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Discussion Starter · #1 ·
The knock sensor is installed in our trucks. It appears to be wired up and there is circuitry in the computer to use it. It is turned off by Ford as it has trouble distinguishing other noises and vibrations from the blower or whatever and pulls timing even when it isn't needed. Is this true?

If so, then the computer has the capability to use a knock sensor if the sensor could be trusted, right? There is a prominent company that has a unit that could go between the factory knock sensor and the computer and filter the messages and determine whether it is detonation or not and then when it is that is passed onto the computer to allow it to handle the issue. Since the main problem is in trusting the sensor, if this can make the sensor "trustworthy" then it should be a viable alternative. This system has the ability to only retard a single cylinder or cylinders that are having a problem. There isn't a sudden cutting of all power or a big delay to get it back, it is virtually instantaneous. But for it to work the circuitry must be able to be turned on in the computer through software, which I believe is available.

Any thoughts? Oh he is working on an 8 coil on plug system but he already has a simpler (and maybe less expensive) solution if the above is true.

Jody


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GREAT POST JODY :smt023
I've wondered this myself and still CAN NOT believe SOMEONE doesn't make SOMETHING to make this work.

As you say the technoligy is already built into the L, but Ford chooses not
to use it because of the prob it has
seperating normal Eng Noise, VS Detonation.

Do you know of such a Company ?

My question has always been, WHY CANT WE HAVE A SYSTEM THAT SELF ADJUST'S ITSELF TO A DANGEROUS SITUATION ???
With all the technoligy, all the sensors, this knock sensor, and the Computer, Why cant the Motor sense
trouble BEFORE a rod pops, and go into a Limp Mode
OR SOMETING ?

I'm sure interested if you know something ?
 

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Discussion Starter · #3 ·
Yes Rob, there is a company working on a kit for our trucks as we speak. They are the leader as far as I know in the knock systems, MANY dyno shops use their system. But when I was talking to him he asked about the factory ECU and if it could be turned on. It appears so as there is a place to do it in my SCT Pro Racer software. If that's true then he'd rather use an existing system he has which would be an easier install and probably less expensive. I'll let you know as soon as I know for sure, he just asked me to verify if the wiring and operation is in place on our trucks and simply shut off.

Jody
 

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Discussion Starter · #4 ·
Just to add, this system works faster than imagineable, and only pulls timing from the cylinder that needs it, from one to all eight. Super smooth, and I can't imagine any Lightning owner not being interested as this is the most common way to blow these engines up. Price of course will decide if it's worth it and how many they sell.

Jody
 

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A good knock sensor can be your best friend. Heck, I have an audible alarm hooked up to mine in my Buick GN, as well as a knock sensor gauge. I couldn't believe it when I found out the one in the L was turned off.
 

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Good research Jody, sounds like someone is finally on to something. I always did find it hard to believe that there "was no knock sensor" on the Lightning, and if it is true that it is computer disabled, it shouldn't be anything to turn it on, the question then becomes if it affects any other sensor readings or computer parameters which might throw the computer off...not sure. Sounds like the filter idea is solid though, a noise filter shouldn't be too much, as long as the computer will still recognize the right sequence or sound...

Keep us updated, sounds very promising. And you are right, I don't think there is an L owner around that wouldn't want that piece of mind...

Charlie
 

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I will try my best to explain it and if I am wrong someone please correct me.

The knock sensor is a Piezo electric device that when stressed will output a voltage.

How it works:

Basically, when a ping or pre-ignition happens it creates a shockwave, or you could actually call it a frequency signal. The knock sensor will feel this shockwave or frequency wave and then depending on how strong the shockwave or frequency is the knock sensor will put out a voltage, which is usually somewhere around +/- 2 volts.

What’s important to note is the designers of the motor are going to know approx. what shockwave window or frequency window needs to be sensed by the knock sensor for it to work properly.

For arguments sake lets say when per-ignition happens it creates a frequency of 60 – 80hz. If that were the case then “anything” on the motor that creates that frequency will set off the knock sensor and retard the timing.

I have heard the reason our particular motors do not use knock sensors is because of the vibration of the blower, or the frequency that vibration creates.

So, if our motors put out a frequency of 60 – 80hz (again I have no idea what it is but just using these numbers for explanation) when pre-ignition happens then you can not have anything on the motor that puts out a frequency any greater then 60hz or the knock sensor will retard timing.

The knock sensor is a stupid device that has no idea what created the frequency, it just senses any frequency. This is why you can test to see if a knock sensor is working by lightly tapping the motor with a hammer while monitoring the timing. If the timing retards as you tap the motor with a hammer the knock sensor is working.

Now, lets assume our blowers put out a frequency of 80hz or greater. If that were true it would always activate the knock sensor. This is why I believe what I had read a few years back that our blowers create too much vibration to enable us to use the knock sensors.

You also have to remember that a knock sensor, if working correctly, is going to detect any pre-ignition before the human ear can hear it. So in other words the particular vibration threshold for the knock sensor to work is most likely not going to be felt by your hand and this is why it may be hard for people to understand how the blower could vibrate. It does, its going to have air turbulence vibration (frequency) as well as vibration (frequency) of the rotating mass from the rotors.



Just something I have thought about before, maybe really naïve but anyhow…

I would think a better way of preventing pre-ignition would be to somehow monitor each individual cylinder temperature. The engines susceptibility to knock will vary as a function of fuel octane, chamber design, and other factors but in any regards I would think keeping things consistent you could come up with a safe threshold for our motors running an octane range of whatever, say 90 – 94.

If it were possible to come up with a max temperature for safety, for example 1000 degrees you could monitor each cylinder for a max temperature of 1000 degrees. Anything over that temperature would be considered unsafe and real possibility of pre-ignition occurring.

You could then either retard timing to that cylinder, not fire the next time around to air cool the cylinder, or maybe a longer duration of the fuel injector to put more fuel to the cylinder to cool it down.

You could almost look at it like a thermostat control for each cylinder. You could have a tuner tune, program your motor to react appropriately for your situation. Maybe someone can run a higher temperature before pre-ignition. You could also tune, or program what corrective action to take in the event a cylinder surpasses the desired temperature threshold.

I don’t know, maybe not the best idea but I think, if it were possible, a much better and more precise way of controlling pre-ignition and a great safety device. Worse case scenario is if cylinder temperatures are not reacting to the corrective actions then the motor goes into safe mode, firing every other cylinder like when the computer senses the motor over heating.
 

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Not only would a system like I described eliminate pre-ignition it could also save a motor if it is not getting enough fuel because of a clogged fuel filter, fuel pump not working or what ever reason. Since a lean condition occurs when there is not enough fuel it will create more heat in the cylinder so if you’re already monitoring temperatures you could set a threshold that protects the weakest link.

Just think if the system protected the motor against a lean condition you could use Nitrous with out having to ever worry about a problem…

If I had the cash I would seriously dive into this development…
 

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Sonic:

What you say is very informative and makes quite a bit of sense. Again I am no expert so it is hard to judge one way or the other. My question is why wouldn't the know sensor work if the supercharger was at a frequency of 80Hz or higher? I know this is a hypothetical, but if that is beyond the sensor's range wouldn't it ignore since it can't read it? And if this were not the case, wouldn't this be the reason to have the filter on the sensor to dial in the correct frequency range for the sensor to actually work.

And I believe what you said to be true, it does make sense. I think the thing is knowing what vibrational frequency all the doo-dads under the hood make is going to be the real problem. I am going to take a guess and say that the frequency range for the knock sensor is probably in the range of the cavitation noise of the supercharger, which is why it is disabled because it would pull timing every time you hit boost.

I like your idea, but that is a lot of technology and it will be expensive to develop. It would probably work the best because you are monitoring actual combustion conditions, but that would be an extremely difficult task to have 8 sensors with wiring, and wire them to retard differently under different situations. You would need a separate computer brain for it, or find a way for the tuner's to write some code to make use of that. That is why the sensor is nice (if it worked for us!!) It is low tech and does the job in a round about way.

Trust me I am not knocking your idea, I think it is great. If you do come up with something, please let us know. I like the way you are thinking!!

Keep up the ideas all!

Charlie
 

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Your right, if you can find something that is dialed in it may work. I guess what I was trying to show as an example, and I have NO idea if the frequency range is the same between the blower vibration and pre-ignition vibration, but usually you will have something that can sense a particular range.

Let’s say that range is 60hz – 80hz which would be a very tight range. If per-ignition happens somewhere at 60 – 80hz the knock sensor retards timing. If the blower puts out a frequency of say 78hz it would set off the knock sensor.

I am just thinking the current knock sensor can not decipher between blower vibration and pre-ignition vibration.

However, there very well may be something on the aftermarket that can. I think what I would want to know if I was buying a system is the specifics.

Can they tell you what range, frequency the knock sensor works at? Can they tell you what the blower range, frequency is? Or can they tell you how they can distinguish between two different mechanical pieces putting out about the same frequency (again I don’t know that to be true), because no matter how sophisticated the device or software for that matter it can not separate two identical frequency ranges, it can only distinguish “different” frequency ranges like 60hz and then 64hz.

Just something to think about as I have no idea about this product you are talking about. I only bring up my points for you or others to commit on so someone don’t “possibly” get stuck with a product that does not work correctly…

I don’t know that, but just looking out for L brothers…
 

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Discussion Starter · #11 ·
The company I started this post about is J&S Electronics. They've been doing knock sensors on vehicles for a long time, including a lot of racing and off-shore boats. They have systems on hundreds of roots supercharged vehicles. They are working on a system as we speak for the coil on plug Lightnings.

The question seems to be if he can use the factory sensor to run his system; Ford couldn't make it work but he feels he can. I know it will work with his new dedicated system, but if he can use the factory pieces the install should be easier and the kit should be less.

Jody
 

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I agree whole heartedly, I was just adding to the conversation to inquire more and see what can be drummed up idea wise. Let's see what happens, I eagerly await further information.

We're all in this together, that is what makes this such a great community. All the information the members put out help to let others who may not know as much make informed decisions. Let us know what transpires Jody. Thanks again!

Charlie
 

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Discussion Starter · #18 ·
I'D WIN said:
Jody,

Any key developing news on this system

-MM
None, but I haven't spoken with him for awhile. He was all excited and then quit responding to me. Maybe it was going to be tougher to do than he thought; he was determined to use the existing knock sensor.

Jody
 

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This is one of the best threads I have read in a long time . Hope someone can fix our problem
 
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