D40 Loss of Power and Black Smoke

[Quadfractum]

Alright, so my 2.5L 2006 Spanish D40 with 250K ish km's on the clock has all of a sudden had massive power loss at low revs. It seems when the boost hits its peak, (4k in first, about 2.5k in the rest of the gears) it will accelerate and leave behind huge clouds of black smoke. (Usually, more than in the attached video) The symptoms came on very quickly, parked for 2 hours, and came back to these problems. OBD2 reader had no codes at all and no lights on the dash.

It doesn't seem to matter if the engine is hot or cold, (although air temps are a bit cooler, doubt it matters). I've tried cleaning the MAFS to no avail, I also just unplugged it, which seemed to kill the boost I get when I hit 2.5k revs, but it ran no worse than it did before. I've got a spare D40 which I will swap the MAFS with tomorrow to see if that helps too.

I also had a look in I think it was the EGR valve, that looked all good. The SCV was also replaced not too long ago, along with the fuel filter. I recently also filled up with regular diesel instead of the premium diesel I usually use, but that's probably just a weird coincidence. I took it for a quick test drive at the end of the day and the intercooler hose attached to the engine blew off.

I've probably forgotten to write a few things so please ask away, any help will be greatly appreciated!! Thank you in advance.

 

[Old.Tony]

A look inside the EGR valve may not indicate whether or not the valve is functioning correctly. A blanking plate in where the gasket goes where the gold tube meets the EGR valve is the most effective way of determining if the EGR is causing any issues.

Black smoke like you're describing (I can't see the video for some reason, I can only hear it) can be caused by:

* Turbocharger failing. Unlikely in this case because you've noted that it still has the power to pop the intake hose off.
* Turbocharger control failing. Possible - the Boost Control Solenoid may be getting "sticky" (I don't know if that can be fixed) or one of the vac hoses may have an intermittent leak (more likely on a join where the end of the hose has hardened). Vacuum loss is sometimes accompanied by a reduction in braking performance - if you have to press your brake harder now to stop at the same rate that you used to, then vac hoses are your likely culprit.
* EGR valve fault. It might just be sooted up, or it could be a fault in the valve. Either way, that blanking plate will point straight at this if it's the problem child. Your choice then is to either keep the blanking plate in place, or replace the EGR valve.
* Exhaust hole. Most often in the EGR tube just out from the exhaust manifold connection, a leak here will not allow the turbo to get to full boost early (it's supposed to reach full boost at 1800rpm). This is also dangerous for the occupants and for the engine bay especially when the engine is working harder (more flames in engine bay = more danger).
* Injector issues. Usually varnish, can sometimes be cleaned up with Liqui Moly Fuel System Treatment and about 200kmm of driving, or half an hour with a Liqui Moly Diesel Purge. Failing that (if the injectors are suspect) they can be removed and cleaned but this MUST be done carefully as it's a common rail engine - the injectors receive fuel at enormous pressures (YD25 up to 24,000PSI and V9X up to 26,000psi).

Cleaning the MAFS could help, as could cleaning the intercooler (petrol is a good solvent for the gunk inside). Checking for boost leaks is also a good idea, the black oily emissions are not that hard to find.

Let us know how you go!

 

[Quadfractum]

A look inside the EGR valve may not indicate whether or not the valve is functioning correctly. A blanking plate in where the gasket goes where the gold tube meets the EGR valve is the most effective way of determining if the EGR is causing any issues.

Black smoke like you're describing (I can't see the video for some reason, I can only hear it) can be caused by:

* Turbocharger failing. Unlikely in this case because you've noted that it still has the power to pop the intake hose off.
* Turbocharger control failing. Possible - the Boost Control Solenoid may be getting "sticky" (I don't know if that can be fixed) or one of the vac hoses may have an intermittent leak (more likely on a join where the end of the hose has hardened). Vacuum loss is sometimes accompanied by a reduction in braking performance - if you have to press your brake harder now to stop at the same rate that you used to, then vac hoses are your likely culprit.
* EGR valve fault. It might just be sooted up, or it could be a fault in the valve. Either way, that blanking plate will point straight at this if it's the problem child. Your choice then is to either keep the blanking plate in place, or replace the EGR valve.
* Exhaust hole. Most often in the EGR tube just out from the exhaust manifold connection, a leak here will not allow the turbo to get to full boost early (it's supposed to reach full boost at 1800rpm). This is also dangerous for the occupants and for the engine bay especially when the engine is working harder (more flames in engine bay = more danger).
* Injector issues. Usually varnish, can sometimes be cleaned up with Liqui Moly Fuel System Treatment and about 200kmm of driving, or half an hour with a Liqui Moly Diesel Purge. Failing that (if the injectors are suspect) they can be removed and cleaned but this MUST be done carefully as it's a common rail engine - the injectors receive fuel at enormous pressures (YD25 up to 24,000PSI and V9X up to 26,000psi).

Cleaning the MAFS could help, as could cleaning the intercooler (petrol is a good solvent for the gunk inside). Checking for boost leaks is also a good idea, the black oily emissions are not that hard to find.

Let us know how you go!

Hey Tony, sorry for taking so long to reply, it was in the shed for a while and then I forgot about this post. In the end it was a faulty egr valve. The first mechanic that I took it to claimed the stretched timing chain was the issue (it was pretty slack). I decided to tackle the job myself which saved me a couple grand, thanks to yd25.com, but when that didn't fix anything I got fed up and gave it to ultratune who fixed it by the next day. I guess I know what to look for with a broken egr valve now. Oh well, upgrading the timing chain can't hurt I suppose, and thanks for your help.