mkIIIman089;1420153 said:
Ahhh got ya now!
They have 4 versions of it and the software allows a lot to be done with them
Knock threshold voltage?
- Thread starter mkIIIman089
- Start date
Ahhh got ya now!
They have 4 versions of it and the software allows a lot to be done with them
Do you have all that stuff running in your car now? Did you make the harness yourself or have one made from your design?
Well, I made an attempt to measure its output - don't know if I actually made any progress at all. I'd like to know, IJ. if these were even close to what you found when you worked with your knock monitor. (Doesn't seem right to me)
I could tap on the block while the car was off - the highest recorded voltage was .011 (but hey, more than 0...). So I tried testing it with the engine running and grounding it to various points including to it's plug on the harness - all resulted in very similar readings: From cold start, output slowly increased .001-.002 at a time until it levels off at about .050 and very slowly moves around between .045 and .050. As I moved the lead (not attached to the sensor) around occasionally when I 1st touched a new ground I would get a spike (probably a few milliseconds) of up to 3v...
If someone could help interpret that it'd be great, IDK if any of those readings are valid or if I did something stupid or if my VM simply doesn't read it's output properly. Seems VERY low to me but then again we are talking about a part that takes TINY vibrations and creates voltage from them.
I could tap on the block while the car was off - the highest recorded voltage was .011 (but hey, more than 0...). So I tried testing it with the engine running and grounding it to various points including to it's plug on the harness - all resulted in very similar readings: From cold start, output slowly increased .001-.002 at a time until it levels off at about .050 and very slowly moves around between .045 and .050. As I moved the lead (not attached to the sensor) around occasionally when I 1st touched a new ground I would get a spike (probably a few milliseconds) of up to 3v...
If someone could help interpret that it'd be great, IDK if any of those readings are valid or if I did something stupid or if my VM simply doesn't read it's output properly. Seems VERY low to me but then again we are talking about a part that takes TINY vibrations and creates voltage from them.
IJ.;1420121 said:
I ran into the same thing when determining whether to setup knock control on the AEM. If I set up the thresholds low enough to capture knock at cruise, it would get false knocks under load due to all the background noise. It was so frustrating I finally just gave up and wound up tuning the engine for 89 octane figuring that would be enough of a safety margin for running 91/92.
If I were to try and setup a working knock control system today, I'd look into incorporating ion-flow sensors like what BMW uses today:
http://delphi.com/manufacturers/auto/powertrain/gas/ignsys/ionized/
mkIIIman089;1420301 said:
My first guess is that its due to your volt meter. The voltage spikes don't last long -- I'd doubt a dial VM could even react in time. A digital gauge might be able to flash the peak voltage, but it would quickly drop back down to the normal. So I'd try datalogging it instead
Or use the max function if your DVM supports it. I wouldn't expect the voltage to be very high, if these things could generate much in the way of power, we'd have built a generator out of them by now.
As it is, I'm going to have to stick to the old buttered toast / pussycat arrays.
As it is, I'm going to have to stick to the old buttered toast / pussycat arrays.
From the little bit of research that I've done, the amplitude would be quite small. In millivolts.
If the documentation on the OP is correct, then the sensor isn't tuned to a certain frequency. It has a filter.
I suspect that this is correct because it jives with what IJ said about our engines being noisy under load.
If the documentation on the OP is correct, then the sensor isn't tuned to a certain frequency. It has a filter.
I suspect that this is correct because it jives with what IJ said about our engines being noisy under load.
mkIIIman089;1420158 said:
Just about to start on the new Harness (rewiring the entire car) I added the SKM and PDM's this time for a more complete package
CajunKenny;1420379 said:
Thanks, thats actually quite helpful. I didn't really expect to get a knock spike on a DVM as I figured it would probably be an extremely quick event. Some verification that I'm at least getting readings on the correct scale is good though.
I put "tuned" in quotes just because thats what came to mind at the time of that post to make what I was trying to say as clear/concise as possible. (I have a tendency to ramble at times)
IJ. said:
Someday I hope to have that sort of control, but until I hit the lottery or become an old geezer(
) I'll stick to the stock electrics.
Yeah, you'll need a scope to see it.
I don't know aggressively you're wanting to persue this; but, it would be fairly easy to build a small amplifier and have it light up a couple of LED's.
Patching it in to the factory harness might be more of a challenge though.
I don't know aggressively you're wanting to persue this; but, it would be fairly easy to build a small amplifier and have it light up a couple of LED's.
Patching it in to the factory harness might be more of a challenge though.
I was thinking it would be easiest to just get a 3rd knock sensor and plug it into the middle port on the block. Patching into those shielded wires would be a nightmare...
The knock sensors that toyota uses have a little can containing the microphone and a mechanical resonator tuned to the engines knock frequency. Knock frequrncy is determined mostly by the bore diameter.
Nissans and others use a broad band knock sensor and have an electrical resonator circuit to filter the knock signal. This type have a bolt through the middle of a ring.
Toyota also use a time dependent gate that only looks for knock signals at the correct time in the power stroke.
I have had a scope on mine a few times over the years and during light load at about 2000 rpm you can see the knock signal coming and going as the ECU operates the timing advance in closed loop mode. Peak signals were about 1 volt peak to peak. Put your foot down and you just get swamped in nosie with signals as high as 2 or 3 Volts peak to peak. And this was with a healthy rebuilt engine.
Nissans and others use a broad band knock sensor and have an electrical resonator circuit to filter the knock signal. This type have a bolt through the middle of a ring.
Toyota also use a time dependent gate that only looks for knock signals at the correct time in the power stroke.
I have had a scope on mine a few times over the years and during light load at about 2000 rpm you can see the knock signal coming and going as the ECU operates the timing advance in closed loop mode. Peak signals were about 1 volt peak to peak. Put your foot down and you just get swamped in nosie with signals as high as 2 or 3 Volts peak to peak. And this was with a healthy rebuilt engine.