IGNITION CONTROL SYSTEM (Models without E.G.R.)
EF & EC-184prose procedureApplies to GA13DS, GA14DS & GA16DS models without E.G.R. Distinguishes models with catalyzer vs without catalyzer.
System Description
Ignition timing is controlled by two systems built into the distributor to meet varying conditions during engine operation:
1) Governor advance system — Advances ignition timing in response to engine speed.
2) Vacuum advance system — Advances ignition timing by compensating for combustion speed delay when intake vacuum is high.
The thermal vacuum valve is located in the distributor vacuum line. It prevents vacuum advance during engine warm-up and improves operating performance.
OPERATION
Operation
Below 20 (68)
T.V.V.-1Close
T.V.V.-2 Models with catalyzer onlyClose
Vacuum advance — Models with catalyzerFully advanced*
Vacuum advance — Models without catalyzerNormal*
Between 20 (68) and 50 (122)
T.V.V.-1Close
T.V.V.-2 Models with catalyzer onlyOpen
Vacuum advance — Models with catalyzerNormal*
Vacuum advance — Models without catalyzerNormal*
Above 50 (122)
T.V.V.-1Open
T.V.V.-2 Models with catalyzer onlyOpen
Vacuum advance — Models with catalyzerNormal
Vacuum advance — Models without catalyzerNormal
NOTE
* Ignition timing is prevented from retarding suddenly by V.D.V. when depressing accelerator pedal.