Hello,

Im planning on using a bosch ksp-4 knock sensor with my megasquirt interface, since im using a 1 cylinder engine i dont worry about the placemant, since there is a pre determined spot. The problem i have is how do i wire it with the megasquirt . Since the megasquirt says you should rewire some stuff on the board. #ad

Like in this picture, but somewhere else it says you need an external ms.

I hope you guys can help me.

Kind regards,
Rick

 

Ms2? I'm using a knocksense board with ms2. Not impressed with the results so far. Unusable as delivered shows knock all the time. I've added a 10k resistor with little change. Mine is the factory sensor/location for the engine.
Another member on here is using j&s with megasquirt I believe. Should turn up with a search.

 

I'm using a MS2 with the GM knock sensor and module. Its working fantastic with that circuit but built external to the MS. You don't HAVE to build it in the project area, and in this case it was easier for me to build it into the wiring harness going to the knock sensor module.

 

Chaos can you share the circuit you built for your knock sensor?

 

Its the same one posted above.
#ad

Its just inline with the wire. The wire coming off the GM knock sensor module has an inline 1Kohm resistor in the harness right before it goes into my MS. At the MS side of the resistor a Zener diode tees off the resistor to a ground point. Then it goes into my MS on one of the spareadc ports as-is.

 

This is some Khaos up in here haha. That’s why I dislike knock sensors because they show false knock or no knock like the single flip of a coin based on set settings. We need the MadScientist in here.

 

Thanks Kaos I didn't realize you were using the GM module as well. What did you get the module off of?

 

late 80's Corvette or early 90's suburban. It works best if your bore is close to 4 inch. Thats what the GM sensors are tuned for.

 

This is the one I used:

 

Is that what that does!
haha. Ive pulled these off several s-10s. They call them "ignition spark modules". Which is kinda stupid if they are the knock sensor module. IMO, call them what they are.

 

Yes! Thats what they are... Yeah, the name makes you think they're like an HEI module or something. Nope, they're a signal conditioner for the knock sensor.

 

Yeh the s-10s have ignition module in the distrubutor, besides the computer control. So I never knew what the point of it was. Had I cared enough i might have noticed it led to the knock sensor in schematics.

 

Kaos where is the knock sensor located? My engine is a 4" bore. Thanks

 

On most of the Chevy's the sensor comes from its in the coolant gallery drain plug down under the exhaust manifold. Sometimes on both sides, sometimes only on one(drivers I believe). I stuck mine in the same location on my 426.

 

On all the 4.3s Ive seen, its on the bell housing area of the block next to the oil pressure port. But ive seen them down on the side of the block on 350s before.

Ive seen peeps put them back in the head. My understanding is that block rings at a specific frequency that the head will not.

 

Yep, thats my understanding as well. I figured I'd do the install as close to the place it was installed originally since knock sensors can already be a pain.

 

I never got around to installing the knock module in my MS3, but from what I've read it's a much better experience with MS3 than it was with MS2. Miataturbo.net has several threads with detailed setup/configuration info.

 

Yeah, the MS3 has an optional internal tunable knock conditioner. So you don't have to rely on using the GM module, or KnocksenseMS or something like that.

That being said the MS2 one works just fine if you understand it's limitations and set the sensor up right.

 

Ms2 is just on or off if you want to retard timing with it. You can log the analog signal with one of the inputs but it's not actionable. Do I have that right?
Is the ms3 the same? I've got an ms3x for a ls in a Isuzu pup but it's backburnered for now.

 

No, the MS2 can do fully actionable analog sensors too. You just need an external conditioner that supports it. The GM one I'm using is an on/off conditioner. You can still do levels of retard even with the on/off sensor, it does so by measuring "knock windows" which are the number of times the knock conditioner triggers in a certain amount of time. You can pull more timing if knock triggers more times in that window and ramp it off as you go longer without knock.

The biggest difference in the knock detection between the MS2 and MS3 is that the MS3 supports an optional INTERNAL knock conditioner so you could connect the sensor directly to the MS3 without an external conditioner and let it deal with the sensor's signal directly. Theoretically this will let you tune your own harmonic window for bore size, and filter noise a bit more effectively. In practice I don't know if its all that much better. I wouldn't buy an MS3 over an MS2 *JUST* for that feature. But if the other upgrades on the MS3 already make sense, its a great addition.