Knock knock, anyone home?

[dggt6]

Hello Guys,
having a bit of a problem setting up my knock sensor.
I have a 3.57 MS setup with a knock input done in the "factory". I have a 2 wire bosch type sensor that does generate AC voltage when "knocked". I have the signal wire connected to the first pin and the second wire connected to the second/earth pin of the module.
I have wired up a new GM knock module as per the MS manuals using 4 out of the 5 pins.
If I knock the sensor, I get a "reading" between the 2 sensor wires but I can not see any reading or movement from the wire going to the MS unit.
What measurement does the MS expect to see from the Knock module?
I am guessing that Tunerstudio should be set to analogue for this type of sensor????

Many thanks for any assistance,
Regards,
Doug

[hybrid]

MS2 can only do a digital signal (on/off) from what I understand.
So when the Knock wire is grounded, the MS assumes a knock and will do whatever is configured to be done on knock signal.

[dggt6]

Thanks Hybrid,
I changed the settings back to On/Off but I am still not getting any "response" from the MS when I knock/tap the sensor. I have an ADC7 gauge that just sits at 1023, a PortAD7 indicator that does not change and the Knock Retard gauge that does not move either.
I think I am expecting the voltage of about 11V at the 3rd module pin to drop to zero volts whenever a knock is detected. Should I be able to see the voltage drop with a normal DMM?
Does this sound correct to you?

Many thanks,
Doug

[hybrid]

Sorry, after reading the manual, it looks like I'm mistaken.
It can do analogue or on/off, but if you're using that GM sensor that's in the manual, then you should be set to on/off.

While it's set to on/off, try grounding the knock wire to your MS.
If the knock indicator does not light up in TunerStudio, then something is wrong with the MS knock input.

[prof315]

A GM knock module will work best with a GM knock sensor. Your best bet is to find a GM sensor from an engine with the same or close to the same cylinder bore as yours. Knock frequency is largely related to bore diameter and GM sensors are "narrow band" in that they only work in a narrow frequency range. The Bosch sensor is a "wideband" sensor that will work best with a tunable knock controller like KnockSense or the MS3 knock module.

[dggt6]

Thanks Prof,
my engine is a 1970s Triumph 2500cc 6 cylinder with a 74.7mm bore. Any suggestions where to start looking for a compatible GM bore size?

Hybrid,,
reset Tunerstudio to On/Off and disconnected the MS wire from the module. Last time I tried this, the ADC7 gauge dropped from 1023 down to about 500 and the PortAD7 indicator did NOT change.
This time, removing the MS wire caused the ADC7 gauge to drop down to fluctuating between 0 and 1 and the indicator changed colour!! Touching the MS wire to earth stopped the ADC7 gauge fluctuating and held it still at 0. I also noticed that the Knock Retard Gauge did NOT move. I have lowered the settings down to 0RPM.
I can assume from this that my MS2 is setup to read a signal correctly?
Somehow, the module doesn't seem to be "triggering" a zero V signal. Are there different types of these GM modules I wonder?
Any further thoughts?? (please)

Thanks,
Doug

[hybrid]

I don't know anything about the GM modules sorry.
I'm using KnockSenseMS:
http://viatrack.ca/

It's designed to work with Megasquirt.

Is the engine running yet? You might not see any REAL knock changes unless the engine is actually running.

[pmbrunelle]

I did some digging into the GM knock sensor + module topic:
http://www.fiero.nl/forum/Forum2/HTML/139346.html

Anyway, I have made a list of GM-style knock sensors. I suggest you find which engine(s) is associated with each knock sensor. From there, you may find an engine having a bore size similar to yours...

But 74.7 mm is an awfully small bore... so rather than putzing around with GM stuff that doesn't quite fit, I would suggest you stick with a non-resonant one-size-fits-all sensor.

[hybrid]

But 74.7 mm is an awfully small bore... so rather than putzing around with GM stuff that doesn't quite fit, I would suggest you stick with a non-resonant one-size-fits-all sensor.

Or talk to viatrack who ask for your engine configuration when building the unit.

[dggt6]

Many thanks Gents,
I will go and get one of them 1 wire GM sensors and give it a crack.
Thanks again for the help and interesting article links.

Cheers,
Doug

[dggt6]

Hi Guys,
well I got me one of those them 1 wired knock sensors and it aint done me no good.
I got 2 (second hand) sensors to be sure and they both give out a few more millivolt than the bosch 2 wire sensors.
I think I tried every combination of the settings in TS with no result.

Does anyone know what the GM type module is expecting to receive or what it needs before it "switches on"?
By a similar token, does anyone know what a MS2 is looking for to trigger some knock retard? Zero volts? It is seeing 9.95v at the moment from the "3rd" pin.


Many thanks,
Doug

[tryingbe]

does anyone know what a MS2 is looking for to trigger some knock retard?

It depends on the knock moduleno MS2, with an On/Off switch, you set MS2 to what to look for. KnockSenseMS puts out 5 volt when it is normal, and 0 volt when it detects knock.

It is seeing 9.95v at the moment from the "3rd" pin.

You need to wire it up correctly by adding resister and diode.

http://megasquirt.free.fr/sources/MS/ma ... /knock.htm

[dggt6]

Thanks Tryingbe,
you may have found my problem!
I went back and checked my records of when DIYAutotune made the unit and added the knock sensor input. They said they had set up my MS with a Knocksense specific input. I was thinking it was a "generic" input that would work with the GM Module.
So you think I need to modify my MS to as per diagram...

proto_knock.gif (13.5 KiB) Viewed 752 times

Many thanks for sorting this out for me
Cheers,
Doug