thirdgencompta

Ok, a knock sensor is a microphone that listens for detonation right? and the only thing it does is retard the timing if detonation is detected, right? so if my car does not detonate, do I really need a knock sensor?? Please correct me wherever I am wrong and let me know exactly what a knock sensor does and why I would need it. Cause the problem I am having is it seems that my engine makes a lot of noise, and when I drive it my timing seems to get "played with." I think the knock sensor is being tricked into thinking my car is detonating, so it sets the timing back and pisses me off.

kevinc

Pro:
Not all noise the sensor picks up is guaranteed to be actual detonation. Loose external hardware like a banging exhaust pipe can trigger it.

Con:
Not all detonation is detectable by the human ear over the ambient noise of the car...lack of spark knock sounds doesn't guarantee lack of detonation.

It's your car, pull it if you want. I wouldn't. Fix the problem causing your engine to make a lot of noise.

-Kevin

Fevre

Cars have run for years without them before FI. But to optimize your system you should run it. Your call.

ski_dwn_it

Well once again I will go against the grain and say that even if you have a knock sensor on your car, you can easily still encounter detonation.

With that said, the single best way to deter REAL detonation is though proper tuning and keeping and eye on things. Meaning reading your plugs.

Its VERY tough when you get long tube headers, RRs, loud exhaust, etc to keep the knock sensor from picking up false knock.

I know of about 20-30 racers that all have their knock sensors disconnected and have zero problems. But they all know what to do to prevent it too. So its not something to do blindly.

I have had mine disconnected (table zeroed ) for quite a while now on a 11.8:1 compression motor, with no problems. I have run 94 octane on the street at WOT with no audible pinging and no signs on the plugs. But for insurance I usually mix either toluene or race fuel to get about 97-98 octane for racing. The other 95% of the time I just run 93/94 octane and use self control.

For racing applications, I say they are a waste of time. That is my opinion, you can do whatever you like. So save me the critism that I'm sure some will come with.

Motors for 30+ years ran without them, with much lesser quality components and survived, so I think its pretty safe to say that so can I / those that choose to disconnect.

But I will say you need to make an informated/educated decision if you do make the choice to disconnect it.

Ed Maher

Exactly. If you know what you are doing, no problem not running a knock sensor. Just make sure to bypass it with the right resistor (3.9k for 730, 100k for 165)

Fun Fact: The knock sensor can only accomodate correction for minor knock anyway. If something is grossly wrong (bad gas, way off timing curve, etc) and you start to detonate hard the KS goes deaf and timiing is unchanged anyway. This is the only time you'd really NEED a KS, and it can't even help. This is also exactly why i stopped running a knock sensor. Once i realized it was only there to throw a wrench into my tuning on minor knock and false noise i decided it was gone.

But if you don't know what detonation looks like on plugs, and don't get consistent quality gas, and only tune by seat of the pants then i'd leave the KS in to be safe.

SLP_GTA

iTrader: (1)

Ed you have to either change the value in your prom to 0 or use a resistor? which KS do I have? 91 L98

ski_dwn_it

The easiest way to get around the knock, and not have to worry about codes, is just zero out the tables. That is easy to change back also. I have even considered burning two proms. One for the highway, with it in, and one without for the track.

But I like to live on the edge. So I just leave it alone with all zeros in the tables.

5SIZ

hmm, I have false knock on my sensor and it's driving me mad, I know motors have ran for years upon years w/o a KS, so why should mine .

If I have an 87 MAF car, how would I run the resistor? do I connect each side to a wire or something.

any help will do, thanks.