2-18 PERIODIC MAINTENANCE
Periodic Maintenance Procedures
Turn in the bypass screw [A] with counting the number of
turns until it seals fully but not tightly. Record the number
Do not over tighten them. They could be damaged,
Check the bypass screw and its hole for carbon deposits.
If any carbons accumulate, wipe the carbons off from the
bypass screw and the hole, using a cotton pad penetrated
with a high flash-point solvent.
Replace the O-ring with a new one.
Apply grease to the O-ring.
Check the tapered portion [E] of the bypass screw for
wear or damage.
If the bypass screw is worn or damaged, replace it.
Turn in the bypass screw until it seats fully but not tightly.
Back out the same number of turns counted when first
turned in. This is to set the screw to its original position.
A throttle body has different "turns out" of the bypass
screw for each individual unit. On setting the bypass
screw, use the "turns out" determined during disassem-
Repeat the same procedure for other bypass screws.
Repeat the synchronization.
If the vacuums are correct, check the output voltage of
the main throttle sensor (see Main Throttle Sensor Output
Voltage Inspection in the Fuel System (DFI) chapter).
Special Tool - Throttle Sensor Setting Adapter:
Main Throttle Sensor Output Voltage
Connections to Adapter:
Digital Meter (+) → W (sensor Y/W) lead
Digital Meter (–) → BK (sensor G) lead
DC 1.02 ∼ 1.06 V at idle throttle opening
If the output voltage is out of the standard, check the in-
put voltage of the main throttle sensor (see Main Throttle
Sensor Input Voltage Inspection in the Fuel System (DFI)
Remove the vacuum gauge hoses and install the rubber
caps on the original position.