Knock Sensor Parameters

[mikedsilva]

curious if anyone knows how the motronic on 964 and 993, use the data generated by the knock sensors, to retard ignition?

im looking at setting up knock control on my engnine, using the std style Bosch donut sensors....

[mysocal911]

Originally Posted by mikedsilva

curious if anyone knows how the motronic on 964 and 993, use the data generated by the knock sensors, to retard ignition?

im looking at setting up knock control on my engnine, using the std style Bosch donut sensors....

The 964 DME ECM has a special microcontroller chip to process the signals from the knock sensors. Digital signal processing (DSP) is defined here;

https://www.ti.com/lit/an/spra039/spra039.pdf?ts=1724952016286&ref_url=https%253A%252F%252Fwww.google.com%252F

The 993 DME ECM used a more powerful processor chip which has DSP capability.

[mikedsilva]

Thanks for this. However I flunked engineeering at Uni so didn't quite follow all the math.

I've just had my first session on the dyno and trying to understand how to set up the knock sensors on the EMU Black.
I've screen shot the screen and also the instructions from the manual.

My understanding of the instructions is
- set the operating frequency based on bore diameter in my case 97mm.
- Adjust the gain so that during all NORMAL non knocking engine operation, the sensor output voltage doesnt exceed 3v.
- Then fill in the ENGINE NOISE TABLE with those values i think.

So the idea is if the sensor generates a vvoltage ABOVE what is listed in the table, then it is interpreted as KNOCK and is dealt with depending on what's keyed into the ACTION table.

Sound about right?
If so, should the ENGINE NOISE TABLE be populated with voltages a little higher than what the sensor read during normal non knocking operation? So that there is a buffer between a genuine knock event and normal engine sound?

[mysocal911]

Originally Posted by mikedsilva

Thanks for this. However I flunked engineeering at Uni so didn't quite follow all the math.

I've just had my first session on the dyno and trying to understand how to set up the knock sensors on the EMU Black.
I've screen shot the screen and also the instructions from the manual.

My understanding of the instructions is
- set the operating frequency based on bore diameter in my case 97mm.
- Adjust the gain so that during all NORMAL non knocking engine operation, the sensor output voltage doesnt exceed 3v.
- Then fill in the ENGINE NOISE TABLE with those values i think.

So the idea is if the sensor generates a vvoltage ABOVE what is listed in the table, then it is interpreted as KNOCK and is dealt with depending on what's keyed into the ACTION table.

Sound about right?
If so, should the ENGINE NOISE TABLE be populated with voltages a little higher than what the sensor read during normal non knocking operation? So that there is a buffer between a genuine knock event and normal engine sound?

There's a reason Porsche uses the digital technology referenced, and not the Mickey Mouse method of testing a simple analog signal for knocks! It's laughable.

Barrels, heads & pistons are cheap, right?

Good luck!

[mikedsilva]

Originally Posted by mysocal911

There's a reason Porsche uses the digital technology referenced, and not the Mickey Mouse method of testing a simple analog signal for knocks! It's laughable.

Barrels, heads & pistons are cheap, right?

Good luck!

awesome...