Black Smoke

[grantracy]

Just got my coach back after having some work performed including engine service(replace oil/fuel filters change engine oil)on my series 60. When starting out from a stop it is blowing a good quantity of black smoke that slowly dissipates as the rpm come in. Boost seems normal....any thoughts ?

[Jon Wehrenberg]

Black smoke is usually an indication of unburnt fuel from excessive amounts relative to available air. If boost is normal the presumption is the engine is getting enough air. The boost is a good way to verify turbo operation and rule out leaks in the air to air intercooler.

If it were happening to mine I would pull the inlet to the turbo and just make sure the turbo spins freely. Assuming that is OK I would see if there are any codes. I was of the opinion that our vintage DDEC controls fuel flow based on turbo boost so we do not get the sooting on start from idle which is why I would look at codes. Any check engine lights?

[grantracy]

No check engine lights...haven't road tested but in neutral without a load can get 15 from turbo..will report when I get on
The road to Daytona

[AmeriStar]

From your post, I'm assuming this is a new problem.
Just a thought. Did the service include an airfilter change? You might want to verify that the filter element was installed correctly. Black smoke is very abnormal to see from a DD60.

[Jon Wehrenberg]

Obviously a dirty filter will cause less air flow to the turbo and the engine, but if I recall correctly DDEC meters fuel based on air flow so a dirty filter should just result in a loss of power and not black smoke.

Turbo boost sensor? Is the rubber hose to it tight and not cracked? Its on the intake manifold. Rectangular black plastic box about the size of a deck of cards or maybe a little smaller.

[grantracy]

This is right up there with the miracle at Lourdes...drove about a 100miles and stopped at Pilot ,purchased injector cleaner/fuel additive,problem went away after a very short period of time....is it possible I actually fixed something on this beast for 7 dollars? I will let it sit overnight and see if it loads up again...possible stuck float? ( kidding)

[travelite]

Jon,

I had a badly cracked charge air cooler and I still pulled 28 plus psi of boost. Turns out that with a bad CAC, you still get the boost but the charge is super hot and less dense. I also had some black smoke since the oxygen wasn't there to burn the fuel. Another tell tale sign of a cracked CAC is an excessive exhaust gas temperature. With a bad CAC my EGT would hit 1200 plus if I let it. I learned to downshift and power down to keep the EGT's less than 1000. With my new Duralite CAC the EGT's don't go above 850 degF.

[Jon Wehrenberg]

We just learned that the intercooler (CAC) can have a leak and we still see boost.

I notice your concern about EGTs. Where is the limit for EGTs shown? On my plane I can get EGTs approaching 1700 and people freak out when they hear that. Yet unless there is a limit (on my plane I don't even have a turbo inlet temperature limit although subsequent models had a 1650 limit. On my engine there is no specified EGT limit, nor do I have pyros for the Series 60 such as I had with the 8V92.

The EGTs are a function of the mixture and if your EGTs climb with a failed intercooler that means your mixture is richer so under ordinary operation your engine is likely running lean of peak, confirmed by the fact the EGTs went down when the charge air was more dense. Very interesting and it explains why we get such good mileage, and since the engines are running lean of peak the internal cyclinder pressures are low (relatively speaking) which is healthier for the engine.

[rbeecher]

Granville,

Was this a DD of Miami service? Last time I was there, a couple of months before the Kerrville trip we didn't make, I discovered they have to be watched carefully. Overfilled the oil significantly and didn't provide the oil analisys report, for the second time. They also forgot to check the transmission sensor which was bad. One of the DD road techs came out to the house and corrected the oil level.

Richard Beecher
2002 Marathon XLII
2010 Mini Cooper S

[grantracy]

No it wasn't dd of Miami ...don't know if my problems are service related or not