What's the purpose of having a knock sensor?

Is it better to just have a p28 and have it disabled?

 

Knock sensors alert you when the car is running too lean and is detonating. Probably one of the most useful sensors that your car can have, really saves the engine because often times you can't hear the "knocking" when the car detonates.

So... keep it.

 

Purpose of it? to throw codes and **** you off

It detects knock/detonation in the engine. If/when it knocks, it sends a signal to the ECU then CEL comes up...I think someone add/correct me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SkoundrelUSA &raquo;</TD></TR><TR><TD CLASS="quote">
It detects knock/detonation in the engine. If/when it knocks, it sends a signal to the ECU then CEL comes up...I think someone add/correct me.</TD></TR></TABLE>

I thought that it retarded the timing to reduce detonation; mostly when under heavy loading or when using the wrong fuel.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoXer &raquo;</TD></TR><TR><TD CLASS="quote">

I thought that it retarded the timing to reduce detonation; mostly when under heavy loading or when using the wrong fuel.

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Right, forgot about that

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<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoXer &raquo;</TD></TR><TR><TD CLASS="quote">I thought that it retarded the timing to reduce detonation; mostly when under heavy loading or when using the wrong fuel.</TD></TR></TABLE>
Interesting, I didn't know that the knock sensor actually fixed the problem too? I always thought it was to tell you "hey, you're engine is getting fuxored up"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SovXietday &raquo;</TD></TR><TR><TD CLASS="quote">
Interesting, I didn't know that the knock sensor actually fixed the problem too? I always thought it was to tell you "hey, you're engine is getting fuxored up" </TD></TR></TABLE>

Nah, that's what the rest of them do

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SkoundrelUSA &raquo;</TD></TR><TR><TD CLASS="quote">

Right, forgot about that

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It's alright; old age and all

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoXer &raquo;</TD></TR><TR><TD CLASS="quote">

I thought that it retarded the timing to reduce detonation; mostly when under heavy loading or when using the wrong fuel.

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Yes, but I think its important to include the following to help people better understand things...

The knock sensor can only pull so much timing. I think its a max of 15-20 degrees. The knock sensor also just "listens" for a specific frequency. It honestly has no way of telling for sure that what it hears is knock, but 9 times out of 10, its correct. Keep in mind though there is room for error. "Race" motors tend to be a little noisier then a stock engine. Piston noise, valvetrain noise, it adds up. This can cause the knock sensor to pull timing when there is no need to and thus effect hp output levels. I think what happened is people saw the race teams disabling the knock sensors and then jumped on the bandwagon assuming that "because race teams do it it must be good".. There are some reasons to disable it as I outlined above, but for 90% of the people who are rolling around with nothing more then I/H/E, I would leave things as they are.

EDIT: Also, I am not 99% sure, but I believe you will only get a code when knock is 'beyond the control' of the knock sensor or the ECU detects a problem with the sensor itself.

 

Correctm you will not get a code if it's just doing it's job. Only if it is faulty or can't fix the problem.

Definately a good sensor to keep.

 

Yes, if the timing is totaly retarded, and there is still knock, you will get a CEL.