I've got a similar issue, namely the car smokes a lot even under the slightest acceleration. Sometimes it leaves a cloud of black smoke, sometimes just a little, but something is obviously wrong.
Now for the checks:
- my turbo does make a noise (especially when the engine cold), sounds like a loud whistling (much louder than the usual whistle)
- engine temperature is OK
- fuel consumption is within reasonable limits for a 2.4 20v (did 550 km yesterday, of which about half on the motorway, speeds between 130 and 170 km/h, 50 km on twisty country roads, going up and down, at all the speed it could take, the rest done driving "normally", i.e. speeds of 100-120 km/h and quite frequent overtakings); the average consumption ('brim-to-brim' calculation) was 8.43 l / 100 km = 33.5 MPG
- boost values seem normal - graphs based on data from FiatEcuScan show the 'desired' and 'real' boost pressure being quite in sync
- I occasionally have a blinking glowplug light upon startup (error code P0683 - glow plug control module), but I don't think it's related to this issue
Anything particular I should look for?