Sable V6-183 3.0L DOHC VIN S MFI (1997)
Variable Induction System: Description and Operation
The air intake system utilizes a secondary intake port along with a primary intake port. The secondary port is opened and closed by an electronically
operated intake manifold runner control (IMRC) deactivation motor, thus improving low and mid-range torque and fuel efficiency.
The air induction system improves engine performance by using the intake manifold runner control (IMRC) assemblies as follows:
-
The intake manifold has two runners per cylinder, feeding each of the intake parts in the cylinder heads.
-
The IMRC assemblies are located between the intake manifold and cylinder heads, providing two air passages for each cylinder.
-
One air passage is always open and the other passage switches from closed to open by means of a valve plate.
-
Below 3000 rpm, this valve plate is closed to improve low-speed and cold engine performance.
-
Above 3000 rpm, this valve plate opens to improve high-speed engine performance.
The valve plates are opened and closed by the IMRC deactivation motor, which is controlled by the powertrain control module (PCM).
