laboured crank, exhaust smoke. Tried 2 more starts and it was reluctant.
Deflated, the family turned up and wanted to go to the Guinness shop. I was ready for some of that so packed up.

This morning a reluctant start, but easier. Took it for a run and it had improved much.
I've entered the new 20 digit codes for the injectors,
reset adaptation / quantities,
I wouldn't say it's ideal but certainly acceptable. Am I right in thinking it now needs to complete a teach in process while driving?

I'll be asking those with experience if my opinion on the reconditioned injectors is correct, before challenging the 'specialist' who is clearly keen to blame the Viano, or the fuel, or me of course.
 

alexanderfoti

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As before, you have broken into the high pressure system, so after the first start it will reluctant to start until driven or the bleeding procedure is carried out. That should then settle down.

The smoke should also settle down once, driven.

When you say its much better with the new injectors, but not ideal, in what way? Combustion noise? Jerkyness? smoke?
 
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Not ideal in that it isn't an instant start,
there is some evidence of exhaust smoke. when throttle blipping, stationary.

It seems like you are of the opinion I will see improvement after a reasonable run.
I haven't been on the road since resetting values.
 
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I've to admit to being easily confused, but maybe I can be enlightened.

Starts easily, some evidence of whiteish smoke as I pulled out of our road earlier, then no evidence.

Up to temperature and used iCarsoft to perform 2 regens, 1st brought fill level from 120% to 43%, nice. 2nd down to 11% or less.

The Mil is up again, after resets. Still for DPF. The DP is either open or short to earth.
My confusion, I would have thought the DP sensor would be reporting the fill level but iCarsoft and my better diagnostics says faulty. Even stationary the 'better' is reporting the fault.

I've replaced the DP sensor for the new. The old I've bench tested and looks good. 5v across 2&3, blow in each tube and the output on term 1 will rise or fall.

Exhaust back pressure reports as good.
Ash level did report as 9.8, where 9 is max. I didn't interrogate that today.

Good power low end,. Doesn't rev or kick down so restricted power higher up.

I have assumed a poor connection at DP or even ECU. I intend to confirm when the deluge stops.
But if the soot level reports (what seems) appropriately how can the DP be showing as faulty?
 

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I expect your seeing a modelled soot value, ie not from the DP. I admit I expect a regen would not be permitted if DP had an error though.

An open circuit or short to ground are treated the same as internally the ECU will have the sense pin pulled down to ground via a high value resistor.
It's a simple electrical diagnostic, it's suggesting ECU is measuring ~0v on the sense pin.
An analogue sensor usually will output a voltage in the range 0.5v to 4.5v. If ECU sees below 0.1v or above 4.9v it knows there is a short (remember an open circuit behaves like a short to ground) . If there's a voltage in the ranges 0.1 to 0.5 or 4.5 to 4.9v it might give the implausible error. (note the actual numbers will vary, but they'll be of that order).
Some piercing probes can be handy to test with here.
 
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Yes the, I think it called it raw value, was measuring 0.00, now post regens it is 0.02 (from memory). Anyway outside of permissible parameters, so implausible.

I think you are saying that the ash figure is more a calculation, or an MB assumed condition, rather than a sensor measure??

I can understand how the implausible value would trigger the Mil, and even cause limp, as I'm experiencing. But soot value seems to be measured with some accuracy.
To me that is a contradiction.

I can replace the DPF, but this seems to be another crossed fingers attempt.
 
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I now accept that the DP sensor was implausible.
All 3 wires had continuity, but the return continuity was down to 12 ohms.
Considering the return voltage is circa 0.5 volts that'll do it.

Not easy to see but the part of the loom feeding the sensor had, I guess, been resting on the exhaust at some point.
Stripping back the insulation and the wires had melted together, but not shorted. With my manipulation of engine out / in, and tracing the siring for future reference I must have caused the copper cores to separate.

A new patch soldered in,
all teach in resets completed,
and it's going well, sort of.

With the turbo feed off I could see oil has been passing the turbo. That is probably my cause of smoke, via the PVC.

I might as well marry this bl88dy thing for the attention it demands.
 

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mmmm what year is your vito?, when i had my 2013 vito the mil lit after about 2 weeks of buying it, so i took it back to the dealer, apparently the wireing for the dpf pressure sensor needed replacement and mercedes replaced it under warranty. just a thought
 
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2014 Viano,
I've patched in a section.
 

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Glad you made some progress M80.

When I mentioned modelled soot, it's not some simple look up table. It's a complex function that uses many temperatures, pressures, flow rates etc to constantly estimate soot produced and soot load in the dpf.

The main soot estimator uses the differential pressure sensor, but if like you did, get a fault you need the back up.
 
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Update,
I disconnected at the PCV, plugged the feed to the inlet and with a pipe pushed on left the PCV open to atmosphere. Over 60 - 70 miles it was bone dry. Better than expected.

Turbo cartridge replaced and the white smoke pretty much stopped.
New DPF and adapted and the black puffs of smoke look to be eliminated. Alexander wins the virtual prize there, thanks.

I feel it's ready for the MOT, but let's see what they say.
Then I'll monitor for soot and ash build up.
 
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The 14th October shall be a day of celebration going forward, well the evening anyway.
It passed with 0.o1 emission whatevers.

I'm feeling good.
I can now look back at the sage much more positively.
Was it all worth it, was it 'ellers like.
It's been ****** ridiculous.
 
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