anyone know how the knock sensor works on our car? is it a on off type of thing. i believe it is a piezo electric unit, sort of like a car alarm shock sensor. does anyone know the voltage that it switches. I want to make one of those LED's that blink when the car sees knock. I've seen them in 4g63 cars, but nobody i have seen has made them for our cars. if i can get the info i may be able to make a batch for anyone who wants one.
lates
james

It is a peizo-electric sensor. The Tech manual states that it's output increases as it detects knock, but the voiltage utput of the sensor itself does not vary to any specific pattern when monitored. I myself haven't had time to check it out, but others have.

The only thing i can think of is that the signla line does not vary by voltage, buyt by a set frequency the the ECU determines as knock. If that is the case, there is no way to directly monitor the sensor output without some fairly complex electronics that no one has much of any idea how to build.

I believe it has to be monitored or tested with an oscilliscope, which leads me to think that you would need something that can measure frequency, not voltage.

that's not how the 4g63 guys do it. it woudln't work on our knock sensor even if that was how they did it mainly becasue our knock sensor (just like all the resto fo the sensors on our cars) is retarded to say it scientifically.

A.D.P.
"...If you do too much, people become dependant. If you do to little, people loose hope. If you do it right, people won't be sure you've done anything at all."
bring it on............

The 4g guys "knock LED" is not even conbnected to the knock sensor, it is connected to the BCS (which they all disconnect anyway). Sometimes (like, say, when knock occurs) the ecu will work the BCS to lower boost. They monitor the BCS with the LED, believing that if the ECU is working the BCS, then they might be getting knock. However, i bleive the BCS is probably used for more than just knock related boost control, so it is not entirely accurate nor useful in my opinion.

from what i know of piezoelectronics, the units are controlled by crystals that when compressed produce a voltage. if this is the case then i think it would be possible to wire something to the sensor that would blink when a certain voltage is reached which would in turn tel us if there is knock occuring, it could possibly tell us how often, but not how severe the knock. i will research it more and then see if it is possible
lates
james

I've tried monitorign the voltage from the knock sensor with a couple of devices, both analog and digital. doesn't work on our cars.

A.D.P.
"...If you do too much, people become dependant. If you do to little, people loose hope. If you do it right, people won't be sure you've done anything at all."
bring it on............

I'm sure there has to be an aftermarket knock sensor out there that uses variable voltage outputs..anyone know??

Has anyone tried this product?

http://www.msdignition.com/1protool.htm#anchor168229




Eric Madden

sounds very interesting. any prices?

the voltages that the knock sensor on our car would output would be in te range of millivolts or less. i was thinking of producing a circuit that amplified the signal or used the signal to switch a transistor to trigger the LED to light. we definitely could not drive the LED directly from the knock sensor wires.
lates
james

ill be your other prototype guy james, ill pay u etc...i was looking into the msd knock alert what do u all think? so hows the car james? done with the rebuild ?

Michael 99gs
Mods:
Hrc Stage 2
S-FMU
315cc injectors
Crane HI-6DI2
Greddy Type S Bov
VC-2
Road Race Catch Can
Greddy Profec B & Switch
Apexi WS Catback
Super Afc
Autometer Boost,
Egt,Tranny Temp Gauge & Cooler
Air/Fuel Light & Digital
Tokico Adjust Struts
Eibach Pro Kit Springs
Front & Rear Upper Bar
CarCraft Interior
Sound System= Bring it On

Dude, I have had an msd knock alert for like the past 6 months. I'm pretty sure I posted abotu it before, so it shoudl still be in the search.

A.D.P.
"...If you do too much, people become dependant. If you do to little, people loose hope. If you do it right, people won't be sure you've done anything at all."
bring it on............

James,

Anymore thoughts or work on the knock alert?



Eric Madden

well, i talked to one of the electrical design engineers here and he informet me that a simple circuit can be made to take the millivoltage signal from the knock sensor and use that to control a transistor which would in turn switch power to an external led. The problem i have come to now is that i do not know the resonant characteristics of the knock sensor in our car. if i could find some type of technical data sheet for our knock sensor that would help immensely. Basically it is the same principal as the msd unit, but honestly the parts to fabricate this would cost like 10 bucks only. if i find out more i'll let you know.
lates
James

I think Armond has played around with that MSD knock detector, dunno how it turned out, but I remember seeing a pic of it where the ashtray used to be.