I am still using Location 3.

Although being completely happy with Location 3, I still plan to put some rubber under the piezo to dampen the vibration even more just to test the limits.

I will use the rubber because there is no where else on the engine that has less vibration. I say this based on using my hand to touch areas on the engine as the engine is idling in Park. The valve cover (Location 3) had the least vibration.


It is extremely hard, at least for me, to determine if the ecu is pulling back the timing by reviewing the data logging. The normal timing (without having knock retard) jumps all over the place as normal practice. So without knowing where the timing should be at that split second, you can't say if it is or isn't experiencing knock retard.

Not truly knowing if I have knock retard has bugged me ever since I started this knock sensor endeavor. The only true way to know is to check the OBD2 Enhanced parameter for Knock Retard. And, most in-car performance loggers, including mine, does not have the ability to show any Enhanced Parameters.

 

@Inaccurate

I never did ask... Are you running stock engine mounts, or aftermarket? I recently purchased a set of XLR8 mounts and am thinking that I'll need to relocate the piezo sensor to somewhere on the chassis instead because of the increased vibration. Any thoughts on that?

 

All three mounts are Innovative 75A.

I did try mounting to the chassis. With the engine idling in Park, I felt along the engine bay (chassis) for a spot that had the most vibration. The pic above shows the spot that I tried. Failed. CEL. Not enough vibration.

Since we are discussing mounting the piezo, please be careful with the valve cover location. The Location 3 (valve cover) is not a Ground source. The valve cover has a rubber seal and each bolt has a rubber seal. Thus, the valve cover is not in direct contact with the aluminum head and has no path to ground.

Previously, I was using a pigtail wire for the piezo ground. The pigtail was just 3 inches with an eyelet on the end. I would ground the piezo on the piezo's mounting bolt. But for the Location 3, I had to extend the wire to a good ground source.

 

Good to note. When I built my piezo sensor, I added 2 grounds. One on the bracket itself and one at the end of the wire.



P.S. I really can't say it enough. Thanks for sharing your wealth of knowledge with us! My current setup wouldn't be possible without it.

 

Excellent idea. I like this plan.

Just as a side note for other readers - The J&S unit is only able to retard the timing, not to advance the timing. However, the oem timing map (without any Knock Retard) is advanced as far as you would want it. So, there is not really any need for being able to advance the timing.

 

Thanks to the both of you. I'll be the next in line to do this. I've got IM 85a's so I hope I don't have problems with location 3. I sure wish there was a way to get the enhanced knock data with the lower priced dataloggers.

 

bmeyer,

With your bracket being angled, this will reduce the vibration felt by the piezo. The vibration force vector when mounted to the valve cover is perpendicular to the valve cover.

Not that this is bad. I think that the piezo can tolerate even less vibration than Location 3. I just want to point out this difference between your setup and mine. I might even try an angle bracket too because I am wanting to reduce the vibration even more until I find the lower threshold of vibration... but still leaving it in Location 3.

 

I wouldn't worry about this too much. It would just cause you some inconvenience in having to try some different mounting locations. With each location that you try, you must do a battery disconnect to reset the ecu. This is the only inconvenience .

Some trail and error might be needed, but your mounts will not prevent you from using the piezo.

 

bmeyer and KN_TL,

Thank you for the kind words of appreciation.

 

Sorry to bring back an old thread but I thought this would be the best place to ask.

With the J&R ecu coming out soon, I started looking into what it takes to connect a knock sensor to the MS2-EXT.

The manual mentions GM sensors and GM ESC as a typical setup.

Does anyone know if the stock sensor would be compatible with a GM ESC for this setup?

Also, in further reading, the frequency (tone) of the knock is sometimes part of the equation, but I can't find anything about who uses this method or if it is needed in our case. Does anyone have any idea with this?

 

Old thread ?????

This is a current thread.... it just doesn't see much traffic.

KN, I do have some input on this topic. Short on time now. Look for my reply later tonight.

 

The Acura oem knock sensor can not work with the GM ESC. Why? Because this whole business on detecting engine knock is a tricky business. It is more of an art than a science (see my rambling below for my explanation).

Different brands (or even models from same brand) are not interchangeable. A knock sensor produces a unique output per each brand/model of sensor. As such, there must be a micro-processor specifically programmed for each specific brand/model of sensor.

A Brand X sensor produces a different output pattern than Brand Y. The micro-processor made for the Brand X sensor would produce erroneous results if the micro-processor was feed the output from the Brand Y sensor.

To see how each brand/model of sensor can vary from each other, see this enlightening link (click here). This link show the output waveform from various sensor brands. It is easy to see just how much difference the waveform is between brands.


ADDITIONAL RAMBLING BELOW (Optional)

A knock sensor produces a very low voltage signal that is erratic and crude in nature. The most important component of any Knock Monitor is the micro-processor in the control box. The crude output signal from the sensor is processed by the micro-processor based on that company's programming. This is why a Knock Monitor from Brand X will perform drastically different than Brand Y, although both brands use the identical Bosch Wideband Knock Sensor. It is a very difficult task, programming wise, to distinguish between background vibration and true detonation ringing.

Although any knock sensor is biased to a certain frequency range, closest to that of detonation ringing, this does not mean that the sensor is not also picking-up background vibration in that same frequency. Detonation ringing does not have an exclusive frequency range that is free of other stuff. Other stuff does emit vibration is the same frequency as the detonation ringing. It is the job of the micro-processor to use advanced logic to discern the difference. Even the best Knock Monitors are not able to truly filter-out the background vibration. The most that can be hoped for is to reduce the background stuff as much as possible while highlighting the detonation ringing. For example, this is why my Phormula produces a reading of 35% even though I have no detonation. The 35% is the background noise that could only be filter-out to that extent. And, Phormula is one of the best units available.

And as a side note - The frequency of detonation ringing is determined by the engine bore diameter. Most Knock Monitors have a configurable setting so that you can set the exact frequency for your bore size.

 

I spent a little time on the MegaSquirt website. I see no specific mention of knock detection for the MS3. So, If we assume that the MS3 has the same knock abilities as the MS1, then the following might be fruitful.

The manual for the MS1 states (click here) -

In short, the MS1 is NOT a knock monitor. However, the MS1 can accept the output (0-5 Volts) from a dedicated Knock Monitor.

And, the Phormula KS-4 (click here) does have this feature -


So, perhaps it is as easy as purchasing a Phormula KS-4 (one of the best Knock Monitors on the market) and wire it into the MS3. I recommend calling MegaSquirt to inquire.

Wishing you luck and please keep us updated on your findings.

 

Thanks Inacc. I'm now educated on knock sensors and detectors. It all makes total sense to me.

Also answers my question on the frequency. I read what you posted but reading it again made more sense (I have an issue with having to read things several times).

I was thinking of going as cheap as possible, but now thinking otherwise.

I am now going to have to have an internal debate on spending $359 for the Phormula or a couple hundred more on a J&S and have the ability to control each cylinder.......