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Knock sensor on a non-computer controlled engine?

  
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Knock sensor on a non-computer controlled engine?

 
Rocketman422 Rocketman422
User | Posts: 81 | Joined: 02/07
Posted: 05/08/08
08:37 PM

I have heard about puting an o2 sensor in you header and using a volt meter as a low buck tuning tool. I was wondering if you can put a knock sensor in a carbed engine and do the same thing. Would you use a volt meter? What way of interpreting the sensor data would there be?  

GibTG GibTG
Guru | Posts: 931 | Joined: 08/03
Posted: 05/08/08
09:21 PM

Here's just some info I pulled off the web after a quick search, it's pretty dated though...

" You need to use a knock sensor in order to determine this.  An engine makes its best power when incipient (silent) detonation is present. This knock IS visible to a knock sensor.   There are two easy ways to do this.  One is to buy a knock sensor from a commercial vendor. The only one I know of right off the top of my head is the SafeGuard system from J&S electronics (714) 534 6975.  This is actually a knock control system that also displays knock activity.  It's expensive at $425.  I've not evaluated it so I cannot comment on its effectiveness.
The second method is to install a knock sensor on your engine and monitor it with an oscilloscope.  To get a sensor, simply visit your local car parts emporium and look in their sensors catalog.  find a sensor for an engine similar to yours that was equipped from the factory.  The sensor is acousticly tuned to the knock frequency of an engine type so it is important to match engine types.  In general, I've found that all V8 sensors, all in-line six sensors and all 4 cylinder sensors, etc, are interoperable within the engine type.

The signal must be viewed with a scope triggered from ignition pulses. This is because other engine noise can mimic knock.  What you're interested in is looking for knock from about 5 degrees after ignition
firing to about 20 degrees after top dead center on the power stroke. I have a Fluke Model 97 digital storage scope that makes this easy. It can be done with an analog scope but will require an assistant to
run the scope.  With my digital scope, I can gate the sweep from the ignition pulses and trigger the acquisition cycle on amplitude of knock signal.  Then I just drive and when the scope triggers, stop
and look at it.  With the ignition signal on the other channel, I can compute the RPM where the problem happens.

The neat thing about knock sensor is that they pick up resonances set up in the block and head stimulated by the detonation process.  This means
that the same signal can be generated with a sharp hammer rap on a solid spot on the block.  Thus you can calibrate your knock sensor without having to run the engine. " ~ John De Armond  
~Gibs

TheSilverBuick TheSilverBuick
Guru | Posts: 1227 | Joined: 02/06
Posted: 05/13/08
09:49 PM

On GM vehicles there is a Knock Sensor controller to interpret the knock signal for the ECU. Not sure what the output of it is but it's probably a readable voltage. There are tons of them in the Junkyards. Also knock sensors are tuned for certain resonance frequencies and different years/models use different frequencies (basically rpm ranges).  
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The Silver Buick- '77 Skylark coupe w/ a Fuel Injected Buick 455&TKO-600, '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428&C6. '69 Firebird replaced!

http://www.bangshift.com/forum/index.php?topic=6189.0

markspend01 markspend01
New User | Posts: 4 | Joined: 07/13
Posted: 07/16/13
02:45 AM

Hey Guys me Mark.Well i think Gib that you provide a  brilliant information about knock sensor.Thanks a lot for sharing!!


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