'05 C220 Black Smoke and Powerless

[JSeaman]

Not wanting to get drawn into a slanging match but I've asked for ideas and seen a spat about redex and a comment saying I'm clutching at straws. So far I've done the EGR and induction pipes which I stated I would check in the first post. So essentially no, I haven't got any further along due to any input here. I am, however, really hoping someone has something valuable to contribute i.e. ideas.

This was a private sale so no dealer involvement.

I used some Merc specific tools (WIS etc) in the past and they were an advanced version of OBD but they still had the same underlying error codes as the OBD interface. Is there something specific any of you have in mind that wouldn't show up on OBD but could cause this?

 

[LostKiwi]

Its also unlikely to be turbo seals. Turbo seals give blue smoke not black.
Also the inlet tract is where the engine breather is connected to its common for oil to be present. I would check the turbo by all means but I seriously doubt the seals are your issue.

 

[LostKiwi]

I used some Merc specific tools (WIS etc) in the past and they were an advanced version of OBD but they still had the same underlying error codes as the OBD interface. Is there something specific any of you have in mind that wouldn't show up on OBD but could cause this?

The underlying error codes are often similar but the STAR codes will sometimes have secondary values (for example a 2 digit code after the normal 4 digit one) that give further information. The main benefit of STAR though is in the live data and guided diagnosis and the way it flags values that are out of spec. It gives a far more detailed view of what is going on than any third party generic reader.

 

[JSeaman]

Thanks for that, with no OBDII being stored at all I figured real time sensor diagnostics would be the proposed benefit

Agreed the turbo seals will blow blue oil smoke, just another thing to add to the 'to do' list

Any thoughts on what it could be?

 

[Steve@Avantgarde]

Well STAR in the hands of a good tech is an invaluable tool and in no way an OBD code reader.

For example you have a running issue, you can monitor every actual value the engine needs to make it run to spec. It shows the spec value and what the engine is actually running at. That can lead you straight to the fault. You can actuate components to see if they are working properly and simulate tests on them to see if they are performing in action. If the car has a fault code, it will give you a specific guided test programme so you eliminate or condemn components. Along with that it might ask you to measure charge pressure or smoke test systems to check for leaks (essentially the only way you can guarantee a sealed inlet system).

I wasn't trying to initiate a slanging match, but help you to save money and time! There are so many possibly faults that could cause your issue and you will eventually get there if you go down the route of throwing time and parts at it. But 45 mins max on a STAR machine and you will likely have the issue sorted or know what you need to do to fix it.

Like I put on the Redex thread, I've never seen additive fix a running fault. But I have fixed a good few faults by using STAR and diagnosing engines properly.

 

[JSeaman]

Thanks, that's a useful post. I share your view on the additives fwiw.

I'm certinly not throwing parts at it, so far I've bought a stat (which it needs). I'll poke about a little further and if I find nothing else I'll look further at finding a STAR guy

 

[turbopete]

just whilst you are having a visual look around for anything obvious, the ends of the intercoolers can be a source of leaks (where the plastic ends crimp onto the alloy 'core' area) as I found with mine. both the original and a sub standard replacement (replaced under warranty) failed at the ends.

 

[JSeaman]

Thanks for that, I'll have a good poke around there

Went to change the stat tonight and found I have the wrong one, I have to extra connections (big holes!) on the new one

 

[JSeaman]

New stat fitted and things are better, also did an oil change and fixed a broken wire in the indicator as well as a coolant swap. Found a PCV pipe not well seated and the turbo inlet hose clip loose but I'm still left with smoke only at heavy throttle though. Intercooler pipwork looks OK but I'm going to take it off completely and have a look at that when it warms up a bit!

 

[JSeaman]

STAR diagnostic showed no error codes and sensor test showed everything was in spec except airflow which was supposed to be around 400 at idle and was hovering ~5 below so near as dammit in spec. Ordered a new sensor and no different so I'm changing the IC next. Any other ideas?

 

[Westheath]

The Star technician should have gone through a guided test procedure for the complaint and not just a scan.

Have you had a smoke test done for leaks in the charge pressure system ?

 

[JSeaman]

No smoke test but that indicates you are thinking the same as me, induction pipework leak?

 

[oigle]

Usually the first thing to look for with black smoke, or stuck EGR.

Ian.

 

[JSeaman]

Thanks Ian, checked the EGR already and suspected an induction leak, will switch the IC and go from there

 

[Frontstep]

Sounds very much like an egr issue I had with mine which also went through a full star session and smoke test, star is good but not infallible and of course it depends on the person using it being competent.

 

[JSeaman]

EGR seems to be moving freely, not coked up and not throwing any codes but agree with you

 

[fifthwheel]

I had a W203 with just the same symptoms it had a knackered turbo. It had been badly serviced the oil feed to the turbo was blocked.

 

[Frontstep]

EGR seems to be moving freely, not coked up and not throwing any codes but agree with you

Mine did.

 

[JSeaman]

Thanks both, I figured turbo should smoke all the time though, possibly wastegate leaking may show up under higher boost?

Any thoughts on verifying the EGR short of buying one?

 

[oigle]

The egr piston can develop chatter marks on the sides and this can jam the thing slightly open. Hard to see. Doesn't take much to allow exhaust gas under pressure to infiltrate when it isn't supposed to. This depletes the oxygen level and thus fuel is not fully burnt.
Have you considered electronically deleting the egr operation? Quite inexpensive compared to buying a new unit and also saves the inlet manifold getting all coked up again (if you clean it out) I think your motor has the vacuum operated EGR system and is very easily modified.

Ian.