martyo
MO derator
I was not saying anything counter to that.
Knock Sensors....On or Off??
- Thread starter Marauderjack
- Start date
I was not saying anything counter to that.
I think that is the expected behavior, called hysteresis of knock. Once detonation begins, timing must be reduced significantly below the "correct" non-detonating timing setting to stop the pinging.
Let's say your engine runs good at 28 degrees advance, and pings at 30 degrees. One would think that pulling the timing back to 28 degrees would cause the detonation to stop, but it doesn't. It might require reducing timing to 24 or 22 degrees to quench the detonation. After the detonation is stopped timing can then be safely set back to the baseline.
This is well-understood, and incorporated in some PCM knock logic. What did they do in the Marauder PCM? I don't know. There are numerous other details, such as only listening right after ignition to help ignore extraneous noise, etc.
martyo
MO derator
As I said, if I recall correctly the factory programming calls for a reduction of 10* of timing. The idea being to clamp down on the detonation as quickly as possible.
The problem is that this effectively neuters the engines ability to make power
Of course, the PCM in the Marauder is technology that is well older than ten years and processor speeds and functionality have taken some good strides forward since then. Nonetheless, most of us are stuck with the processor platforms that came with the car and changing them out is not a simple, or cheap, task.
martyo
MO derator
Zack when you guys did that, did you retune your cars?
chief455
New member
I like the idea of this, and hopefully they sensors they sell are better than 2004 stuff
this is a concern:
10) Once you have the engine running on the J&S unit, you are ready to test the knock sensor. The unit will not detect knock unless the following conditions are met:
a) RPM must be above 1750 RPM
b) Vacuum drops below five inches.
I know detonation happens at cruise RPM, and vacuum could be stronger than 5hg - still going to look into this system. $650 plus $50 per extra sensor could save an engine.
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Zack
Turbo Marauder
Yes, Jerry W retuned them for us.
Knock sensors are great for adding timing, not removing it
I like the idea of this, and hopefully they sensors they sell are better than 2004 stuff
this is a concern:
10) Once you have the engine running on the J&S unit, you are ready to test the knock sensor. The unit will not detect knock unless the following conditions are met:
a) RPM must be above 1750 RPM
b) Vacuum drops below five inches.
I know detonation happens at cruise RPM, and vacuum could be stronger than 5hg - still going to look into this system. $650 plus $50 per extra sensor could save an engine.
I manufacture the Vampire system. You are quoting from the instructions for a forced induction application.
For naturally aspirated applications, I change the enable point to 15 inches vacuum.
The sensor is just a microphone. It's what you do with the signal that matters.
Right. It's all in the signal processing.
chief455
New member
Glad you found this to provide factual information!
So, why not enable a forced induction system microphone at 15 inches, just in case the detonation (bad gas, mechanical part failing) is happening before boost?
Would this cause 'false knock' system reactions?
Jeronimojc
Boost Hunter
Awesome system!! I wish there was a more affordable kit though.
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