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Go Back JeepForum.com > Models > Jeep Cherokee & Comanche Forums > MJ Comanche Technical Forum > Knock Sensor?

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Unread 10-04-2012, 07:59 PM   #1
JeepComanche89
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Knock Sensor?

Hey, I found out the knock sensor broke off my 89 comanche motor when we were puttin it in. I looked one up and there 60 plus dollars . Do you think its worth getting one from a junkyard, do they have a tendency of going bad? Or schould I just buy a new one. Let me know what you think, thanks in advance.

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Unread 10-05-2012, 09:01 AM   #2
DeejayZeejay
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I was told knock sensors are worthless.... They tend to not be accurate. Not sure if they go bad. But if you get it cheap at the junkyard, its worth a try.
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Unread 10-05-2012, 02:00 PM   #3
JeepComanche89
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Hmm, does that mean it will run without one?
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Unread 10-05-2012, 11:04 PM   #4
DeejayZeejay
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Dunno. Maybe...
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Unread 10-05-2012, 11:52 PM   #5
mj40
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knock sensors for adjusting timing for the computer, it'll run without, but any knock/pinging in the engine and the computer will not see it or adjust the timing for it..and you may get a check engine light when the computer see's its gone.
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Unread 10-06-2012, 11:10 PM   #6
ftpiercecracker
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You need a Knock sensor, period. Yes it will run without it, but i would not advise it. You can try a junk yard, just make sure to replace it with a good one when you do get the money.
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Unread 10-07-2012, 06:15 PM   #7
JeepComanche89
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Okay, thanks for the help. Guesse ill just have to buy a new one to be safe, dont want to risk anything if it does matter
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Unread 10-07-2012, 10:46 PM   #8
cruiser54
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Quote:
Originally Posted by mj40 View Post
knock sensors for adjusting timing for the computer, it'll run without, but any knock/pinging in the engine and the computer will not see it or adjust the timing for it..and you may get a check engine light when the computer see's its gone.
No check engine lights on a REnix.....
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Unread 10-07-2012, 10:47 PM   #9
cruiser54
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Originally Posted by JeepComanche89 View Post
Okay, thanks for the help. Guesse ill just have to buy a new one to be safe, dont want to risk anything if it does matter
A good used one would probably be fine. They rarely fail.
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Unread 10-08-2012, 01:23 PM   #10
97_4popper
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Hell, I didn't know they had 'em.
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Unread 10-08-2012, 06:26 PM   #11
JeepComanche89
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Quote:
Originally Posted by cruiser54

A good used one would probably be fine. They rarely fail.
If i can find one ill probably just do that, but if not ill buy new
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Unread 10-08-2012, 06:27 PM   #12
JeepComanche89
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Originally Posted by 97_4popper
Hell, I didn't know they had 'em.
Me neither, had to post on here to find out what it was haha
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Unread 10-08-2012, 09:48 PM   #13
ftpiercecracker
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FWIW renix motors also have 3 separate temperature sensors. 1. back driver side of the head 2. driver side of the rad 3. driver side of engine block, under the intake man.
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Unread 10-08-2012, 10:12 PM   #14
cruiser54
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Coolant temp SENDER at the rear driver's side of the head, for the instrument panel gauge or light. Coolant Temp SENSOR to give info to the ECU is located on the driver's side of the block.
Coolant Fan SWITCH is located in the radiator on the driver's side lower to engage the electric fan.
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Unread 10-09-2012, 05:44 AM   #15
JeepComanche89
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I know i have the one under the manifold, im not sure about the one in the head, and i replaced the rad and im pretty sure it doesn't have any place for a sensor. And i defiantly do not have an electric fan.
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