Ml270 black smoke

[oigle]

I can also hear the boost/hissing noise at 2000 rpm onwards from the right side where turbo is . I thought turbo comes on at 2500rpm?

Boost actually starts around 1500rpm. Full boost by around 2500.
Hissing noise seems to indicate a boost leak, unless it is from the exhaust side which could be caused by a blocked exhaust. Cats do break up and can block the system. There are 2 cats on the ML.

 

[Adem88]

Hi oigie defiantly coming from the exhaust side. But I feel it has great power, that's why I'm thinking its not a cat

 

[oigle]

Hi oigie defiantly coming from the exhaust side. But I feel it has great power, that's why I'm thinking its not a cat

Should not have pressure on the exhaust side. Needs investigating. Will be causing increased EGT and also reduces overall power because of reduced flow through the engine generally.

 

[Adem88]

Just a thought could it have been chipped or have a box that is making the car run abit rich if so how would I found it

 

[oigle]

Pretty hard to find whether it has been remapped. No obvious signs. Tuning box should be able to be found as it is a separate clip on article near the ecu. Mine is remapped and has no smoke issues at all.
As a guide, do you have a noticeable delay off the mark when you hit the throttle or does it ramp up straight away? Mine had a delay factor - turbo lag - that I considered unacceptable, bordering on dangerous, which is why I had it remapped. It is virtually instantaneous "go" now when I "hit it".
Have you looked at installing the egr delete yet? That would be my first course of action. Cheap easy fix and very beneficial results.
Do check the exhaust for back pressure too as previously said. One thing at a time.....

 

[Adem88]

Hi mate thanks for your reply, I have traced the sound (which sounds like a ****** blow off valve) it is on e left side of the engine bay there are 2 vacuume hoses going into it I think it's called the EGR vacuum transducer and there is a filter at the button of it, the noise is coming from there

 

[oigle]

Hi mate thanks for your reply, I have traced the sound (which sounds like a ****** blow off valve) it is on e left side of the engine bay there are 2 vacuume hoses going into it I think it's called the EGR vacuum transducer and there is a filter at the button of it, the noise is coming from there

That's a long way from the exhaust!!!!!! If the noise is from the transducer, it would indicate a vacuum leak from there. Have you checked the hoses for leaks?
A loss of vacuum there would be stopping the egr from working properly. Once again, an egr delete would take that item out of the equation. Please just do it and then move on if you still have other problems. You seem to be jumping all over the place at the moment.

 

[Adem88]

No problem thanks for your help

 

[Adem88]

I'll get the egr shunt done next week thanks to stump and ill report the results

 

[stumo]

Ok I had a look at this ML today.

General notes:
It chuffs out a lot of black smoke when coming off idle, but once boost is at full it seems to clear out and seems fine, just a touch of continuous grey smoke - but you tend to get that at sustained full throttle I guess.

It has a strange combustion smell at idle, really strong. Its kind of like a leaking injector smell, but the injectors are not leaking at all - did the soapy water check. NB the car has had a bad case of black death at some point in its past, but is cured now, just carrying the tell-tale scars.

The car idles and drives fine and pulls well, it seems to be making and using boost just fine. There were no leaks evident on any of the boosted hoses or intercooler or manifold, everything was surprisingly nice and dry.

So on to the Star diag session:

• There are no relevant codes showing in Star - just glowplug number 2 is out.
• Star compression test passed - all cyls pretty much bang on.
• The injector corrections are all pretty much perfect, nothing greater than 1mg/Hub difference (2 cyls were <1mg positive, and 3 were <1mg negative correction).
• EGR activation test was fine.
• MAF test was fine.
• Barro vs MAP pressure tests were fine.
• Turbo actuation test was fine.

So then I did the EGR shunt mod and unplugged the EGR transducer.

Right away there was a significant reduction in the black smoke coming off idle. There is still what I'd consider too much black smoke though. And the bad idle smell was still there but maybe to a lesser degree.

So at this stage I'm going to say it could be a stuck manifold flap, or a blocked cat. But the car pulls really well, so its kind of inconclusive, and I am leaning more towards the manifold side of things.

So will see how it goes after a bit of EGR-free running. Maybe the EGR valve is still leaking a bit, and so will clog itself gradually and fix the remaining black smoke by itself over time.

I have advised that the manifold flaps should be deleted sooner rather than later, its just a time bomb waiting to happen. I should take my own advice too, but every time I open the bonnet on my ML I get put off by the sheer amount of work involved lol.

 

[oigle]

Ok I had a look at this ML today.

General notes:
It chuffs out a lot of black smoke when coming off idle, but once boost is at full it seems to clear out and seems fine, just a touch of continuous grey smoke - but you tend to get that at sustained full throttle I guess.

It has a strange combustion smell at idle, really strong. Its kind of like a leaking injector smell, but the injectors are not leaking at all - did the soapy water check. NB the car has had a bad case of black death at some point in its past, but is cured now, just carrying the tell-tale scars.

The car idles and drives fine and pulls well, it seems to be making and using boost just fine. There were no leaks evident on any of the boosted hoses or intercooler or manifold, everything was surprisingly nice and dry.

So on to the Star diag session:

• There are no relevant codes showing in Star - just glowplug number 2 is out.
• Star compression test passed - all cyls pretty much bang on.
• The injector corrections are all pretty much perfect, nothing greater than 1mg/Hub difference (2 cyls were <1mg positive, and 3 were <1mg negative correction).
• EGR activation test was fine.
• MAF test was fine.
• Barro vs MAP pressure tests were fine.
• Turbo actuation test was fine.

So then I did the EGR shunt mod and unplugged the EGR transducer.

Right away there was a significant reduction in the black smoke coming off idle. There is still what I'd consider too much black smoke though. And the bad idle smell was still there but maybe to a lesser degree.

So at this stage I'm going to say it could be a stuck manifold flap, or a blocked cat. But the car pulls really well, so its kind of inconclusive, and I am leaning more towards the manifold side of things.

So will see how it goes after a bit of EGR-free running. Maybe the EGR valve is still leaking a bit, and so will clog itself gradually and fix the remaining black smoke by itself over time.

I have advised that the manifold flaps should be deleted sooner rather than later, its just a time bomb waiting to happen. I should take my own advice too, but every time I open the bonnet on my ML I get put off by the sheer amount of work involved lol.

Good one Stumo. As you say, some running with the egr deleted might sort things out. If you are concerned that the flaps are sticking, maybe if the linkage was disconnected and the flaps jammed open, that would prove a point for you.
I too have left my flaps in place. I believe, rightly or wrongly, that with a clean manifold and clean inlet gases without egr abrasives that no further wear should occur on the flaps. A nice oliy clean airflow should keep them good.

 

[cutaresku]

Manifold linkage - is it wide open when pulled to the windshield or viceversa? Cheers!

 

[oigle]

Manifold linkage - is it wide open when pulled to the windshield or viceversa? Cheers!

The default position when idling is "closed". Work it out from there.

 

[Adem88]

Just want to thank stu, he done a great job on my car, the black smoke has gone down to a minimal now, no where near as what it used to be like, I'm sure after a good couple runs it will be gone, car runs alot better and smoother, stu very talented man on the star diagnostics, thanks again pal

 

[Adem88]

Just have to find where the combustion smell is coming from at idle as it stinks

 

[Adem88]

just had another look under the engine bay to find oil coming out of the egr to where it connects to the manifold, when i removed the egr to clean it i must not have put i back on right and the bolt at the buttom is only half way in which is not giving a proper seal, well i hope this is the answer to my problems, the egr shunt did minimise the black smoke but was still there so hopefully once i tighten all bots from the egr all should be ok

 

[stumo]

I reckon once that leak is sealed it will 100% fix your remaining black smoke and odd smell problem.

I'm not sure why that leak didn't show up the other day. I was specifically looking for that kind of telltale oil seep to show us where the leak was.

Maybe the soot from the EGR was absorbing the oil in that area? Its right where the EG enters the intake. So maybe the oil was being carried into the manifold/engine by the soot, rather than collecting and seeping out that leak.

That leak must have been there on Monday, but the oil seeping certainly wasn't.

Anyway, at least its been found now.

 

[Adem88]

hey stu i think that combustion smell is coming from the oil seperator pipe which has a hole in it, will be replaced this week, i took the egr back off cleaned it and made sure everything was tight, well took it for a test and the smoke is still present no where near as what it used to be but still is, i had a car behind me at the lights tonights and i accelerated quite hard and seen allitle bit of smoke but as i said no where near as what it used to be

 

[oigle]

hey stu i think that combustion smell is coming from the oil seperator pipe which has a hole in it, will be replaced this week, i took the egr back off cleaned it and made sure everything was tight, well took it for a test and the smoke is still present no where near as what it used to be but still is, i had a car behind me at the lights tonights and i accelerated quite hard and seen allitle bit of smoke but as i said no where near as what it used to be

You will never get to the situation where there is NO smoke when accelerating hard. Following lights will always show some.
Think you are probably right about smell coming from your split PCV hose.

 

[Adem88]

Hey mate well it pretty much sums it all up then no more big puffs of black smoke during the day , car runs a lot better and smother thanks for everyone's help