Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1987 Porsche 928 AutomaticFACTORY OEM SERVICE PROCEDURE
Speed/Reference Mark Sensor Test
NOTE:
Test can only be performed with oscilloscope.
- Disconnect EZF ignition control unit. Connect oscilloscope positive test lead to terminal No. 7 and negative test lead to terminal No. 19 of connector. See Figure.
- Crank engine and observe pattern on oscilloscope. Screen should display oscillations of at least 2.5 volts with an integrated higher amplitude reference mark. See Fig 1.
- If speed sensor oscillations are less than 2.5 volts or if no oscillations are displayed on screen, double check connections. If okay, replace speed sensor. Speed sensor oscillations cannot be adjusted.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.