Rich,

That's what the factory calls it...consists of:
1. a pressure line from the Intake Manifold to the SwitchOver valve
(Mounted on the Faux FireWall just forward of the Brake Booster compartment) 2.A line from the SwitchOver Valve to the ALDA.
3.A Sensor screwed into the Intake Manifold that,When pressure in the Intake
exceeds the set Boost point,Grounds the SwitchOver Valve which then denys
Boost to the ALDA...AND as a result the ALDA "STRANGLES" fuel enrichment
to save the engine.

Problem is the pressure line from the Intake to the SwitchOver Valve,
and thence to the ALDA gets clogged up with all the EGR GOO and the ALDA seeing No Boost does not Enrich the Fuel Flow.

I'll bet if you:
1.Take the Pressure lines off and clean them out with Brake Parts Cleaner.
1a.Clean out the nipple the pressure line uses in the Intake.
2.Take the Switch Over Valve off and using Brake Parts Cleaner to blow out
all the GOO.
3.Unscrew the Sensor and Clean out it's port.

Your OM602's PERFORMANCE will amaze you!

Ideally you'd take the Whole Intake Manifold Off and fill it up with BioDiesel
to soak for a day or so and then clean it out.

BC's EGR deletion kit will remove the SOOT from the EGR part of the GOO!

__________________
'84 300SD sold
124.128