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Spark Control System Toyota Land Cruiser 60

Testing & Diagnostics 1 illustration ~327 words

DESCRIPTION & OPERATION

The spark control (SC) systems help reduce HC and CO emissions by delaying vacuum advance and lowering maximum combustion chamber temperatures. The system is designed to improve cold engine performance by advancing timing only when the engine is at normal operating temperature. Systems include a distributor with vacuum advance diaphragm, bi-metallic vacuum switching valve (BVSV), and hoses.

BI-METALLIC VACUUM SWITCHING VALVE (BVSV)

  1. Drain coolant from radiator into container. Remove BVSV and immerse in water. Using ice, lower temperature to below 86°F (30°C). Blow air into either pipe and verify that BVSV is closed.
  2. Heat water to more than 111°F (44°C). Blow air into a pipe and check that BVSV is open. Apply liquid sealer to threads of BVSV and reinstall. Fill radiator with coolant.

CHECK VALVE

Valve should close and not allow air to flow while blowing into Black pipe. Air should flow while blowing into the other pipe.

VACUUM TRANSMITTING VALVE (VTV)

Air should not flow when blowing from side A to B (as marked on valve). Air should flow easily when blowing from side B to A.

SYSTEM TESTING

  1. Connect a vacuum gauge to distributor main diaphragm hose and another vacuum gauge to distributor sub-diaphragm hose. (Схема №1) If equipped with high altitude compensation system (HAC), disconnect lower vacuum hose of HAC valve and connect it to intake manifold.
  2. Warm up engine to normal operating temperature. Pinch hose between vacuum pipe and vacuum transmitting valve (VTV). Increase engine speed to 2500 RPM and release hose. Vacuum gauge should indicate high vacuum within 2-5 seconds after releasing hose.
  3. Remove hose from VTV on vacuum pipe side. Vacuum gauge reading should drop rapidly to zero. Remove vacuum gauge and reconnect hoses.
  4. Remove distributor cap and rotor. Apply vacuum to diaphragms and verify that vacuum advancer moves. Reinstall rotor and cap. If system performed as described, testing is complete. If not, check individual components. See «COMPONENT TESTS»(/toyota/land-cruiser/60-1980-1990/remont/testing-diagnostics/#spark-control-system).
Fig. 1: Spark Control System
Scheme 1: Spark Control System

See also:
• COMPONENT TESTS

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