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.
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HOMESERVICE MANUALSTOYOTA1991SUPRA L6-3.0L DOHC TURBO (7M-GTE)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSKNOCK SENSORTESTING AND INSPECTION
1991 Toyota Supra L6-3.0L DOHC Turbo (7M-GTE)
Knock Sensor: Testing and Inspection
1991 Toyota Supra L6-3.0L DOHC Turbo (7M-GTE)SECTION Testing and Inspection
1. Warm-up engine to normal operating temperature.
2. Attach a timing light with advance indicator and a tachometer. Locate the Knock Control Sensors, (on the LH side of the engine block), and ensure that the connectors are secure.
3. While operating the engine at 2,000 rpm, check the ignition spark advance and calibrate the timing mark to 0° TDC.
4. Using a wrench or small hammer, tap the exhaust manifold and observe the timing marks.
5. The ignition timing mark should move in the retard direction, depending on the intensity and speed of the tapping.
6. If the timing mark does not retard, turn the engine off and check the wiring between the Knock Control Sensors and the ECU.
7. If no problems are found, replace the Knock Control Sensor(s) and repeat test procedure.
8. If timing still does not retard, replace the ECU.
9. Disconnect timing light and tachometer from the engine.
2. Attach a timing light with advance indicator and a tachometer. Locate the Knock Control Sensors, (on the LH side of the engine block), and ensure that the connectors are secure.
Connecting Tachometer:
3. While operating the engine at 2,000 rpm, check the ignition spark advance and calibrate the timing mark to 0° TDC.
Fig. 57 Ignition Timing:
4. Using a wrench or small hammer, tap the exhaust manifold and observe the timing marks.
5. The ignition timing mark should move in the retard direction, depending on the intensity and speed of the tapping.
6. If the timing mark does not retard, turn the engine off and check the wiring between the Knock Control Sensors and the ECU.
7. If no problems are found, replace the Knock Control Sensor(s) and repeat test procedure.
8. If timing still does not retard, replace the ECU.
9. Disconnect timing light and tachometer from the engine.
RENDER: 1.0x
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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.