I experienced a poor acceleration or lack of on my 2006 E320 CDi, it would very slowly accelerate, no codes and I'm not sure what it maybe.

Are you using a scanner that can pull all the MB codes?

Generically on Diesels loss of power is often attributed to restricted fuel filter or fuel tanks screen if there is one in the system.

You could change your filters today and fill up at some station tomorrow and get contaminated fuel that will restrict the flow in the filters.

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84 300D, 82 Volvo 244Gl Diesel

Did this problem appear all at once or gradually?

Check for clogged cat also

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

I dont have a scanner and what would recommend for a OBDII scanner for this Diesel

This only happened once and 1 hour later all was fine.

This only happened once and 1 hour later all was fine. The filter was changed about 5 months ago and I have not experienced any filter issues.

It slowly appeared and stayed that way, than I parked it for about 1-2 hrs and all was fine on my return travels.

iCarSoft MBII is a good choice. Really flying blind until you have the opportunity to read the codes.... or see that there are none.

Common rail engines 648, 642, 651, have a ‘limp mode’ that it enters for faults where full power may cause more damage, but allowing limited operation to get to a workshop is allowable.

It effectively turns the car into a 240D when it happens.

The modern fuel systems don’t seem to be as prone to losing prime as the mechanical engines were. These have a pusher pump in the fuel tank to feed the filter and high pressure pump at the engine.

If you get an iCarSoft or a factory scanner on it there should be stored codes in the power train computer to lend a clue what happened.

Exhaust filter clogging is a possibility but you can read ash load and percent obstruction with the scanner.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Are you seeing that it will not rev over about 3000?

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Yep 3k hard cap is definitely limp mode. Hence the 240d level performance.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech