Knock Sensor - Detection and Tools

[RB's Titan]

Ok with more and more discussions about tuning and more and more about the effects of poor tuning I thought I'd start a thread on Knock or detonation and how to identify it, what it sounds like on our trucks and what tools have been tested for detection.

First we have two Bosch style knock sensors mounted under the intake manifold one on each head of the motor. The harness clip at the front right (Drivers Side) above the Cam housing is a connector for both sensors.

The detonation zone for this truck is 2800-4500RPM. This is a very crucial area as peak torque is made as well as 100% loads on the motor Not to mention that the motor stock runs lean in first gear under the loads as seen in the .PDF file below. I have marked in yellow the area where the timing was retarded.

I built a knock audio cable that I use to listen for knock via the AUX jack on the factory radio. I also have a PIE amp connected to the AUX line that helps to amplify the audio I still have to turn the volume to 30 to hear well. The cable uses parts from radio shack and can be made under $12. I’ll post a parts list so you all can make your own. I’ll also post an audio file and install pics from the truck later. Here's the audio listen for it at 5 and 10sec.
http://s93.photobucket.com/albums/l8...KnockMovie.flv

yeah listen at the 5-6 sec and 9-10sec parts of the video that is severe knock. And yes it sounds a lot like static....I want at all times a static FREE truck. I had to convert the .wav file to a movie so that I could share it. In doing so some of the crisp audio is lost.

There are much better amplified knock detection devices but they are for the tuners and can cost $700.
http://www.theknockbox.com.au/

More sound files:
http://www.theknockbox.com.au/index....ew&id=29&Itemi d=59

Another member has bought and tested another device that uses lights. He has found it to work well. Here’s a link to what I’m referring:
http://tunertools.com/articles/KnockLite.asp

There are other methods of doing this as well and each of these has their purpose. For instance NA guys would be fine with the audio cable the S/C guys due to added whining might prefer the lights.

Hope this helps you out and keeps your motor running for 100K. I would recommend a tool like this for all that are modding beyond CAI and exhaust.

[RobKar]

Very nice info RB!

[kuntao]

Good idea rb.

[RB's Titan]

I uploaded the same file twice. The how to build your own knock audio cable is now uploaded. "Knock Sensor Doc". Sorry about that.

[admw12]

So if I find the knock, what do I do next?

[RB's Titan]

you do not want knock. IF you find it then you need to get rid of it by tuning or changing fuel or visiting your dealer. Do you have knock?

[ablexus]

The easiest way to correct for knock is to upgrade your fuel and try again. Generally, the more advanced the timing, the more risk you have of developing knock. This tool could be INVALUABLE for setting a guide of "when to use higher grade fuel" based on modifications.

Andrew

[Wildmike]

I have the 2* advance and always runs premium. The only time I get knock is before the engine is fully warmed up and at 1/4 to half throttle. I never give more than 1/4 to 1/2 throttle on a cold engine. Now if I baby it during warmup no knock. Once the engine is warmed up no knock at any throttle opening.

[loufish]

Are you sure the factory Knock sensors make good acustic sensors?
The are powered by the PCM, and ground themselves during "knock", the schematic shows pulling of the powered side of the sensor, doesn't look like a good sensor for creating sound...

[RB's Titan]

they work well...give it a try it less than $12USD and 30 minutes. I can hear my electric fans come on and the bass in rockford fosgate sub resonates.

This was recorded on my laptop:
http://s93.photobucket.com/albums/l8...KnockMovie.flv

[DawgBone]

Excellent info, RB - Thanks!

[RB's Titan]

Those of you with Uprev tunes that are requesting a 93 tune and ony have 89 fuel available better listen for your knock. In my experience the branded pump gas even 93 is not all that good year round.

[kha4079]

what the heck is knock about.....

[Papa_D]

Originally Posted by kha4079

what the heck is knock about.....

"Knock Knock"
"who's there?" "Detonation" "I wasn't expecting you under my hood, what do you want?" "Oh nothing much, I just want to blow up a piston or two", lol. This is a real good reason I haven't switched to a performance tune with my cams yet, I haven't done any data logging.

[timlloyd951]

ok getting a bit confused. i have the 2 degree timing advance, f5 intake and flowmaster exhaust, should i start listening for knock? or do you guys have all the uprev tuning and more mods