2-18 PERIODIC MAINTENANCE
Periodic Maintenance Procedures
If any vacuum is not within specifications, adjust the by-
pass screws [A].
View from Rear [B]
Special Tool - Pilot Screw Adjuster, A [C]: 57001-1239
Adjust the each vacuum (#1 ∼ #4) to the standard value.
Open and close the throttle valves after each measure-
Do not turn the center adjusting screw [D].
Check the vacuums as before.
If all vacuums are within the specification range, finish the
engine vacuum synchronization.
If any vacuum can not be adjusted within the specification,
replace the bypass screws #1 ∼ #4 with new ones, refer
to the following procedure.
Remove the throttle body assy (see Throttle Body Assy
Removal in the Fuel System (DFI) chapter).
Turn in the bypass screw [A] with counting the number of
turns until it seals fully but not tightly. Record the number
Check the bypass screw hole in the throttle body for car-
If any carbons accumulate, wipe the carbons off from the
hole, using a cotton pad penetrated with a high flash-point
Replace the bypass screw, spring, washer and O-ring as
Turn in the bypass screw until it seats fully but not tightly.
Do not over-tighten the bypass screw. The tapered
portion [E] of the bypass screw could be damaged.