Daihatsu F300 Service Manual page 1347

EMISSION CONTROL SYSTEM
SPARK DELAY SYSTEM
During an acceleration period, this system reduces the HC and NOx emissions generated during the transient
period by retarding the ignition advance timing temporarily. This is accomplished by means of the VTV which
retards the applicat10n of a negative pressure being applied to the main diaphragm of the distributor vacuum
advancer through the carburetor advance port.
Auxiliary diaphragm chamber
Unit inspection of spark delay system
1. Remove the VTV from engine.
2. Inspection of
vnJ
(1) Blow your breath into the vrv carburetor side (side B).
Ensure that the air passes through without restriction.
If significant restriction exists, replace the vrv.
(2) Blow your bFeath into the VTV distributor side (side A).
Ensure that there is restriction.
If no restriction exists, replace the VTV.
3. Install the VTV to the engine.
EC-8
vrv
Advance
port
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