Im driving the e250 with the OM651 engine and the biturbo.

The turbo sporadically gives full boost. But usually is underboosting.

If it does give full boost its when the engine is warm.

Occasionally when decelerating, there seems to be a kick from the turbo, and the car jumps forward a little bit. Almost as if the turbo spooled up and dumped some cold air into the engine.

DPF was clogged when we first got the car, but that has been cleaned.

Turbo solenoid has also been changed. Turbo has been checked and doesnt seem to be broken, spins freely and wastegate opens and closes smoothly.

Intake has been smoke tested.

wastegate actuators have been vaccum tested.

the OBD reader reads, p029900 (boost pressure of turbocharger 1 is too low), which is strange as its not only one turbo that is underboosting, but feels like both.

Any ideas???