Is it possible to attach some sort of LED to the knock sensor for knock monitoring, or is it more complex than that?

 

the knock sensor is like a little microphone, i dont think it will put out enough power to light up an LED.

 

so then are there any simple aftermarket devices that will accomplish this?

 

its not really that simple, since you need to do some pretty complex filtering to get the led to light up for knock and not all the other engine noises it picks up.

 

they sell little devices (cheap) that'll tell you if your engine is knocking...

 

so where can i get these devices?

 

anyone?

 

It is possible to do, as it has been done on DSMs for years, albeit in a slightly different manner.
On a DSM, when excessive knock is detected, they send power to the factory boost controller to open the valve completely and cut down on the amount of boost run. When you dont use the factory boost controller, or even if you do, you can tap into this wire on a DSM for powering a knock LED.

On a Honda, i'd imagine it would be possible to do something else as well. Remember, the ECU cannot filter what it detects as knock and what it does not, due to the fact that it is basically a microphone. Use the 12v output of the knock sensor and run that into an LED (make sure to put a resistor in front) and then mount the LED somewhere, whether it be in the cluster, the dash, whatever.

There you go, a knock LED in its most basic form, as it will blink whenever any form of "knock" is detected. I'm actually planning on doing this with my GSR due to the fact that my P28 w/ Hondata does not have an input for the knock sensor.

 

j&s ultra safe guard, not cheap but very effective

Rob

 

MSD sells one, last time i looked it was $120. It just an LED display and buzzer but it comes with it's own knock sensor.

 

The feedback on the hybrid forum seems to indicate that the MSD knock alert is a worthless piece of crap.

Sonny

 

Ive heard bad things about knock sensing.
Please comment on the following:
*Knock sensor will sense VTEC switchover as knock.
*Having polyurethane motor mounts or anything stiffer will make knock sensor sense engine vibration as knock.


[Modified by Quick 200k Mile Motor, 6:37 PM 11/22/2002]

 

up

 

have you or anyone you know actually tried this on a honda? i just dont see it working but i could be wrong

 

Not wanting to be an *** and burst your bubble, but this will never work. Sensing knock is much more complicated:

1. The knock sensor voltage output is not on or off, but varies in intensity

2. The knock sensor will pick up ignition and exhaust valve openning as knock (duh) as it does not filter when it listens. The ECU only listens to the sensor on the compression stroke before firing the spark.

3. The stock knock sensor was NEVER meant to contol knock under boost. Don't even think of using it like this. It does not have enough authority, even in the P72 ECU.

4. The sensor does not output any current that is usable, only voltage. You would need and amplifier/display circut made

The J&S unit is the best thing to have if you are running stock ECU. But it ain't cheap, as you can see why.

IMHO the best thing to do is never get into this situation... 1.5 deg per pound of boost on stock internals @13:1 works, I've seen it to 10 psi.

Sean

 

You could get it to light up and flash but it really isn't worthwhile, other than just using it as an indicator of "knock". Basically on DSMs we use it to get a *rough* idea as to where in the RPM band the motor is knocking. Noisy lifters, valves opening and closing, the motor vibrating, and the vtec crossover, as stated above, will cause the knock sensor to go off. So it is just a novelty type item.

 

um, once it picks op knock though, it's pretty much to late to do anything about it at that point, other than pour in some Marvel Mystery Oil and sell the bitch