Theory Of Operation

The turbocharger bypass valve (surge valve) is activated during a rapid throttle change from a boosted manifold pressure to a low manifold pressure (closed throttle). The surge valve allows excess pressure between the compressor and closed throttle to escape. If this does not happen the excess pressure pulsates against the compressor vanes. The diagnostic looks for these pressure pulsations from the Throttle Inlet Pressure sensor (TIP) during the activation of the surge valve and outlined engine operating conditions.