Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Have you had any fault codes scanned yet?
There are two things that usually cause this problem. 1. Is the egr valve sticks open, dumping boost pressure into the exhaust instead of the engine. 2. Is the inlet port shut off flaps stick, causing not enough boost pressure into the engine. Usually both of these items will code up in the CDI engine computer, not necessarily setting a check engine light.