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Knock Sensor


Guest Pprince147
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Guest Pprince147

Can't find much here or in the book I have on this. I checked codes and 14 and 34 came up.

 

Does anyone know 1) what this is 2) where it is 3) what it does 4) if it could be causing some of my probs in my other post?

 

93 se auto

 

Duh, went back and searched differently and saw you already posted on this. But due to the cost and apparent difficulty I really don't want to mess with this if it's not the problem I'm having right now. Did manage to test drive it this morning. Able to get some rpm's out of it and go about 30 mph but it still fights me with not wanting to accelerate, I really have to baby the pedal.

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I'm not fully sure how it does what it does, but its located under the intake in the V of the block. PITA to get to, but there's a write up on here on how to change it out. I didn't have the time or garage to swap mine when it went out, and it ended up costing like $550 in parts and labor (actually, I had a leak fixed while they were in there as well).. :o The stupid sensor alone is over $150 easily.

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Guest Pprince147

gawd i hate to hear that.

 

So what was the problem that you had to have yours replaced?

 

I've taken it to two "good" mechanics here, tired of dealing with em but my options are limited. After sitting on it for a week, first one said "I don't have the right equipment to test it". Second one tried to sell me replacing the timing belt at like $600. I don't know what's wrong with it, but I DO know it's not the timing belt.

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The knock sensor is an acoustic device(just for fun lets call it a microfone) that listens for detonation(knock).

If it detects detonation(commonly caused by bad fuel) it retards the timing to protect the motor internal parts(mainly pistons).

 

That's a simple way of looking at the knock sensor but since I don't even have a Pathy yet I have no clue as to where it is. Most cars have them in the back of the head in a place that is hard to get to.

 

If you would like to see a picture of a piston that has been affected by detonation just let me know. I have a bunch. :D

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The knock sensor is an acoustic device(just for fun lets call it a microfone) that listens for detonation(knock).

If it detects detonation(commonly caused by bad fuel) it retards the timing to protect the motor internal parts(mainly pistons).

 

That's a simple way of looking at the knock sensor but since I don't even have a Pathy yet I have no clue as to where it is. Most cars have them in the back of the head in a place that is hard to get to.

 

If you would like to see a picture of a piston that has been affected by detonation just let me know. I have a bunch. :D

Thats right on, detonation can also be caused by running lean, too much air not enough fuel although you won't see this problem much on a stock n/a engine unless something major is wrong. With a turbo, running more boost then the stock fuel system can handle or improper tuning it is common. Later.

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Just to clarify....

when I sayd "bad gas", that doesn't necessarily mean gas that is spoiled or inferiorin in some way. However, it could. :confused:

By saying "bad gas" just means gas which has an octane rating insufficient for the engine.

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My understanding is that when it the sensor is "bad" it is stuck with the "knock" reading and proceeds to mess with the timing and/or fuel in an attempt to keep the engine from knocking, even though it isn't. Not sure if this is really the case, maybe somebody could elaborate. I know that when mine was toast and threw the code, it wouldn't really idle but would drive relatively normal, and it got horrible mileage.

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  • 2 months later...
Guest ksakella

Just changed my KS, too. Actually still in the middle of it! Can a bad knock sensor cause piston skirts to break off, or piston tops to chip(detonation)? Just curious, because my first motor (260K miles) bit the dust a couple of months ago, and the new motor started to make some messed up sounds before I checked the ECU and found the blinking 34.

Compression is still good, luckily!

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