Celica Supra L6-2759cc 5M Ser (1982)
Distributor Vacuum Control: Description and Operation
The Spark Control System delays the vacuum advance for a specified time to minimize nitrogen oxide (NOx) and hydrocarbon (HC) emissions.
Ignition timing is delayed within a range that will not substantially affect engine performance.
Operation
1981 5M-E Engine
When coolant temperature is below 122° F, the BVSV is closed and vacuum is applied to the distributor sub-diaphragm, regardless of throttle
position. If there is no vacuum at the advancer port, and low intake manifold vacuum at the control port, the VCV is closed and vacuum is applied
to the main diaphragm; ignition timing is advanced 8° (main), by sub-diaphragm and specified amount by main diaphragm. If there is no vacuum
at the advancer port, with high intake manifold vacuum at the control port, the VCV is open and no vacuum is applied to the main diaphragm;
timing is advanced 8°. When there is vacuum at both advancer and control ports, the VCV is open and vacuum is applied to the main diaphragm;
ignition timing is advanced 8° by sub diaphragm and specified amount by main diaphragm. When there is vacuum at the advancer port only, the
VCV is closed, and no vacuum is applied to the main diaphragm; timing is advanced 8°.
When coolant temperature is above 147° F, the BVSV is open. With the throttle valve below the advancer port, no vacuum is applied to either the
distributor sub-diaphragm or the advancer port. When there is low intake manifold vacuum at the control port, the VCV is closed and vacuum is
applied to the main diaphragm; ignition timing is advanced by the main diaphragm. When there is high intake manifold vacuum at the control
port, the VCV is open and no vacuum is applied to the main diaphragm; base timing is not changed.
When coolant temperature is above 147° F and the throttle valve is partially open, above the advancer port, vacuum is applied to the distributor
sub-diaphragm and there is vacuum at the advancer and control ports. The VCV is open and vacuum is applied to the main diaphragm. Ignition
timing is advanced by sub-vacuum and main vacuum advance diaphragms.
With the coolant temperature above 147° F, and the throttle valve fully open, vacuum is applied to the sub-diaphragm and there is vacuum at the
advancer port only. The VCV is closed and no vacuum is applied to the main diaphragm. Ignition timing is advanced by the sub-vacuum advance.
1981-82 3A-C Engine
When coolant temperature is below 122° F, TVSV ports J and M are open and the BVSV is closed. Ports T and U of the VCV are closed and
vacuum is applied to the distributor main diaphragm. Ignition timing is advanced 4° on Calif. vehicles and 8° on Federal vehicles.
When coolant temperature is above 154° F, TVSV ports M and K are open and the BVSV is open. When vacuum at the advancer port is below
2.76 inches Hg, VCV ports T and U are closed and vacuum is applied to the sub-diaphragm; timing is advanced 4° on Calif. vehicles and 8° on
Federal vehicles. When vacuum at the advancer port is above 3.54 inches Hg, VCV ports T and U are open and vacuum is applied to the sub and
main diaphragms; timing is advanced 4° (sub) and 4° main on Calif. vehicles and 8° (sub) and 8° (main) on Federal vehicles.
1981-82 4K-C Engine
When coolant temperature is below 106° F, TVSV ports J, K, L and M are closed and vacuum is applied to the distributor sub-diaphragm. Ignition
timing is advanced 10° on 1981 vehicles, or 6° on 1982 vehicles.
When coolant temperature is above 131° F, TVSV ports J, K, L and M are open. With the throttle valve below the advancer port, vacuum is
applied to the sub-diaphragm and timing is advanced 10° on 1981 vehicles, or 6° on 1982 vehicles. When the throttle valve is positioned above the
advancer port, vacuum is applied to the sub and main diaphragms. Timing is advanced 10° (sub) and as specified by the main diaphragm on 1981
vehicles, or 6° (sub) and on 1982 models.
1981-82 22R Engine
When coolant temperature is below 104° F, the BVSV is closed and there is no main vacuum advance. When coolant temperature is above 129° F,
the BVSV is open and timing is advanced normally.
1982 5M-GE Engine
When coolant temperature is below 14°, BVSV 1,2 and 3 are closed. Full vacuum is applied to the distributor main diaphragm and timing is
advanced 18°.
When coolant temperature is 39°-113°, BVSV 1 is open and BVSV 2 and 3 are closed. Full vacuum is applied to the distributor sub-diaphragm
and ignition timing is advanced 8°.
When coolant temperature is above 147° F, BVSV 1, 2 and 3 are open. When the throttle valve is positioned below control port No. 1 at engine
idle, there is no vacuum at either control port and no vacuum is applied to the distributor diaphragms; base ignition timing is not changed.
When the throttle valve is positioned between control ports 1 and 2 under cruise conditions, there is vacuum at control port No.1 and vacuum is
applied to the distributor sub-diaphragm; timing is advanced 8°. When the throttle valve is positioned above control port No. 2, at high speed
cruise, vacuum is applied to both control ports and both distributor diaphragms; ignition timing is advanced 8° (sub) and 18° (main). When throttle
is fully open, there is low vacuum at both control ports and no vacuum is applied to either distributor diaphragm; base ignition timing is not
changed.
