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/InstallationOn Board Diagnostic System PID/Data Monitor Inspection [Fw6 A EL, Fw6 Ax EL]
1. Connect the M-MDS to the DLC-2.
2. After the vehicle is identified, select the following items from the initialization
screen of the M-MDS.
a. Select “DataLogger”.
b. Select “Modules”.
c. Select “TCM”.
3. Select the applicable PID from the PID table.
4. Verify the PID da ...
Clutch Cover Inspection [C66 M R]
1. Remove the clutch cover..
2. Perform the following procedures to inspect the clutch cover.
If it exceeds the maximum specification, replace the clutch cover..
a. Measure the wear of the diaphragm spring fingers.
Clutch cover diaphragm spring fingers maximum depth
0.6 ...
Flywheel Inspection [C66 M R]
1. Remove the flywheel..
2. Perform the following procedures to inspect the flywheel.
If there is any malfunction or it exceeds the maximum specification, replace
the flywheel..
a. Inspect the surface that contacts the clutch disc for scratches, nicks, and
discoloration.
...