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knock sensors

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Old Jul 29, 2004 | 06:07 PM
  #1  
damimfast's Avatar
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From: new york
knock sensors

anyone knows what a knock Sensors is?
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Old Jul 29, 2004 | 08:06 PM
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From: Bartlesville, OK.
It's a microphone that 'hears' best in the frequency ranges of the sounds produced when an engine's combustion process produces pings or knocks. The more sound energy in these ranges, the stronger the signal generated by the sensor. An engine ecu is programmed to respond by reducing ignition advance, etc. when the signal for a knock sensor rises to or above a threshold value.

One more point; finding that magic threshold point on a rotary engine can be very quick, painful, and expensive ...
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Old Jul 31, 2004 | 12:55 PM
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From: new york
can i run my car with a bad knock Sensors?
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Old Jul 31, 2004 | 01:19 PM
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From: Buckhead, Atlanta
well if he just said that the ECU actively alters engine functioning based on the signal from the knock sensors, it doesn't take matlock to figure out that it would obviously impact the way the car performs if these sensors are bad...or malfunctioning

no?
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Old Jul 31, 2004 | 01:25 PM
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From: albany, ny
a bad knock sensor will make your car run like crap. the ecu will retard timing and limit boost if you are stock. the factory knock sensors are filled with a black silicone type goo that eventually deteriorates and runs out of the sensor making it give much higher knock readings.
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Old Jul 31, 2004 | 01:33 PM
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From: NoVA
this is interesting. What are the symtoms of a bad knock sensor? this might be very important to me. please be specific
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Old Jul 31, 2004 | 02:24 PM
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From: albany, ny
on my car when the knock sensor went bad, the car would hesitate when i got on it hard. also, i noticed that the car would do this even more when the temps were hot. i remember going to work on a cooler morning when i was having the problem and the car ran so much better. i think it was a function of the colder temps keeping the goo inside the sensor harder. are you running a stock computer??
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Old Jul 31, 2004 | 02:32 PM
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yep, stock computer. I am getting a high idle and its running extremely rich. I am also seeing a tad bit higher on the oil pressure at certain (almost random) points. I am getting 4 psi (might just be a leak) and sometime a jerky throttle from idle.
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Old Jul 31, 2004 | 02:49 PM
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From: albany, ny
your issue sounds more like a vacuum leak. you can adjust the idle with the adjustment screw just in front of the uim on the right. i would also take carb cleaner and spray it around the upper and lower manifolds while the car is running. if you notice the idle dropping or the car stalls while you spray a certain area, that is where your leak is. a knock sensor is more likely to cause problems under load and not at idle. hope this helps.
andy
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Old Aug 6, 2004 | 01:18 AM
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oh man this answers alot for me, doh! I recently pulled the code out for "knock sensor" from the check engine light, thats why my boost has been having hesitations... time to call Ray ASAP!
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