Knock sensor gauge idea!

[turbovanman²]

Based on Rob's thread on knock sensors, the voltage has to be at a certain voltage to be real knock, I think it's 4.5 volts but whatever at this point, doesn't matter. I am having issues with my SES light always flickering or coming on, so I was thinking, why not have a small LED display showing the voltage, so then you know instantly if its real knock or phantom.

So would simply wiring a display from the knock sensor wire and ground work or would that mess up its performance?

[roachjuice]

[turbovanman²]

????????????

[shackwrrr]

Sure a gauge like the Dawes that has a few colored leds would work.

[turbovanman²]

Sure a gauge like the Dawes that has a few colored leds would work.

Hmm, that's not a bad idea, but we don't really need all those LED's, just one would do that job, and easier to see at a glance too.

[cordes]

Why not properly set your knock table so that the CEL comes on during actual knock?

[turbovanman²]

Why not properly set your knock table so that the CEL comes on during actual knock?

Did you not read what I wrote?

[cordes]

I did, and I don't see a problem. Why is your gauge flickering? You can change all of the knock parameters so far as I'm aware. I don't see why your light should come on unless you want it to.

[turbovanman²]

Its coming on all by itself, has nothing to with knock, so I can't trust it anymore, hence my need for another way to monitor knock.

[GLHNSLHT2]

The voltage output that says you're knocking or not is not a linear curve.

[Force Fed Mopar]

You can log the knock sensor voltage with MPScan. The voltage that actually indicates knock can vary from sensor to sensor and engine to engine. I actually have mine set to 3v at 2500 and 3.7v at 6k, IIRC. But my knock sensor is new and very sensitive.

[turbovanman²]

Can't remember but does the sensor generate A/C or DC voltage?

The voltage output that says you're knocking or not is not a linear curve.

True, but I can set the LED or whatever I choose to start to come on at the known voltage of knock.

You can log the knock sensor voltage with MPScan. The voltage that actually indicates knock can vary from sensor to sensor and engine to engine. I actually have mine set to 3v at 2500 and 3.7v at 6k, IIRC. But my knock sensor is new and very sensitive.

That would help figure out where I start to knock as right now, my SES light is useless,

[Force Fed Mopar]

DC volts. I think anyway lol.

[RoadWarrior222]

There's a bargraph module that will work for that, just got some the other week...
http://www.turbo-mopar.com/forums/sh...ighlight=volts

Basically, you'd put in the resistors for 5v, and it would flicker low at low knock, and nearly full scale for real knock... or there's a way of setting a bottom threshold with a variable resistor so you don't have it flickering all the time, but I think that would change the scaling, so say threshold was 3v the scale would be 3v to 5v across 10 LEDs, so when it's flickering at the left it's just hitting over 3v

[turbovanman²]

Yeah, my friend is going to make me an adjustable LED setup,

[ShelGame]

True, but I can set the LED or whatever I choose to start to come on at the known voltage of knock.

If you KNOW the voltage at every RPM that causes actual knock, why not just re-calibrate the knock threshold line? Then the light would only come on when you get actual knock.

The knock retard system works like this:

The knock sensor outputs an AC-type voltage the amplitude of which is proportional to the noise that the engine makes.

Many things in the engine make noise. Mostly the combustion itself. Knock (ie, poor combustion) is just 'noisier'.

There's some circuity in the ECU that converts the knock sensor AC to DC that can be read by the A2D converter in the processor.

Someone, somewhere, within Chrysler, long ago, sat down with a scope and a voltmeter and listened to the engine under various load conditions sometimes intentionally inducing knock while recording the voltage. They used that data to generate a knock voltage curve. Then, they took some voltage off of that for when the chambers get carbon built up, and for when you buy cheap gas, and for when the rings get bad and you start burning oil, etc.

That line gets programmed into the computer. Any voltage over it the computer 'thinks' is knock and timing is retarded until the voltage goes down. The computer actually has no way of knowing what is 'real' knock and what is just normal engine noise - outside of that calibrated line.

The CEL light in the Turbonator (and BB60, LB60) cals comes on only when there is active knock retard - IE when the knock voltage is over the threshold.

So, if you know what the threshold is for every RPM, why not just fix the threshold line instead of making a new gadget?

Finally, the 'actual' knock threshold is going to be different for each and every engine. Even 2 completely stock engines will have slightly different 'actual' knock voltage thresholds due to wear, machining tolerance, plug indexing, etc.

If you're running a stock 2.5 knock threshold on a 2.5 TIII, then it's not going to be right. The TIII knock threshold should be closer, actually. But, even that is very conservative and probably not what you want to run...

[RoadWarrior222]

instead of making a new gadget?

LUL whut? But a new gadget is a new gadget, and it would have blinky lights!


But Rob maketh sense that you don't want retard when you don't need it, so haxx0r teh cal already.

... although he also wanted a new gadget when his stage limiter didn't work.

[turbovanman²]

If you KNOW the voltage at every RPM that causes actual knock, why not just re-calibrate the knock threshold line? Then the light would only come on when you get actual knock.

The knock retard system works like this:

The knock sensor outputs an AC-type voltage the amplitude of which is proportional to the noise that the engine makes.

Many things in the engine make noise. Mostly the combustion itself. Knock (ie, poor combustion) is just 'noisier'.

There's some circuity in the ECU that converts the knock sensor AC to DC that can be read by the A2D converter in the processor.

Someone, somewhere, within Chrysler, long ago, sat down with a scope and a voltmeter and listened to the engine under various load conditions sometimes intentionally inducing knock while recording the voltage. They used that data to generate a knock voltage curve. Then, they took some voltage off of that for when the chambers get carbon built up, and for when you buy cheap gas, and for when the rings get bad and you start burning oil, etc.

That line gets programmed into the computer. Any voltage over it the computer 'thinks' is knock and timing is retarded until the voltage goes down. The computer actually has no way of knowing what is 'real' knock and what is just normal engine noise - outside of that calibrated line.

The CEL light in the Turbonator (and BB60, LB60) cals comes on only when there is active knock retard - IE when the knock voltage is over the threshold.

So, if you know what the threshold is for every RPM, why not just fix the threshold line instead of making a new gadget?

Finally, the 'actual' knock threshold is going to be different for each and every engine. Even 2 completely stock engines will have slightly different 'actual' knock voltage thresholds due to wear, machining tolerance, plug indexing, etc.

If you're running a stock 2.5 knock threshold on a 2.5 TIII, then it's not going to be right. The TIII knock threshold should be closer, actually. But, even that is very conservative and probably not what you want to run...

Your not getting it Rob, my SES light comes on by its own whenever it wants, already said this twice, so It can't be used right now to monitor knock as its always flashing on and off. I can't figure out why and tired of working on the damn thing, so this is my fix for now.

[RoadWarrior222]

Didya check for codes?

[ShelGame]

Your not getting it Rob, my SES light comes on by its own whenever it wants, already said this twice, so It can't be used right now to monitor knock as its always flashing on and off. I can't figure out why and tired of working on the damn thing, so this is my fix for now.

Ohhhh.... Short in the dash? Or caused by codes?