Methods and systems to derive knock sensor conditions

1. A method of diagnosing a knock sensor comprising:

receiving knock sensor data from the knock sensor, wherein the knock sensor is configured to be coupled to an engine;

applying one or more filters to the knock sensor data to derive one or more events from the knock sensor data; and

comparing the one or more events to expected engine data to evaluate whether the knock sensor is functioning properly and correctly wired, functioning properly and miswired, or not functioning properly.

2. The method of claim 1 , wherein applying one or more filters to the knock sensor data to derive the one or more events comprises deriving a combustion signature and a valve signature from the data.

3. The method of claim 2 , wherein the one or more filters comprise a low pass filter.

4. The method of claim 2 , wherein the one or more filters comprise a band pass filter.

5. The method of claim 1 , wherein comparing the one or more derived events to expected engine data comprises:

using a lookup table to determine which of the one or more events should be occurring during operation of the engine at a known time or at a known crankshaft angle position.

6. The method of claim 5 , comprising deriving that the knock sensor is functioning properly and correctly wired if the one or more events match the table events stored in the lookup table.

7. The method of claim 5 , comprising:

phase shifting the knock sensor data if the one or more events do not match the table events stored in the lookup table;

deriving that the knock sensor is functioning properly and miswired if phase shifting the knock sensor data results in the one or more events matching table events stored in the lookup table; and

deriving that the knock sensor is not functioning properly if phase shifting the knock sensor data does not result in the one or more events matching the table events stored in the lookup table.

8. The method of claim 5 , wherein table events stored in the lookup table comprise a peak firing pressure event, an intake valve closure event, or an exhaust valve closure event.

9. The method of claim 1 , further comprising receiving crankshaft angle data from a crankshaft sensor.

10. A system comprising:

an engine control unit (ECU) configured to control an engine, wherein the ECU comprises a processor configured to:

receive a noise signal sensed by a knock sensor, wherein the knock sensor is configured to be coupled to an engine;

apply one or more filters to the noise signal to derive a combustion signature, a valve signature, and one or more events from the noise signal; and

compare the one or more events to expected engine data to evaluate whether the knock sensor is functioning properly and correctly wired, functioning properly and miswired, or not functioning properly.

11. The system of claim 10 , wherein the one or more filters comprise a low pass filter to derive the combustion signature.

12. The system of claim 10 , wherein the one or more filters comprise a band pass filter to derive the combustion signature, the valve signature, or both.

13. The system of claim 10 , wherein the ECU is configured to:

use a lookup table to determine which of the one or more events are expected to be occurring during operation of the engine at a known time or at a known crankshaft angle.

14. The system of claim 13 , wherein one or more table events stored in the lookup table comprise a peak firing pressure event, an intake valve closure event, or exhaust valve closure event.

15. The system of claim 10 , wherein the ECU is further configured to receive crankshaft angle data from a crankshaft sensor.

16. A non-transitory computer readable medium comprising executable instructions that when executed cause a processor to:

receive engine noise data from a knock sensor, wherein the knock sensor is configured to be coupled to an engine;

apply one or more filters to the engine noise data to derive a combustion signature, derive a valve signature, and derive one or more events from the data; and

use a lookup table to compare the one or more events to expected engine data to evaluate whether the knock sensor is functioning properly and correctly wired, functioning properly and miswired, or not functioning properly.

17. The non-transitory computer readable medium comprising executable instructions of claim 16 , wherein the one or more filters comprise a low pass filter to derive the combustion signature.

18. The non-transitory computer readable medium comprising executable instructions of claim 16 , wherein the one or more filters comprise a band pass filter to derive the combustion signature, the valve signature, or both.

19. The non-transitory computer readable medium comprising executable instructions of claim 16 that when executed cause a processor to derive that the knock sensor is functioning properly and correctly wired if the one or more events match one or more table events stored in the lookup table.

20. The non-transitory computer readable medium comprising executable instructions of claim 16 that when executed cause a processor to:

shift the engine noise data if the one or more events do not match the one or more table events stored in the lookup table;

derive that the knock sensor is functioning properly and miswired if phase shifting the engine noise data results in the one or more events matching the one or more table events stored in the lookup table; and

deriving that the knock sensor is not functioning properly if phase shifting the engine noise data does not result in the one or more events matching the one or more table events stored in the lookup table.