Anyone been able to datalog the knock sensor?

I've tried on a 95 and a 97 with no luck..

same goes with the 6g73 v6 avengers use.. but that's another story for another time.

-- WheatKing

I thought you need an ociloscope with logging features

OBD2 management systems (and the pseudo-OBD2 95's use) do not provide knock sum information. You can't log it... you have to use an oscilliscope across the signal wires, if anything, and i don't know how you'd see knock through the waveform.

yeah I think all you can do is watch ignition timing, when the ECU detects knock it will retard timing

be aware that forged pistons sometimes fool the knock sensor into thinking the engine is knocking and will retard timing just from having forged pistons

Knock output signal-This signal is about plus and minus 2 volts and the duration depends upon what is causing the knock. The signal is about 5 thousands of a second

humm..

I would have expected the computer to keep some kind of table you could query .. much like the 4g63's computer does..

I'm asking because the knock sensor is directly related to timing. The values the computer reads from the sensor are immediately reflected in the ignition timing tables..

I'm wondering if the electronic wizards could use this to our advantage..

Basically have a box that listens and splices inline with the knock sensor, rpm signal, boost capable map.

Take these values and then fake the computers knock index by increasing the value it's seeing, which would allow for independant of tuning of the ignition timing in the ECU.. you could do an ignition map based on rpm & boost for the NA guys the opposite could happen, you might be able to actually advance the timing ala superchips icon..

If the box detected a real knock, it could pull timing and trigger a light or something to warn you and wait for you to press a "reset" button or something.

Right now I have no way of seeing if the computer is pulling timing because of knock of because of the maps. Just a wild guess.. I was hoping someone knew of a way of querying the computer for this other than using an oscillioscope.

Maybe I just think too much..

-- WheatKing

well you could always build one of these nice devices
http://www.gnttype.org/techarea/projects/projectspage.html
and when the light/buzzer comes on indicating knock you could check to see your timing retard is and know its from knock or not I suppose

as for the ICON thing, sure that would work you could fake knock to retard timing

For NA applications to advance timing I would think you would have to mess with the values from other sensors ie. IAT sensor,coolant temp sensor and any other sensor that influences timing advancement

You can't get a knock sum on *any* 2g, even a 4g6. OBD2 doesn't keep a viewable knock sum - you have to tune by timing advance.

MSD makes a knock sensor. It wont pull timing out but will let you know when it is there, which IOM is better than nothing.



The 4g63 2g guys can use the DSM link to see the knock. Dont know much about it though.

Basically what you are wanting to do is what the J&S Safeguard does. It comes with an additional knock sensor, and it listens for knock, on a per cylinder basis, and it will retard timing on the cylinder that caused the knock. Its also a boost timing retard unit, that can pull timing at whatever boost pressure you want, and how much to pull how ever you want. It can also be programmed to make the ECU go into open loop with a certain boost pressure. Its pricey, at around 600 bucks for the whole setup, but worth it to keep from detonating, and blowing your motor. Not just that, but it can be used as a sole timing retard with boost unit. The only thing that could be a downfall of this, is how accurately the knock sensor it comes with can detect actual knock, and not engine noise.

I'm starting to think that people blank out the J&S from their memory or something lol.

>I'm starting to think that people blank out the J&S from
>their memory or something lol.

Nope.. I'm quite aware of the J&S safeguard. Have been admiring that box for about 2 years..

What I want to know is when i'm driving down the road if I can see knock happening, or the onset of knock. The knock sensor is supposedly pretty sensitive.. but when I add bigger cams, stronger lifters, forged pistons, solid motor mounts etc.. how much of this rattling around in the engine is being seen as knock..

Also.. we all know these engines like to run pretty rich, just because of the weird head design.. we also know that they will detonate pretty easy if your on the edge of tuning.. knock sensor logging would come in very handy when in addition of a wideband o2 and an EGT probe.

The other part was just possibly a dirty way of doing timing retard without using a msd.

I guess Dino got it right when he said OBD-2 doesn't have a knock sum counter ala 1G 4g63 ecu did. If no one has it.. no one has it.

-- WheatKing