knock sensor questions

[dohcfiend]

how do they function? are they powered or do they just send an output signal to the ecm?

lastly, if all they do is send a signal and if say u have a 91-95 ecm system with a 96-97 engine, could u splice the second one in paralell to the other one and they both function correctly?

[pepsi_coke]

http://www.60degreev6.com/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=32&page=1

This sensor is screwed into the block and detects detonation. If knocking or pinging is sensed the ECM will retard the ignition timing to prevent serious engine damage. Depending on the strength of the knock the ECM will pull a set amount of timing very fast and then slowly reduce the knock retard back to 0 or more knock is encountered, whichever happens first.

The circuitry in the knock sensor pulls the +5V input voltage down to 2.5V, the knock sensor then produces an AC voltage that rides the 2.5V DC voltage. A knock will cause a voltage spike in AC voltage that oscillates about the 2.5V bias, if the spike is above 3V it is considered knock.

[dohcfiend]

so in other words probably not. thanx.

[dohcfiend]

last thing. can i pull the wiring back and hook up the front one instead of the rear one and everything still function correctly?

[your_I.D.]

I dont see why not. Are the part # the same?

[Kohburn]

yeah you can use one or the other

if you exhaust routing going out the back then using the front sensor would be benefficial to avoid exhaust related false readings

[dohcfiend]

hmmmmm. very nice. i like. thanx guys.

[dohcfiend]

sorry to bring it back up but i can't believe it. i was f@@king right. i was helping a bud of mine with a lt-1 harness and it had 2 knock sensors and they were wired paralell to 1 wire going to the ecm. YAY

[farmerz24]

so then dual knock sensors. this would explain why i always pop my rear pistons from det. and not the front. i may do this aswwell.

[grandprixgtp_91]

the only problem ive had with using the 96/97 sensors , is you need new connectors and the 91 connectors have resistors in them and the 96/97 ones dont so the ecm sets the knock retartd to max, so with an early style ecm you would need the early stlye knock sensor and connector.

Jake