Holley knock sensor calibration question

randy merritt

randy merritt

Donating Member
One thing I still have not figured out on the Holley is how to calibrate the knock sensor so that it will actually retard timing when knock is present. As far as I know, everyone running the Holley on our trucks just disables the knock retard function.

Here is my idea. I will take a stockish truck with a stock computer and use a slide hammer dropped from a repeatable height to "knock" on the motor at various locations and record the knock induced. I will then repeat the same procedure on my truck in the same locations and drop heights, then adjust the parameters on the Holley to try and reproduce the same knock retard. This is kind of similar to how I got the speed input to work properly. Trial and error.

Any thoughts, or has someone else figured out the correct knock retard parameters to make the knock retard function work properly already?

This is not a crisis, but just something that I would like to figure out.
 
sytyguy

sytyguy

Moderated User
Re: Holley knock sensor calibration question

Randy, do you have a good oscilloscope?

A knock sensor is a piezo electric device that will alter resistance as it is excited. The presence of knock is detected by the use of a series of filters, detection schemes, and correlation to other frequency domain signals that might be present. When a "knock event" occurs, there is a shock wave produced in the combustion chamber. The resonant, one wire sensors we use have a spectral signature that corresponds to a certain frequency where this wave might occur. Due to that, there is no guarantee that the vibration induced from the test method you propose will emulate pre-ignition vibrations. Having said that, your method is as good as any I've seen (I've seen air chisels used on blocks, etc...)

Outside of having a spectral analysis done on the sensor, I'm unfamiliar with a way to determine it. You could have a local tech school or college do an analysis for you or you could guess. I know the 5.7L Vortec sensor has a singular resonance of 10.5khz and I've seen literature stating that most of the late 80's/early 90's GM sensors were made with one of the following:

75mm bore is about 7.0 kHz
94mm bore is about 6.0 kHz
110mm bore is about 5.2 kHz

Holley's own literature states to use 5.2-6.5 khz when using the 10456288 sensor, which is the NA 4.3,5.0, 5.7, etc... sensor from the 80's/90's.

That's a start.
 
sytyguy

sytyguy

Moderated User
Re: Holley knock sensor calibration question

One method I have used in the past to test a KS is to increase spark advance in a given range by, say, 4 degrees and see if I get knock. Let's say I start to see 2 degrees of knock in that given range....now, go back and add 2 more degrees to that range. Did knock go from 2 to 4 degrees? If so, the KS seems to be responding properly. If not, did the range or external factors change? If not, sensor may be bad. The nice thing about this method is that you control the amount of knock. A similar method could be used to tune your sensor.

If you do have an oscilloscope and a spare sensor, you could thread it into the head port (assuming you have one) and compare the two sensors under that condition. That's a lot of work and "ifs" but it's possible.
 
SpoolingTurbo6

SpoolingTurbo6

Donating Member
Last edited:
randy merritt

randy merritt

Donating Member
Re: Holley knock sensor calibration question

I just ordered knock sensor GM 10456288, and will set the Holley calibration per the setting that Hood has described to me. I will report back on the results.

I am partially doing this to make it easier on the next guy. We all need help from time to time.
 
randy merritt

randy merritt

Donating Member
Re: Holley knock sensor calibration question

Two questions:

Remind me of the torque value to install the knock sensor properly.

I just used the same type knock sensor pigtail that came on my stock knock sensor. Will this pigtail work with the GM 10456288 sensor?
 
bezerk

bezerk

New member
Re: Holley knock sensor calibration question

Intresting, bought a j&s system, and after setting it right i blew the trans. Still dont know if the engine is knocking.
 
randy merritt

randy merritt

Donating Member
Re: Holley knock sensor calibration question

Has anyone figured out the knock sensor function on the Holley. I.E. does anyone have a proven working knock sensor setup working with a Holley ECU on their sy/ty? I was about to attempt a setup using a different knock sensor in a different than stock location, but if someone else has already figured this out, I won't waste my time.
 
randy merritt

randy merritt

Donating Member
Re: Holley knock sensor calibration question

randy merritt said:
Has anyone figured out the knock sensor function on the Holley. I.E. does anyone have a proven working knock sensor setup working with a Holley ECU on their sy/ty? I was about to attempt a setup using a different knock sensor in a different than stock location, but if someone else has already figured this out, I won't waste my time.
Click to expand...

For future reference in case anyone is searching for this:

http://www.syty.net/forums/showpost.php?p=1110149&postcount=102
 
tbauer03

tbauer03

TRBOBOX
Re: Holley knock sensor calibration question

So will both GM Part No. 10456549 and GM 10456288 work?
I currently have 10456549 on the truck should I swap it out?
 
randy merritt

randy merritt

Donating Member
Re: Holley knock sensor calibration question

tbauer03 said:
So will both GM Part No. 10456549 and GM 10456288 work?
I currently have 10456549 on the truck should I swap it out?
Click to expand...

I'm sure you can make it work. swapping out the knock sensor is not an easy job, IMO. Give it a shot, your not going to hurt anything. Call me if you have a question. 850-251-8860
 
tbauer03

tbauer03

TRBOBOX
Re: Holley knock sensor calibration question

the motor is out of the car, physically swapping it out isn't an issue if it allows me to closely replicate your settings.
 
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