I'm gonna do this tonight in preparation for dyno tuning tomorrow. I know the circuit can be found here: http://www.bfranker.badz28.com/fbody/guides.htm

It lists 2 different circuits, but only one of them (the first) is valid. Before I do it, does anyone know what the other option was?

Also, is it worthwhile to do this or can it just be masked/disabled in the PCM?

 

I did away with the desensitizer circuit I had on my own car. I now run with an LT4 Knock Module (you won't have time for one of those before tomorrow though!) and a complete bypass circuit! To bypass it, hook a toggle switch (SPDT) so on the common contact goes to the PCM. One of the other contacts goes to the knock sensor (normal alignment) and the other contact goes to a 3.9k ohm resistor which is connected to ground. To bypass the knock sensor simply throw the toggle to the 3.9k ohm resistor side and no more knock sensor. Just be careful because you have no protection like this from your knock sensor!

This only works on OBDI cars BTW

Picture...
http://www.bfranker.badz28.com/94z/KSswitch.JPG

 

That desensitize circuit never worked on my car.

Max knock retard = 0 did though.

 

Ha! I actually have an LT4 knock module in the cabinet from way back when...I'll throw it back in. The circuit you describe is exactly what we wired up on my buddies car years ago and it works great, so I'll do the same. Thanks!

 

I would NOT recommend deleting the knock sensor on a supercharged+nitrous car.

I have a small program somewhere on my comp called "knockit.exe" that I used for mine. Just plug in what percentage you want the circuit desensitized and it gives you the resistor values.

If you are set on disabling it though, you might as well do as gogo said. Max retard=0.
I did that when I would run motor with no problems.

 

Is the LT4 KM really worth it then...from the looks of it you guys are still detecting false knock and that's why your going to the lengths to be able to bypass it?????
-b

 

Link to knockit.exe
http://www.charm.net/~mchaney/f-tech.htm
I tried the 100% desensitizing today. I get 0.06 retard afterwards. I guess that's close enough to 0. It throws a code for low KS voltage though. I think I'll play with some other resistor cominations.

 

I realize this is pretty old, but I have a question. I have a MADZ28 OBD1 conversion, which still uses the OBD2 sensor which measures 100kohm. So in place of the 3.9kohm resistor, I would use a 100kohm resistor because its an OBD1 computer that has been modified to accept the OBD2 knock sensor, correct?

Chris

 

I have the same question, did you ever get an answer?

 

It seems to work, but I have other issues right now so I can't confirm for 100% My reason for putting it on was due to getting about 2-3* KR with the cutout open vs. 0* when it was closed. Now with the switch set to bypass the knock sensor, I haven't seen any KR on Datamaster, but the valvesprings are floating so I haven't really done too much WOT logging. More will come this spring, since I am putting on a Super Vic / New cam / 918 Beehives.

 

Awsome, i guess i will throw the 100k resistor in and hope it works.