Series 50 – Section 2.27 Knock Sensor and Signal to Noise Enhancement Filter (S.n.e.f.) Module for the Series 50G Automotive Engines

Section 2.27
Knock Sensor and Signal to Noise Enhancement Filter (S.n.e.f.) Module for the Series 50G Automotive Engines

The Knock Sensor is mounted in the cylinder head or in the left side of the cylinder block. See Figure "Knock Sensor and Signal to Noise Enhancement Filter (S.N.E.F.) Module for Series 50G Automotive " . The sensor works in conjunction with a Signal to Noise Enhancement Filter (S.N.E.F.) module which is mounted to a bracket located on the left side of the cylinder block. ‪

1. S.N.E.F. Module‪	7. Regulator Gas Inlet Tee‪
2. Air Compressor‪	8. Manifold Pressure "Boost" Sensor‪
3. PSV‪	9. Barometric Pressure Sensor‪
4. Fuel Mixer‪	10. Oxygen Sensor Interface Module‪
5. Throttle‪	11. DDEC ECM‪
6. Low Pressure Regulator‪	12. Knock Sensor‪

Figure 1. Knock Sensor and Signal to Noise Enhancement Filter (S.N.E.F.) Module for Series 50G Automotive

The Knock Sensor and S.N.E.F. module provide a signal to DDEC which is proportional to the knock level. DDEC uses the data in engine protection logic. The knock sensor is electrically connected to the S.N.E.F. module through the sensor wiring harness. The S.N.E.F. module is electrically connected to the ECM and to battery power through the engine sensor harness. The output from the S.N.E.F. module can be monitored using the Diagnostic Data Reader (DDR). The output is displayed as knock level. ‪

Section 2.27.1
Replacement of Knock Sensor and S.N.E.F. Module

The knock sensor and S.N.E.F. module are not serviceable and must be replaced as an assembly. No adjustments are required.‪

Section 2.27.2
Removal of Knock Sensor and S.N.E.F. Module

Remove the knock sensor as follows:‪

1. Disengage the connector between the knock sensor and engine sensor harness.
2. Loosen and remove the sensor.

Remove the S.N.E.F. module as follows:‪

1. Disconnect S.N.E.F. module connector from the engine sensor harness.
2. Remove two M6 bolts that attach the module to the bracket.
3. Remove module from bracket.

Section 2.27.3
Installation of Knock Sensor and S.N.E.F. Module

Install the knock sensor as follows:‪

1. Install sensor in boss and torque to 17–21 N·m (2.5–3.0 lb·ft).
2. Connect knock sensor pigtail to sensor wiring harness connector.

Install the S.N.E.F. module as follows:‪

1. Position module on bracket and install two M6 attaching bolts.
2. Connect to engine sensor wire harness.
3. Turn the ignition to the "ON" position. Observe or read any diagnostic codes. If any codes other than 25 appears, refer to the DDEC II Troubleshooting Guide, 6SE489, or DDEC  III/IV Single ECM Troubleshooting Guide, 6SE497