turbodisplay
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| posted on 2/1/10 at 03:10 PM |
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Knock sensor question + where to get cheap
Just changed the knock sensor on the celica as it was giving me lots of problems.
They are VERY fragile so I decided to replace with a different type.
Fitted a bosch I had lying arround from a scrap yard - didn`t work.
Researched and found out that the sensors are resonat at 7khz.
Simple made a filter circuit to only pass at 6-8Khz.
It works but only with the gain very high (amplifing between 10 - 50 times).
So questions are:
1) As this sensor is about 10 years old could the output be low due to the age?
2) Anyone know of a cheap type to get a brand new one, ie off a 95 astra.
Looking for one with an 8mm hole, bosch minitimer connector.
Thanks
Darren
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flak monkey
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| posted on 2/1/10 at 03:15 PM |
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Should either work, or not work.
If you look on the megasquirt site theres a circuit for a knock detection amp/filter
Found this on ebay
Clicky
Sera
http://www.motosera.com
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turbodisplay
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| posted on 2/1/10 at 03:29 PM |
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Thats not a bad price, looked a ebay yeaterday but must have missed that.
Problem is that the sensor can`t be on a lead.
Thinking about it, the gain is so high that I could be picking up electrical interference. The ecu throws a fault code if it does not see any noise,
if it sees too much it will make the car horrible to drive so it is a fun ballancing act!
Darren
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scootz
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| posted on 2/1/10 at 03:58 PM |
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Sorry for the slight hijack Darren... does anyone know of any ECU's that can monitor 4 knock-sensors?
It's Evolution Baby!
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turbodisplay
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| posted on 2/1/10 at 04:08 PM |
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I would say no. But clever electronics could be used.
Two twin knock sensor interfaces, 1 processor, and a knock generator to feed a "false" knock signal would work.
Darren
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martyn_16v
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| posted on 2/1/10 at 05:25 PM |
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quote:
Originally posted by turbodisplay
Looking for one with an 8mm hole, bosch minitimer connector.
Most VW/Audi from the 90's (and probably newer).
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Werner Van Loock
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| posted on 2/1/10 at 06:11 PM |
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slightly more expensive:
http://shop.vems.hu/catalog/product_info.php?cPath=1_12&products_id=114
http://www.clubstylus.be
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turbodisplay
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| posted on 3/1/10 at 10:39 AM |
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Thanks
for the replies, I will try the motor factors on tuesday.
Either tat or see if a few secondhand ones work better.
Thanks
Darren
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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MikeRJ
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| posted on 3/1/10 at 05:24 PM |
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quote:
Originally posted by turbodisplay
Researched and found out that the sensors are resonat at 7khz.
Simple made a filter circuit to only pass at 6-8Khz.
It works but only with the gain very high (amplifing between 10 - 50 times).
The peak response of the sensor depends on the application, and is related to the bore size of the engine. If you want to use a different part then
try to find something from as similar sized engine to yours as possible.
The reason you need lots of gain is because you are trying to extract signals outside the bandwidth of the device.
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