The rings should fit perfectly parallel to groove surfaces.
If not, replace the piston and all the piston rings.

Piston Ring/Groove Clearance Standard:
Top 0.03
0.07 mm (0.0012
0.0028 in.)
Second 0.03
0.06 mm (0.0012
0.0024 in.)
Service Limit:
Top 0.17 mm (0.0067 in.)
Second 0.16 mm (0.0063 in.)
Piston Wear Inspection
Piston Ring Groove Width InspectionGeneral Lubrication
Lubricate the points shown below,
with either motor oil or regular grease,
in accordance with the Periodic Maintenance
Chart or whenever the vehicle
has been operated under wet or rainy
conditions.
Before lubricating each part, clean off
any rusty spots with rust remover and
wipe off any g ...
Water Temperature Sensor Output Voltage Inspection
NOTE
Be sure the battery is fully charged.
Turn the ignition switch to OFF.
Remove the throttle body assy (see Throttle Body Assy
Removal in the Fuel System (DFI) chapter).
Disconnect the water temperature sensor connector and
connect the measuring adapter [A] between these connectors
...
Backups
The ECU takes the following measures to prevent engine damage when the
DFI, ignition, S-KTRC
or immobilizer system parts have troubles.
Note:
(1): D-J Method: When the engine load is light like at idling or low
speed, the ECU determines the
injection quantity by calculating fr ...