Torquing knock sensors on 1990 Q45 (Q45tech)

[mattd1979]

I need to know what will happen if the knock sensor is not tightened enough and what will happen if it is over tightened. I have 2 torque wrenches. One is a fan gauge style and the other is a clicker. The problem is that if I torque the knock sensor to 12 ft-lbs with the clicker and then go behind it with the fan style torque wrench, I will end up turning it more which concerns me. I don't want to over or under tighten the bolt that secures the knock sensors. Please let me know something specifically Q45tech as I think he wrote an article on this but I can't find it. I want to get the car back together but this is holding me up.

MattJacksonville, FL

[Q45tech]

It wouldn't be concerned as to the exact amount [give or take 25%].The Nissan knock sensor is just a conventional microphone unlike other brands which have a tuned mass microphone.

The audio frequency band pass filter is inside ecu and there is AGC [automatic gain control] in ecu.

[mattd1979]

Then what about the different readings from two different torque wrenches. Do you think that has long as they both are snug then they will be fine? If so then that will take a load off of my mind.

[InsanityInc]

It's not a microphone, it's a piezoelectric device.

[Q45tech]

Obviously you didn't know that many low cost microphone use the "piezo electric effect". Piezo units have some of the highest vibration sensitivity of all microphone types.

Connect the KS to an audio amplfier and speak near it.........if it acts like a microphone it is a microphone. Don't confuse the MASS of a diaphram this just shapes the frequency response of such a microphone.

http://zone.ni.com/devzone/con...CBF0D

"All of the sounds on this page were recorded with a cassette recorder, by connecting the microphone input into the knock sensor wire at the ECU. I have a 100K resistor and a 0.1uF capacitor in series to prevent the cassette recorder from influencing the signal that the ECU sees. (Click here for more details.) I then digitize the portions of interest on my PC, using the standard Microsoft Sound Recorder"above from:http://home.netcom.com/~bsunda...s.htmh ... an9770.pdf

http://en.wikipedia.org/wiki/Piezoelectricity

[InsanityInc]

Yes, but saying your knock sensor is a microphone is like saying your ingnition coil is a tesla coil.

[IvoryJ30t]

on my A32 maxima, the knock sensor sits under the intake manifold.

i used a 1/4 inch ratchet, and stuck my hand under the intake manifold.

[much easier than R&Ring the mani, or using an assortment of uni's and extensions]

i just got it as tight as i could with the little ratchet. it works fine.

there was a very noticeable improvement in throttle reponse and accel.

there was no code [ecu mode 2, and obd 2 scan] the sensor was just old [10+ years, 94k miles]