Serious banging and black clouds ona 3rd gen
 

Hi folks!

Usually I am more in the 2nd gen forums, but there is a CR that has me stumped. It belongs to a friend of mine.
While driving between 1200 and 2000 rpm at low loads it will sometimes make a very loud bang (as if you hit a pipe with a sledgehammer) and there is a puff of black smoke from the exhaust.
A Chrysler dealer in Italy says that it's the "exhaust pressure valve" - so his English and my Italian mix everything up now- and I have some strong doubts that the wastegate could make such a bang. With a 1960s truck I could hear this as a really worn exhaust brake...
There are no codes, the tranny fluid is good, (since the truck started doing this I suspected some kind of bindup in the auto)

So, anybody got any idea?

Thanks!

AlpineRAM

Bang
 

Is the bang coming from the front or back of truck? What kind of mods if any?

No mods, sound coming from the front of the truck as far as you can tell.

AlpineRAM

Does the truck have an exhaust brake? Maybe thats what he was calling an "exhaust pressure valve". That could explain both symptoms.

The truck has no exhaust brake, and no aftermarket accessories.
Could there be some EGR issue? (Is there an EGR on the 2005?)

Thanks!

AlpineRAM

No EGR on a 2005 in the US but not sure if they installed them earlier in Europe. Indications are of a turbo that is not very happy. The bang could be a surge and the black smoke is lots of fuel and no air.

Inspect the intake and look at the inlet to the turbo to see if there is damage or obstruction.

Also just to make sure of the sequence, is it bang then black smoke, or smoke then bang. There can be fuel system issues that could also cause the symptoms but then I thing there would be other drivability issues.

Well,the problem is that I don't have the truck at hand- After his complaints he tried to duplicate the problem with me on board, naturally there were no clunks, bangs or whatever.
But when he left I heard the bang when he turned into the mainroad, just out of sight.....
Now he went to Italy, and the banging got quite regular.
I'll try to check according to the suggestions (keep 'em coming) when the truck is back in my region.

Thanks!

AlpineRAM