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Old 09-16-2008, 07:21 AM
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Default knock sensor help

i need some help from yall tuning gurus... i posted awhile back asking about my knock sensors being possibly set off by the heads and cam install i did. ive tried clearing the codes at advance auto but they just come right back on and they must be pulling some major timing cause i got beat by my girlfriends bone stock ss. thats when i finally decided to change them. so i guess what im trying to ask is when i change the knock sensors and check the harness too, and the codes go away will my car go back to the timing in my tune or will it need to be retuned?
Old 09-16-2008, 08:50 AM
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you will probably have to mess with the Knock/detonation thresholds in the TUNE, if your car is fairly new, which I see it is an 02' then I bet your knock sensors are fine.


when I did my cam swap, due to my specific cam I had to mess with my misfire tables thresholds.

Get your tuner to get your car right.
Old 09-16-2008, 02:19 PM
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When I asked my tuner about it he said they probably messed em up when they put the intake manifold on and just to put new ones in and see if that fixes it but I don't really wana pay to put new sensors in if that's not guna fix it that's y I'm trying to see if anyones had this problem or if they just knew what to do thanks for any help guys
Old 09-23-2008, 06:31 PM
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Need HELP!!! Zl1killa is probably right but I just changed my knock sensors and checked the wires they were good but the code keeps coming on can sumone please help could there be any other reason they would keep coming on?
Old 09-23-2008, 06:50 PM
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Are you getting misfire codes or knock retard?
Old 09-23-2008, 06:58 PM
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If you are getting knock sensor codes, then it is something in the sensors or the wiring - not the tune! If you replaced the sensors, then you need to check over the wiring really good and make sure you didn't pinch it under the intake at some point and cut a wire - that is usually what people do. The other thing is that the knock sensors can't be overtightened or they will be damaged...
Old 09-23-2008, 09:38 PM
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All the wiring is good and I didn't do the install the professionals at the stealership did it also I made sure the y pipe isn't hitting under the car cause I heard that can set them off 2 I doubt it actually can buy I'm trying everything I just don't understand
Old 09-24-2008, 12:17 PM
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ok so i went to advance and the codes are p0327 knock sensor bank 1 low input and p0332 knock sensor bank 2 low input i cant figure it out the sensors are new and the wirring harness looked flawless please help these things are kicking my wallets ***!
Old 09-25-2008, 04:06 PM
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Anyone?
Old 09-25-2008, 04:30 PM
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Originally Posted by 02anti_vnm
ok so i went to advance and the codes are p0327 knock sensor bank 1 low input and p0332 knock sensor bank 2 low input i cant figure it out the sensors are new and the wirring harness looked flawless please help these things are kicking my wallets ***!


Low input can mean bad sensors (not the case because they are new), wiring issues, sensor installation issues, or PCM issues. If the circuit inside the PCM that feeds the sensors goes bad, then a low input will be displayed.
Low input has nothing to do w/ knock. The signal related to the sensor has an issue. Maybe there's fluid in the sensor hole. The only way you're gonna know is to look yourself. Remove the intake, remove the knock sensor connectors & look in the sensor hole. Then remove each sensor & look @ them & the hole they came out of. There should be no thread sealer or teflon on the sensor, this will kill the ground & cause your issue. Then re-check the wiring, all the way into the PCM connector.

My damn wiring schematic doesn't show what the input is. So, just check with a multimeter to see that you are getting a voltage or a current @ the connector that plugs into the knock sensor. Put one lead on the connector & the other lead to the side of the tapped hole that the sensor came out of. The key power must be "on" & car NOT running. Won't run anyway without the intake, but, wanted to note it. If you get power, note what the power is. Also, if you get power, re-install the knock sensors into their holes & do not connect the wires to them. Now check voltage using the knock sensor as the ground. If same power, then re-install the wiring to the knock sensors, then install the intake. Clear the knock sensor codes. Drive the car. If the knock codes come on again, then it is most likely the PCM (all other things checked).
Old 09-30-2008, 10:49 AM
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The "one wire" GM knock sensors have an internal resistor connected between the case and the connector pin. Depending on the part number, the resistor value can be 3.9kΩ, 8.2kΩ, or 100kΩ.

The PCM has a resistor of equal value connected between 5v and the knock input pin. The knock signal then sits at 2.5v.

Your new sensors must have the same value as the original ones.

If the knock signal wire breaks or the connector comes off, the quiescent knock signal would be high (5v). If the wire is pinched and shorts to ground, the knock signal would be low.




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