Quote:
Originally Posted by Jeremy5848
The butterfly valves in the intake manifold and crossover pipe "tune" the intake and increase torque. The engine will run even if they don't work but the torque curve will be affected. The electronics that operates them is the same as operates the electronic idle control.
Jeremy
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a bit of a clarity here - because I ripped about 3 handfuls of hair while repairing my car for a dodgy idle.
the idle control is done solely by the ELR which takes reading from the tach and thermistor on the engine cylinder head.
The manifold flappers are driven by the EGR control module, it also takes reading from the tach sensor and thermistor and also the rack position.
Mine used to get stuck in "working state" - the fault was the similar wiring fault like the idle system - and the odd bit was the wiring was in beautiful shape - genuine MB replacement part of 2007 build - still it had 3 brown wires misrouted.