Simple detenation sensor???
- Thread starter Peter
- Start date
For a non knock sensor monitored engine or for finding noises, it seems like a good idea.
But like they alude to in the beginning there are much better devises. The Knockguard is one great unit.
For the folks that aren't into reading plugs, or real fine caliber tuning, the Knockguard should be mandatory for them.
While I don't have one I've talked to the folks there alot, and probably learned more about the system then they generally share, it is based on solid engineering, and has a proven track record.
b4black
Well-Known Member
- Joined
- May 24, 2001
That's cool. That would be a great way to listen for detonation and confirm whether or not the factory ESC is work properly. It would help pinpoint the source of false knock. Need to make a trip to Radio Shack and see if they have something like that amplifier.
The J&S Safeguard would be great, but ~$450+
http://www.jandssafeguard.com/index.html
It's interesting to note the detonation resonant frequency is a function of cylinder radius. As far as I know, the 3.8 and 4.1 use the same sensor and control module.
The J&S Safeguard would be great, but ~$450+
http://www.jandssafeguard.com/index.html
It's interesting to note the detonation resonant frequency is a function of cylinder radius. As far as I know, the 3.8 and 4.1 use the same sensor and control module.
b4black
Well-Known Member
- Joined
- May 24, 2001
There a bunch of these Whisper 2000 things on ebay.
I also found out that those little tape recorders that college students use to tape lectures will work also. Some have a jack for an extrenal microphone and the play thru the headphones when recording. See those old cassette thingys are still good for something.
I also found out that those little tape recorders that college students use to tape lectures will work also. Some have a jack for an extrenal microphone and the play thru the headphones when recording. See those old cassette thingys are still good for something.
John at J&S
Member
- Joined
- Jun 19, 2002
GM knock sensors
Rich:
There are three types of knock sensors. GM terms them as non resonant (un tuned), spike resonant, and broadband resonant.
GM chose broadband resonant sensors, and manufactures them in three overlapping frequency ranges. These are 5.2kHz, 6.0kHz, and 7.0kHz.
They chose broadband for a few reasons. Combustion temperature and engine manufacturing tolerances can change the knock frequency by several hundred Hz. In addition, it requires stocking fewer part numbers.
The above information was taken from SAE paper 900488, written by three GM knock sensor engineers, and titled Combustion Knock Sensing: Sensor Selection and Application Issues.
With just three frequencies, there are still a lot of part numbers, since the sensors are manufactured with various threads and internal load resistances.
Sensors are furnished in three different load resistances, which are 3.9k, 8.2k, or 100k.
The internal resistor must match a similar resistor inside the ESC module. These two resistors form a voltage divider, setting the quiescent sensor voltage to 2.5v. Thus, the ESC can determine if the sensor becomes either open or shorted, and the ECM will set a code.
Rich:
There are three types of knock sensors. GM terms them as non resonant (un tuned), spike resonant, and broadband resonant.
GM chose broadband resonant sensors, and manufactures them in three overlapping frequency ranges. These are 5.2kHz, 6.0kHz, and 7.0kHz.
They chose broadband for a few reasons. Combustion temperature and engine manufacturing tolerances can change the knock frequency by several hundred Hz. In addition, it requires stocking fewer part numbers.
The above information was taken from SAE paper 900488, written by three GM knock sensor engineers, and titled Combustion Knock Sensing: Sensor Selection and Application Issues.
With just three frequencies, there are still a lot of part numbers, since the sensors are manufactured with various threads and internal load resistances.
Sensors are furnished in three different load resistances, which are 3.9k, 8.2k, or 100k.
The internal resistor must match a similar resistor inside the ESC module. These two resistors form a voltage divider, setting the quiescent sensor voltage to 2.5v. Thus, the ESC can determine if the sensor becomes either open or shorted, and the ECM will set a code.
