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jdhill 02-10-2017 12:46 PM

M110 knock sensor.
That's the plan, my 75 is too early to have one and I want it in place befor going Turbo. Any photo's of the sensor location on the M103/104 would be much appreciated or any tips as to where to place it on an inline 6. Thanks.

duxthe1 02-10-2017 04:17 PM

I don't have any pics but the engines so equipped have the sensors under the intake manifold, in the block, up in the cylinder bore area by cyls 2 and 4.

97 SL320 02-10-2017 05:37 PM

The M104 has 2 sensors.

It is more complicated than just bolting on a couple of random sensors. The sensors are piezo electric microphones tuned to specific frequencies so every engine family is going to have a different frequency, sensor location.

The sensor needs to be physically mounted to the block in such a way that it does not vibrate. US engines tended to remove a block coolant drain plug and screw the sensor in there.

Someone has to of tested various sensors by now, it is just a subject that hasn't come up very often.

Try here

I think this is the original site
Welcome to diy_efi/efi332

This might be a different site

jdhill 02-11-2017 12:11 PM


jdhill 02-11-2017 06:40 PM


Originally Posted by duxthe1 (Post 3682062)
I don't have any pics but the engines so equipped have the sensors under the intake manifold, in the block, up in the cylinder bore area by cyls 2 and 4.

A bit of thinking out loud if I may. I also am using an MSII, extra, for my ECU.
Did your M103 have knock sensors and did you connect them to the MS?? Found the K/S for the M104, a dual sensor unit that apparently has two separate circuits. It looks like I could add two input circuits to the MS but Tuner Studio
only allocates one pin for input. Does the M104 combine the two circuits into one?? Any info like a wiring diagram for the M104 sensors would be much appreciated. Thanks

97 SL320 02-12-2017 04:58 PM

The M104 runs each knock sensor into the ECU, they are not wired together.

Have a look at this add on to a MS3, no idea if there is a stand alone unit. ( Also look at MSD as they have lots of ignition stuff ) :

Product Description

This add on board solders on top of the MS3 daughter board and gives you two channels of knock input that the MS3 can use to retard spark. Using this module will give you a much more sophisticated knock detection circuit than on any previous MegaSquirt knock detection. Features include a programmable bandpass filter, levels that change with RPM, the ability to assign different cylinders to different sensors, and different gain levels for each cylinder. See the MS3 manual for details.

We carried out our own testing with a Bosch 0 261 231 008 sensor – this is a broadband (non-resonant) sensor type that has no built in filtering, so it can be used with a wide variety of bore sizes. Similar Bosch sensors should also work (most of these only differ in their packaging). This knock module can also be used with tuned knock sensors if they are tuned to your engine’s bore size.

This board only works with MS3.

Note: If you are ordering the knock module with an assembled MS3, we can install it in the MS3 for an extra $15 charge. Please make a note of this in the Comments field when you place the order, or this will be shipped as a separate part. However, if you need an assembled MS3 with knock module installed, you may also want to consider the MS3-Pro, as this includes the knock conditioner and real time clock circuit as standard equipment.

jdhill 02-12-2017 05:52 PM

Thanks for responding, I have a query in now at DIY as to how do you program 2 sensor channels in Tuner Studio when you can only assign one input pin. Is the added board permanently programmed, how much retard, when etc.??
Mark at DIY has been a real help with other questions I had.

97 SL320 02-12-2017 06:02 PM

I have not used this board however it states that it adds 2 channels of knock input.

duxthe1 02-12-2017 10:55 PM


Originally Posted by jdhill (Post 3682349)
Did your M103 have knock sensors and did you connect them to the MS??

The 103s don't come with knock sensors, though the bosses to mount them are in the block. The 104.980 is the first engine to use them and it literally uses a 103 block. I don't use a knock sensor in my setup. These engines are pretty damn tough. I just tuned it up to the ragged edge and backed off a bit. It cant live forever at the edge but a little rattling to find the limit wont hurt it.

jdhill 02-13-2017 06:46 PM

As always, DIY autotune came up with the answer. You need MS3 to use 2 knock sensors and a JSM card.
Megasquirt3_TunerStudio_MS_Lite_Reference-1.5 page 153
Think I'll skip the sensor for now, not building a race engine.

97 SL320 02-14-2017 06:54 PM

Have a look at this thread Who make the best Knock sensor? • Speed Talk and also search for more info ( Speed Talk is a very serious engine builder site ) the last poster is David Redszus, Who We Are unless he has posted more recent info, I'd tend to listen to his post.

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