For this test, the accelerator pedal must be pressed all the way down and the corresponding wire must be connected to the forced downshift switch. Unscrew the vacuum supply tube from the intake manifold to the ECU and plug it. Start the engine and set the crankshaft speed to 1000 rpm. The stroboscope should show 12°.
NOTE: Since the ignition coil has two terminals, the device will show pulses for two cylinders. Therefore, to obtain the ignition timing value, the device reading must be divided by two.
Perform a check for crankshaft speeds of 2100-3050 and 3100-6500 rpm. If the stroboscope shows 16°, check the wire connecting the forced downshift switch to ground for a break, as well as the condition of the switch's insulating lining.
Full load test
Perform all prerequisites for testing as stated above and disconnect the wire from the downshift switch. The strobe light should show 16° and the RPM should increase slightly. Otherwise, check the coolant temperature sensor and the wire connecting this sensor to the ignition control unit.
Partial load test
Connect the vacuum pump to the ECU vacuum tube and create a vacuum of 0.065 kgf/cm². Increase the speed and observe the stroboscope readings. Note its readings at 1000, 2000, 3600, 4100 and 4600 rpm and divide them in half. Perform a check for a vacuum of 0.060; 0,110; 0,160; 0,210; 0,260; 0.310; 0.360 and 0.410 kgf/cm². If the coolant temperature is above 100°C after the full load test, the values of the first partial load test graph (0.060 kgf/cm²) will be 4° lower. The other graphs will be normal. To check, disconnect the wire from the temperature sensor and short it to ground.
Checking the ignition safety switch
Engage 1st gear and drive in it, pressing the accelerator pedal until the ignition safety switch is triggered at 6500 rpm. If it does not trigger, check the flywheel, switch sensor and electrical connections.
