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Home Made Knock Sensor?

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motorhead

motorhead mike
Joined
Sep 9, 2001
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Anyone ever done it? Considered it?

I am. A dual alert (audible and non-progressive visual)

Well, actually I am just paying for it... my brother the "auto-engineering" student is building it.

Does anyone know the "voltage" range for both the Knock Sensor and the ESC Module?

Which would be better to tap into?

I imagine the ESC, since it likely pre-amplifies the signal for the ECM read it. But, we can always "boost" the knock signal ourselves.

We are considering either a pair of transistors or the use of a S.C.R. (signal control relay).

Any thoughts?

<note: I am not trying to mess with the aftermarket we have here, I am just simply tapped from my contributions to it this year (see sig)>
 
Real basic information. The signal going to the ecm is either a given voltage (8.8 to 9.2 range-best of memory) or there is NO voltage.
The computer measures the amount of time the voltage isn't present and adjusts the timing based on the chip parameters.

This was how it was explained to me in the early 90s.

A electrical tech made me a voltage comparison circuit with a LED and I have been using it since 1992. The longer the led stays on the more severe the knock.

Gary :cool:
 
How about something a little more informative? Like which cylinder is knocking, or maybe one that can distinguish between real knock and false knock?

Dave
 
Yeah how about it! You in production yet? ;)

How do you determine real knock from false knock? :confused:
 
Uh, just trying to make Mr. T think a little bit. How do you determine real or false knock? I guess you'll have to think a little bit!:D

Dave
 
Well the good news is that if they go after the ESC module then the "knock or noise" decision has already been made, for better or for worse :) But if you decide to go before the ESC, well your auto engineering student better know a heck of alot about analog electronics, engines, knock detection, etc. :)

TurboTR
 
Hey keep us up to speed on how this goes, my brother is an electrical engineer with a flair for automotive (so much so that it makes my head spin).

I figure if we plan on making our own scanmaster tool, we can probably build a few more things too.
 
Originally posted by gnjones231
Uh, just trying to make Mr. T think a little bit. How do you determine real or false knock? I guess you'll have to think a little bit!:D
Dave
Click to expand...

Cold,
brrrrr,
cloaking devise engaged.
 
I designed something similar to what you are talking about back in '95 for a NASCAR engine builder. He backed out of the deal before I finished it, so I showed it to Kenny Duttweiler, and thanks to him, it was used on a project in the July '96 issue of Hot Rod magazine.

The engine was a 302 Mighty Mouse with a non-intercooled Vortech. The goal was 550 hp on 92 octane. Kenny dialed it in with a DFI and 13.5 psi on 100 octane first, the switched to 92 octane. He said the Knock Finder gave him the confidence to tune closer to the edge, and on that project engine, he said it was worth close to 100 hp.

The unit features individual cylinder knock retard, individual cylinder manual retard, and retard displays for each cylinder.

photos and description here:

http://www.jandssafeguard.com/knockfinder.html
 
Nice to see this is generating some interest. :)

We are going after the ESC... basing it on a 9v on/off system.

I am supposed to be getting the parts today... and whatever the final schematic is... and following testing... and some pics... I'll post it all.

That Knock Finder is SICK!!! :cool:
 
Very nice project and product.

Goober that was mean. :(

Thinking is for people with time and ambition....

I've got cash. :D

Methinks you would have to be sure of the KR profiles for each before filtering or equalizing.

Too risky for me. ;)
 
Geez...I didn't mean to be mean:eek: I always thought that making people think was a good thing. It sure works wonders here at work. Ahhh, the stories I could tell:D So you have more money than brains? I wish that was my case!

Now for all you people out there who have thought about how you can distinguish between real knock and false knock, here is the answer for your headache. On my car the #2 cylinder, 95% of the time, is the first to knock and retard the timing. The other 5% is the #3 cylinder. This is real knock...it's consistant. False knock would be characterized by random cylinders being the first to knock. I can also tell exactly when the knock ocurrs too. This would help corrrelate between real and false knock. Real knock generally occurs in about +-10* of TDC. False knock would occur at any time. HTH:D

(mean?)Dave
 
Hey I actually got a headache thinking about thinking.... ;)

Okay you posted the answer so you aren't as mean as others. :D

However your thinking requires the use and knowledge of a knock detector that isn't on the market or well published... yet... ;)

So do you recommend finally building that 3 layer board or waiting until I can buy one! :D
 
Originally posted by gnjones231
Geez...I didn't mean to be mean:eek: I always thought that making people think was a good thing. It sure works wonders here at work. Ahhh, the stories I could tell:D So you have more money than brains? I wish that was my case!

Now for all you people out there who have thought about how you can distinguish between real knock and false knock, here is the answer for your headache. On my car the #2 cylinder, 95% of the time, is the first to knock and retard the timing. The other 5% is the #3 cylinder. This is real knock...it's consistant. False knock would be characterized by random cylinders being the first to knock. I can also tell exactly when the knock ocurrs too. This would help corrrelate between real and false knock. Real knock generally occurs in about +-10* of TDC. False knock would occur at any time. HTH:D

(mean?)Dave
Click to expand...

Sounds like you need the RJC Power Plate! Then where will that put your theory! Huh, huh... huh?!

That's what I thought!

J/K :D

(note to self... when asking about knock detectors... don't write knock sensor :rolleyes: :) )
 
Yeah, it would be interesting to put on one of those plates and see what happens. In case you didn't know, I can also tell which cylinder makes the most and the least power:D

Dave
 
I forgot....what theories? Everything I've said is what I've measured on my car. Am I really that bad in explaining myself? Maybe I should mention that I have a one of kind high speed synchronous datalogger that I built myself. I measure just about everything you can think of. Ya know, I've been reading car mags since the early 60's, and I thought I knew quite a bit about cars by reading them. Well, after my datalogger, I realized I didn't know squat! And guess what? I'm still learning!

Dave
 
Originally posted by John at J&S
Here's a starting point for your home made knock meter. I made this several years ago. It triggers off an ESC module, and drives a bargraph display. This is probably similar to the Casper's gauge.

It's at the bottom of this page:

http://www.jandssafeguard.com/test/GNIgnition.html
Click to expand...

John, what does the face of it looks like? Are you still marketing it?
Didn't see it on your website. What price?

The combination knock & air fuel gauge looks good, but just a $$$ for priminary knock. From all I read, you need a 5 wire o2 sensor($$$$) to get real accurate reading.

Thanks,
Gary:)
 
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