W203 270 CDI smoke and limp mode riddle

Zaverho

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Hi,

I have a Mercedes C class, 2005, 270 CDI with 390.000 km. I know, a lot. But I love the car and the interior is gorgeous :)

The problem:
When accelerating there is a lot of black smoke comming out of the exhaust. Even a fast rev in park would create a cloud of smoke. Sometimes the check engine light turn on and it goes in limp mode. There is a fair amount of power when not in limp mode. Shifts fine. A lot of oil in boost pipes and EGR.

The work allready done:
-Head renewed, with seals, polished valves and whatnot.
-New original intake manifold and flap motor (last thing I did - at the stealership - the test showed low boost pressure and leaking sistem. No change in smoke situation)
-New EGR valve (when I bought the car the EGR was disconected as it was not working)
-Injectors check and set, new seals
-New filters, plastic fuel hoses
-All 3 boost pipes checked for cracks
-All rubber vacuum hoses replaced
-MAF cleaned and engine tested with a known good unit with no difference

Signs that might help solving the riddle:
-oil is collecting around oil cap
-connector at vacuum pump is broken but stays on
-I havent yet tested the compression

Suspects at the moment:
-Turbo actuator
-Turbo


Where should I go next? Any ideas would be more than welcome...
 
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Zaverho

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W203 270 CDI 2005, W124 300TE 1991, W114 230.6 1971
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The last time I scanned I just got (at the dealership, I'm reading the printout)
P1664-002 Elektrischer Zuheizer Geratefehler
P1192-001 B40 Oil sensor faulty (since changed)

Before I got the code I don't remember anymore, but it was connected to boost pressure.
 

alexanderfoti

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What colour is the smoke?
 

alexanderfoti

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He said, black.

Long day!

Run a boost test and see if its meeting target, if not, carry out boost leak test, if system is leak tight, then low boost = low air = more black smoke.
 

LostKiwi

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I'd be having a very close look at the intercooler.
 

abazem

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Happened to me once and it was giving an error code of low boost or something and the car was going into limp mode with CEL. Turned out to be blocked cat once decat it is working fine.
 

bembo449

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black smoke on a derv is usually a boost leak in my experience so as others have suggested , get the intercooler and associated pipework checked , it doesn't take much of a leak for it to cause this problem
 

ajlsl600

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dont spend anything except yr time till yr certain no boost leak, pay attn for whistling sound . coming in from about half load.
 

Steve@Avantgarde

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It will either have a split turbo hose from the intercooler (usually the one to the manifold) or a leak of the intercooler itself.

If you can find someone to do a smoke test, you will find the leak.
 
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Zaverho

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So I brought the car to a local MB specialist, he checked boost pressure, compression, MAF, Cats (front), Cats (back - it is impossible to check visually, but he tested with air an water), all vacuum valves, EGR... Everything ok.

We ended up replacing the injectors, but it did not solve the problem completely. After 1000 km of hard driving there are no error codes on Star.

It still puffs a cloud of smoke at the very beginning of the acceleration, even before the revs go up.

Hell, I might just drive it like this. But I guess I'll never gonna be totaly relaxed :D
 

oigle

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Sounds like you have fixed 99% of the issues you had. A decent puff of black when tramping the throttle is not unusual for a diesel so long as the smoke is only for short duration. Should fade to a haze as the speed and revs build up.
You don't say if you had the car from new. Perhaps someone has changed the mapping for better throttle response off the mark. I've done that to mine and it creates a puff of black when the throttle is hit at all hard. Fixed the flat spot off the mark though which is what I wanted.

Ian.
 
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Zaverho

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Thanks Ian for that input. I just had it for two years now and I woulnd't be surprised to find that it was remaped. I have no experience with remaping whatsoever: can it be reversed? Are there remaping specialists and can they tell if it was remaped?
 

alexanderfoti

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Thanks Ian for that input. I just had it for two years now and I woulnd't be surprised to find that it was remaped. I have no experience with remaping whatsoever: can it be reversed? Are there remaping specialists and can they tell if it was remaped?

As above, a small puff of smoke before the turbo comes on is normal and nothing I would be too worried about.

Yes there are and yes we can. Any indy that can do software updates will be able to revert it to standard.
 

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