At this point they are considered incertae sedis;in other words, we know that they are theropods; and probably coelurosaurs; but we don't know who they are related to or how they fit into the big picture of theropod phylogeny.
Idle speed is adjusted by means of the idle control valve, which is a solenoid-operated valve that is generally automatically adjusted by a computer. One problem that can occur with this component is a loss of power (from a severed line or a short) but a more common problem is simply dirt and grime.
Even more basic than the discrete directional-control valve is the digital valve. As in digital electronics, digital valves operate either on or off. Whereas discrete valves generally use a spool to achieve two, three, or more positions, discrete valves use a plunger, poppet, or ball that seals against a seat.