LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Knock Sensor Desensitization using resistors

Old Oct 7, 2005 | 10:00 AM
  #46  
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Re: Knock Sensor Desensitization using resistors

Originally Posted by jeepramz
If you cut it out completely use 3.9K ohm 1/2W 5% Carbon Film Resistor pk/5 .99 Brand: RadioShack Catalog #: 271-1123 Model: 271-1123
If I knew when I was going to flip the switch I'd be sure to have 93 or more octane gas in it. In the 60s they didn't have fancy computers but the gas was leaded and higher octane than it is now. Just me though.

They would also rattle their *** off if the timing was high or it was hot or ya lugged it around a corner 'cause ya were to lazy to shift gears.
Ya need to run 91-92 octane in these car's anyway. This is not a trick to burn lower octane,it's for performance and how not to have retard cut performance from false knock.
Back then ya didn't have anything false.
Old Oct 7, 2005 | 10:16 AM
  #47  
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Re: Knock Sensor Desensitization using resistors

http://falklands.globat.com/~fullthr...nocksensor.JPG
http://falklands.globat.com/~fullthr...nsorbypass.JPG
Old Oct 7, 2005 | 09:00 PM
  #48  
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Re: Knock Sensor Desensitization using resistors

Thanks for the pics. So that second one, which involves the switch. When the switch is on the ecm will utilize the knock sensor like normal and when its off what is it doing/telling the ecm?

EDIT: I think I get it now, so when its off its sending the 1/2W constant power to the ecm(from the resistor) so it thinks there is no false knock?
I am most likely going to be using the switch method because Id only like to turn the knock module off for racing which isnt too often. Is the KM wire the only blue one coming out of the ecm?

Last edited by Jazsun; Oct 7, 2005 at 09:04 PM.
Old Oct 7, 2005 | 09:07 PM
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Re: Knock Sensor Desensitization using resistors

With it switched to resistor it tricks the computer to think the knock sensor is hooked up. It reports no knock. False nor real. The two resistor deal just desentizes the knock sensor by 25%. So if you get some bad gas you don't destroy your engine.
Old Oct 7, 2005 | 10:05 PM
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Re: Knock Sensor Desensitization using resistors

Originally Posted by jeepramz
With it switched to resistor it tricks the computer to think the knock sensor is hooked up. It reports no knock. False nor real. The two resistor deal just desentizes the knock sensor by 25%. So if you get some bad gas you don't destroy your engine.
Glad somebody had a picture 'cause I don't have a way to get it on the screen.
That is one way. If ya get bad gas with my set up ya just flip the switch- to just as it was from the factory. The other way ya got no knock retard at all.This way there is no wondering if ya got some retard or not and knowing ya got full retard if needed.
Old Oct 7, 2005 | 10:30 PM
  #51  
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Re: Knock Sensor Desensitization using resistors

If I start getting any knock for some reason I'll probably add a switch and do the desentize on one side and the knock sensor delete on the other. Best of both worlds.
Old Oct 7, 2005 | 10:35 PM
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Re: Knock Sensor Desensitization using resistors

Originally Posted by jeepramz
If I start getting any knock for some reason I'll probably add a switch and do the desentize on one side and the knock sensor delete on the other. Best of both worlds.
I think the resistor I use is a either a 4.5K or a 4.7K and it works. It won't hurt it if ya got 92 octane,unless some idiot has the timing jacked up to the moon.
Old Oct 7, 2005 | 10:47 PM
  #53  
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Re: Knock Sensor Desensitization using resistors

Yelp got a custom tune. Have to run at least 92. When I measured the resistance of my knock sensor it was 3.9K.
Old Oct 16, 2005 | 09:52 AM
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Re: Knock Sensor Desensitization using resistors

I am trying to locate which wire is for the knock sensor. There are a bunch of wires on the top which connect to the ECM and on the bottom of the ECM there are a ****load. Is the KM one of the wires which connects to the top and is blue? I hava 93 remember.
Old Oct 16, 2005 | 12:00 PM
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Re: Knock Sensor Desensitization using resistors

I have obd2 96 z can someone tell me what resistors to use for my 96?
Old Oct 16, 2005 | 05:22 PM
  #56  
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Re: Knock Sensor Desensitization using resistors

Jazsun:

93 wiring diagram shows the knock sensor connected to pin C8 with a dark blue wire.

80TA:

Measure your stock sensor. I think its around 100Kohms. But you need to verify that.
Old Oct 21, 2005 | 09:52 AM
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Re: Knock Sensor Desensitization using resistors

Originally Posted by Injuneer
Jazsun:

93 wiring diagram shows the knock sensor connected to pin C8 with a dark blue wire.

80TA:

Measure your stock sensor. I think its around 100Kohms. But you need to verify that.
Oh ok, I will look in my hanes manual. Thanks. Do you know if it is one of the wires on the top of the ECM and or on the bottom of the ECM w/ like 300 other wires.
Old Oct 21, 2005 | 10:53 AM
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Re: Knock Sensor Desensitization using resistors

So what are some common sources of false knock?

I am getting really frustrated with this, but I don't yet want to throw a resistor in. The knock may actually be legitimate. I noticed some valvetrain noise on the driver's bank. Would that give me 7* (max) knock retard at WOT?
Old Oct 21, 2005 | 11:31 AM
  #59  
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Re: Knock Sensor Desensitization using resistors

Originally Posted by Jazsun
Oh ok, I will look in my hanes manual. Thanks. Do you know if it is one of the wires on the top of the ECM and or on the bottom of the ECM w/ like 300 other wires.
Top of ECM. It is dark blue. Follow it from the knock sensor.
Old Oct 21, 2005 | 11:32 AM
  #60  
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Re: Knock Sensor Desensitization using resistors

Originally Posted by Kurt Crosbie
So what are some common sources of false knock?

I am getting really frustrated with this, but I don't yet want to throw a resistor in. The knock may actually be legitimate. I noticed some valvetrain noise on the driver's bank. Would that give me 7* (max) knock retard at WOT?
I've got a lifter that pecks alittle. I believe that was doing it. I was getting 7 and 8 sometimes.

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