Purpose, Function
By lengthening the exhaust passage, the transmission of exhaust pressure waves to other cylinders can be delayed, and the amount of gas exhausted from a cylinder and forced back inside the combustion chamber is reduced By reducing the residual gas, the temperature inside the combustion chamber is reduced and the occurrence of knocking even at a high compression ratio is inhibited.
Construction
The exhaust manifold is installed to the rear of the engine. In addition, the catalytic converter (WU-TWC) is integrated (WU-TWC).

When the No.1 cylinder is at the intake stroke, the No.3 cylinder is at the exhaust stroke. By inducing the high temperature gas exhausted from the No.3 cylinder into the No.1 cylinder, the high temperature gas in the No.1 cylinder remains. If the amount of residual gas is high, the temperature in the combustion chamber rises and knocking can easily occur. With the 4-2-1 exhaust system, the transmission of exhaust pressure waves between each cylinder is delayed by the long exhaust pipes.

Exhaust System Removal/InstallationBattery [Skyactiv G 2.0]
Purpose, Function
The battery stores electricity generated by the generator. In addition, it
supplies power to electronic devices if necessary.
Construction
The battery is installed in the engine compartment. (vehicle left)
Fail-safe
Function not equipped.
...
Propeller Shaft Inspection
1. Measure the propeller shaft center runout using the dial gauge.
If it exceeds the maximum specification, replace the propeller shaft as a
single component.
Propeller shaft maximum runout
0.8 mm {0.031 in}
2. Inspect the play and rotation of the joint by turning ...
Car Navigation Unit Removal/Installation
CAUTION:
The audio unit communicates with the car-navigation unit and records the
presence/non-presence of the car-navigation unit when the ignition is switched
to ACC or ON (engine off or on) after connecting the negative battery cable.
If the commander switch is installed ...