Bypassing a Knock Sensor (Toyota)

[Careless]

Hi Ghouls and Ghosts.

 

I'm having trouble with two of the Toyota Previas I drive once in a while. I've checked every sensor on the car except for the knock sensor, and the knock sensors on Toyotas have been known to trip the ignition retard function without tripping the CEL/MIL light (check engine/malfunction indicator light, for those still asleep). I have access to 3 previa. Two that are on the road are doing the same thing, and the one that isnt on the road is actually in better RUNNING condition, and we've swapped all the possible sensors to both, and they cut out at 2000 rpm with ignition retard triggering.

 

So... I can't find a damn service manual for this guy. But I'd imagine a Camry knock sensor is the same for the 1993 year.

 

What I'm wondering is whether or not I should do the following:

 

1) use a piezoelectric transducer to mimic the frequency of the engine and hook it up to the voltage wire from the ECU as well as the speaker wire, thereby re-routing the knock sensing wire from the ECU to the piezoelectric element to fool the ECU into running static timing.

 

I've read about this working on Hondas.

 

2) Install a variable rotary potentiometer after figuring out what the knock-trigger value in resistance is, and wiring in the potentiometer with a range that covers the trigger value at around the top end, so I can adjust for the lower resistance.

 

 

 

My trouble is figuring out which method would work best because I'm not sure if the knock sensor is resistance based, or voltage based.

 

 

can someone flick on the flood lights, here?