  This paper presents a method to enhance fault isolation without adding
physical sensors on a turbocharged spark ignited petrol engine system by
designing additional residuals from an initial observer-based residuals setup.
The best candidates from all potential additional residuals are selected using
the concept of sequential residual generation to ensure best fault isolation
performance for the least number of additional residuals required. A simulation
testbed is used to generate realistic engine data for the design of the
additional residuals and the fault isolation performance is verified using
structural analysis method.
