Technical Fiat Ducato x250 black smoke limp mode

[MotherTrucker]

Hi everyone, I'm new here, I bought my first Fiat Ducato motorhome (2011 Multijet 2.3) a little while ago and now I'm having trouble sorting out an issue with it as it failed the emissions on its MOT. It belches out black smoke on revving up and it wont rev over 2750 so it seems its in limp mode. This forum has been really helpful and having read a lot of posts about this I've tried the following so far:

OIl change
Checked fuel cap seals properly
Redex
New air filter and fuel filter (no mice in there!)
Checked OBD for codes, there are none
Looked for DPF, cant see one so I assume its Euro 4
Removed and cleaned MAF sensor
Checked inlet pipes for blockage
Removed the vaccum solonoid for the EGR and tested, its seized, new one on order
Removed throttle and cleaned it up (it was quite clean anyway, also descovered an EGR blanking plate there)
Replaced MAP sensor (as I mullered it whilst removing it to clean it)
Checked intercooler and hoses, they all seem ok
Gone in with WD40 all round the electrical connectors in the engine bay


I'm now worried it might be the turbo, I was planning on checking everything then trying an italian tune up but want to make sure I'm not doing more harm than good if its overfuelling. Has anyone got any other ideas?

Oh, and from the service book all 4 injectors were replaced recently so I figure its less likely to be them?

I'm hoping someone here might give me some pointers as Im feeling a bit at a loss now, I love a bit of mechanics but feel defeated now! I've gone from thinking its air intake to EGR to intercooler etc etc and nothing seems to make a difference. I've ordered the MultiECUScan software, just waiting for it to turn up.

Thanks in advance

 

[bugsymike]

Garages do a "smoke test" to show up any leaks on the inlet side.
A simple test might be, if possible to remove the rubber pipe from the turbo just before the inlet manifold and get someone to rev it up and see if you can hold it blocked with your hand and a cloth maybe. If turbo working well and no leaks, it should be nearly impossible to hold it blanked off as 20psi plus pressure.
In simple terms black smoke in a diesel is too much fuel or not enough oxygen. The fuel side is more sensors and ECU control, so the MES code reading will be more help there.
Note keep well away from the inlet side as the engine vacuum will be strong !!! Also don't let anything suck into open inlet manifold, rags, small children etc.

 

[MotherTrucker]

Hi bugsymike, thanks for your reply. Oo thats a good idea I shall try that, I did try quickly blocking the intake with my hand (at tickover) to see if I got any sucking from the intercooler hoses, the left hand hose which connects to the throttle body collapsed, does this give a clue? I dont have a second pair of hands atm to help rev it up so I shall have to test the turbo pressure later.

Also. the plot thickens today, last night I thought I'd just sanity check the MAF and unplugged it and the smoke stopped, so off I went this morning to buy a new MAF thinking I'd solved it, fitted it, but still the same problem! Damn it. So I gues thats telling me it is an overfuelling problem, as when I unplug the MAF and ECU sets the injection to defaults I think when you unplug it? The smoke disappears but limp mode remains. But its not the actual MAF thats the problem as a new one doesnt fix the smoke or the limp mode, still no codes from my cheapy OBD reader and no effect when I run the clear codes command on it.

I'm guessing other sensors could be the problem now, but the MAP has already been replaced... are there any more for air intake?

 

[MotherTrucker]

..it was a proper Bosch MAF btw, so is the new MAP sensor.

 

[bugsymike]

..it was a proper Bosch MAF btw, so is the new MAP sensor.

It was more the pressure side than the suction side, poor boost= not enough oxygen for the fuel =black smoke.
Only a possible cause , but cheap to check and no parts involved.

 

[MotherTrucker]

I see what you mean yeah good point. Could it still be a boost problem even though default mode cures it do you think?

 

[MotherTrucker]

The other thing to note, is just before this issue I had to replace the fuel filter housing as it spewed diesel everywhere, I'm wondering if its to do with that. Anyone know what the plug on the bottom of the housing does?

 

[bugsymike]

The other thing to note, is just before this issue I had to replace the fuel filter housing as it spewed diesel everywhere, I'm wondering if its to do with that. Anyone know what the plug on the bottom of the housing does?

I think you will find that is a water sensor, to show a light if water in fuel.

 

[MotherTrucker]

Ah good to know, thanks.

So my MultiECUScan sofware turned up today Having connected up it looks like a wiring problem, I'm getting P0104 MAF sensor high fault, I've tried both plugging in the new MAF and clearing the faults but it comes back, and more interestingly if I leave it unplugged all together I still get the persistant error. Looks like could be a short maybe?

I had a look at my boost pressure too, its going up to around 26psi when revving a bit, does that sound ok? There are no other codes coming up

I'm now hunting around for wiring diagrams anyone know where I can find one? I cant seem to find a Haynes manual anywhere either.

 

[bugsymike]

Ah good to know, thanks.

So my MultiECUScan sofware turned up today Having connected up it looks like a wiring problem, I'm getting P0104 MAF sensor high fault, I've tried both plugging in the new MAF and clearing the faults but it comes back, and more interestingly if I leave it unplugged all together I still get the persistant error. Looks like could be a short maybe?

I had a look at my boost pressure too, its going up to around 26psi when revving a bit, does that sound ok? There are no other codes coming up

I'm now hunting around for wiring diagrams anyone know where I can find one? I cant seem to find a Haynes manual anywhere either.

I have a Doblo which had a P010F code relating to the MAF sensor correlation etc. and the fault was the leak on the EGF cooler pipe air leak at the inlet manifold, it was chucking out lots of black smoke, but a gasket and new bolts cured it without a new MAF sensor.
The point I am making is the diagnostics give an error code but it doesn't necessarily mean that sensor , just something affecting the readings from that sensor.
pwerhaps the MES side of Forum can advise most likely cause.
Re Haynes, these days they don't seem to be much help, their answer to anything different seems to say go to dealer!

 

[MotherTrucker]

Fixed it!

So having loaded up MES I found the 'reset MAF' or something like that, I ran it and the P0104 error went away. I didnt realise you had to reset the ECU so was pure luck I found it trawling around MES. Its not even a new MAF, I just cleaned it.

Went for its MOT retest and passed, so happy. The emmisions went from 3.5 to 0.2 which Im really chuffed with.

Thanks for all your help!