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I'm trying to use my XCal 3's data logging capabilities to figure out if my engine is suffering from spark knock. I hear a very noticable ping/clang coming from the front of my car under certain conditions. Basically it happens while doing between 60-80 kph, around 2k RPM, and only when the engine is under load.

Does anyone know what parameters I should log to look for valves tapping/spark knock? And what exactly am I looking for on the graph to see if it is happening?
 

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Monitor spark and rpm. You should see a drop in spark as the rpm rises if the knock sensors are working. Normally spark will rise as rpm increases.

Some PCMs also let you monitor the knock sensor it self.
 

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QUOTE (SHOZ123 @ May 15 2009, 12:40 AM) index.php?act=findpost&pid=725278
Monitor spark and rpm. You should see a drop in spark as the rpm rises if the knock sensors are working. Normally spark will rise as rpm increases.

Some PCMs also let you monitor the knock sensor it self.[/b]
How do you know if your knock is working? I found mine, but it is as old as the car.
 

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If the knock sensor is working it will retard the spark.
 

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If your knock sensor is not working, what are some symptoms to look for?
 

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If it is not working it will set a code. The factory programming is not very aggressive at controlling knock. Excessive spark knock is more a problem arising from engine carbon build up or ingestion of large amounts of blowby. There is the possibility that the gas you are using is crap. Might try a different brand.
 

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How would you describe spark knock? For istance if you rev the motor from idle, and you get a knock before the rpms come up? Or like a light tapping under high load, like say when the car shifts from first to second?
 

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Spark knock is more like a rattle than a tap or knock. At least that's how I remember the sound.
 

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Thanks for the info guys.
 
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