not sure how bad this is, knock sensor

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Oct 23, 2018 | 10:29 AM
  #1  
so I noticed my car acting a little funny, my knock sensor is unplugged because its a 305 knock sensor and I have a 350, but somehow the wire slipped down and was sitting on the exhaust and was burnt, I hope this wouldn't fry my esc module and that would cause it. I will replace the burnt wire as soon as I get some time.

it is just running a little rough at idle and as I creep in gear it more or less is jerky and not a smooth roll. any ideas? oh and my wide band 02 shows its running in and out of lean.
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Oct 23, 2018 | 10:54 AM
  #2  
Re: not sure how bad this is, knock sensor
The knock sensor is a passive piezoelectric "microphone" that transmits a very low voltage signal that is then interpreted by the knock control..... if it is unplugged nothing will happen. The some ECM's can throw a fault code and could reduce timing but for the most part the ECM is just "blind" to knock events and will otherwise run normally.

Rough idle is probably unrelated. At any rate the fuel mixture control does not depend on the knock sensor so if you are lean it is not related to that. Incidentally a misfire will drive the O2 sensor lean. Sounds like you have a misfire.

GD
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Oct 23, 2018 | 11:00 AM
  #3  
Re: not sure how bad this is, knock sensor
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Oct 23, 2018 | 11:01 AM
  #4  
Re: not sure how bad this is, knock sensor
ok thank you for your reply, I will start by changing my spark plugs. and will keep you all informed. thank you again.
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Oct 23, 2018 | 11:03 AM
  #5  
Re: not sure how bad this is, knock sensor
hi tuned performance, it has been a little bit my friend...

quick question as well, could I just cut off the bad wire and re-splice a new wire on the knock sensor or will this cause an issue?
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Oct 23, 2018 | 11:11 AM
  #6  
Re: not sure how bad this is, knock sensor
Hello happyhapka, A splice will work fine. If there is enough slack on the wire so you can solder it and shrink tube it. Other wise they do make a shrink tube style butt connector that has glue in it. This will help to prevent corrosion in the future.
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Oct 23, 2018 | 11:14 AM
  #7  
Re: not sure how bad this is, knock sensor
ok thanks. ill be getting a new cap and rotor and spark plugs and hopefully will replace it tonight.
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Oct 23, 2018 | 09:01 PM
  #8  
Re: not sure how bad this is, knock sensor
Ok, i got new plugs and a o2 sensor... i didnt do my plugs yet but i did my o2 sensor, it was waaaaayyyyyy loose, so im sure it was sucking air threw there which could be part of the problem. The problem still exists but i think the computer needs to re learn, im going to reset it. Tomarrow im going to do the plugs. Any comments on the loose o2?
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Oct 23, 2018 | 09:11 PM
  #9  
Re: not sure how bad this is, knock sensor
Any exhaust leaks before or at the O2 sensor will drive the sensor lean due to excessive unburned oxygen present in the exhaust. Also the single wire sensors ground through the exhaust so if you have a poor connection you will get a lower or possibly non-existent voltage signal from the sensor - which will be interpreted as a lean condition by the ECM. Either way it will add fuel like crazy to try to compensate. What is your BLM?
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Oct 23, 2018 | 09:16 PM
  #10  
Re: not sure how bad this is, knock sensor
I did the 3 wire o2 mod, but still, i will still do my plugs tomarrow.. thank you for the reply.
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Oct 23, 2018 | 09:47 PM
  #11  
Re: not sure how bad this is, knock sensor
I will data log the car in the morning on the way to work and take a picture of it for you.
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Oct 24, 2018 | 08:14 AM
  #12  
Re: not sure how bad this is, knock sensor
Three wire sensors still ground the sensor through the exhaust. They just have a separate power and ground for the heating element. The heating element has its own ground so the ECM (not ours - newer ones) can monitor the circuit.

GD
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Oct 24, 2018 | 09:26 AM
  #13  
Re: not sure how bad this is, knock sensor
I logged the car this morning, this is average. I am like 10-15 miles away from work.
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Oct 24, 2018 | 09:27 AM
  #14  
Re: not sure how bad this is, knock sensor

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Oct 24, 2018 | 09:28 AM
  #15  
Re: not sure how bad this is, knock sensor
Ill get another one at lunch
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Oct 24, 2018 | 03:05 PM
  #16  
Re: not sure how bad this is, knock sensor

I logged it at lunch.. . It is average again.
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Oct 25, 2018 | 09:44 AM
  #17  
Re: not sure how bad this is, knock sensor
Well looks like i had a few burn threw on my wires but the main problem was my #6 spark plug, it was crippled, changed my wires and plugs and she was like new.

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