PERIODIC MAINTENANCE 2-17
Maintenance Procedure
•
Connect a vacuum gauge (special tool) and hoses [A] to
the fittings on the throttle body.
Special Tool - Vacuum Gauge: 57001-1369
•
Connect a highly accurate tachometer to one of the stick
coil primary leads.
•
Connect:
Fuel Pump Lead Connector
Extension Tube [A]
Special Tool - Extension Tube: 57001-1578
•
Start the engine and warm it up thoroughly.
•
Check the idle speed, using a highly accurate tachometer
[B].
If the idle speed is out of the specified range, adjust it with
the adjust screw.
CAUTION
Do not measure the idle speed by the tachometer of
the meter unit.
•
While idling the engine, inspect the throttle body vacuum,
using the vacuum gauge [C].
Throttle Body Vacuum
Standard: 31.5 ±1.3 kPa (236 ±10 mmHg) at Idle Speed
1 100 ±50 r/min (rpm)
If any vacuum is not within specifications, first synchro-
nize the balance of the left (#1, #2 throttle valves) and
right (#3, #4 throttle valves) assemblies.
Example:
#1: 210 mmHg
#2: 240 mmHg
#3: 200 mmHg
#4: 220 mmHg
•
With the engine at the correct idle speed, equalize higher
vacuum of #1 or #2 (for example 240 mmHg) to higher
vacuum of #3 or #4 (for example 220 mmHg) by turning
the center adjusting screw [A].
NOTE
○
After adjustment, the final vacuum measurement be-
tween the highest throttle valves may not be 240 mmHg
(for example). The goal is to have the highest two vac-
uums between the left (#1 and #2) and right (#3 and #4)
banks be the same and be within the service limits.
•
Open and close the throttle after each measurement, and
adjust the idle speed as necessary.
•
Once the throttle valves have been synchronized, inspect
output voltage of the main throttle sensor to ensure proper
operation (procedure is explained at the end of this sec-
tion).
