Fallstar01

Well, here is the situation. I have a feeling that I've got very subtle knocking going on and I can't tell for sure. I'd like to fit a knock sensor to the engine strictly for detection (don't want it messing with my timing, i'll do that myself). Does anyone have any suggestions for placement? Also, would there be a way to hook it up to an led or voltage meter?

fordguy17

i think knock sensors go into what would be the lifter valley on a pushrod motor, and they just pull timing when they detect knock. i don't know if you can get them to not pull timing and hook up an led....

Fallstar01

Thanks, for the info.
I'm looking at some products from this company:
http://www.jandssafeguard.com/safeguard.html

4600cc

Well, hold on there buddy. You can't just come in here and tell us your 02 GT don't have knock detection. You're modified obviously and we need to know just what the hell you have in there? What ignition and injection computers do you use?

JD1969

Your car should already have a knock sensor, and you should be able to hook it up to a tuning program like SCT (and I don't mean some crappy hand held) and see exactly what rpm it is knocking at.

Fallstar01

For some reason, I was led to believe that my car didn't have a knock sensor from the factory (unlike GMs). And I heard it from a ford tech no less. Maybe this guy is incompetant and just plain wrong but I gave the engine a quick look and didn't notice one anywhere.

I've got access to the SCT software package so it would be good to know if my car is equipped with a sensor, and if it's working.
I'm using the stock ECU with an SCT tune with TR-6 plugs gapped at .035, 42lbs injectors, lightning MAF, and Aviator fuel pump on a supercharged mustang, the rest of the fuel system and ignition is stock.
I'm concerned that I may have mild but detonation in lower RPMs, especially when accellerating. On a dyno, you usually don't pay much attention to RPMs below 3000. I'm planning to hook up a wideband and datalogger at some point but I'd like to know for sure that all knock has been eliminated.

It's not obvious if the timing is being retarded when I hear the sound but if it is, it's not enough.

It's especially an issue on really hot days. I'm using sunoco 94 gas so without expensive, additives, I can't go any higher without making a long trip for expensive race gas.

4600cc

What you need to do is have your ignition map and AF ratio map tuned. Give this guy a call Ben Salasko [bensalasko@yahoo.com]

Chopper

Two valve engines do not have knock sensors.Four valve engines do.Yes I think you could hook one up but I have no idea how they work.Are they an on off switch or do they modify a signal coming from the ECU?You could buy one and experiment to see how to get it to do it's thing.You could hook up a digital ohm meter and hit the knock sensor with something and see how the ohm meter reading reacts.Maybe you could hook one up to an ociloscope.Something that could be added on as a stand alone knock detector could be an item that would sell rather well.Best of Luck.

4600cc

Well, look at this expert.




All 2v, 4v, and 3v, 4.6L, 5.4L, 6.8L mod motors have knock sensors starting from when ECC-V was introduced. ECC-V was designed with emissions in mind, knock sensor is a major contributor to that.


A knock sensor is a microphone, you need complex hardware or software to identify knock. Knock sensing device actually filters the knock sounds out from other sounds and pulls timing as knock is detected. It is very complex and requires fast hardware and complex software.


Hook it up to your stereo's mic input.


Resistance will stay the same even if you it with a hummer. The ohm meter does not have to be digital, it could be a cheap analog variety.


If the osciloscope is sensitive enough, you will see amplitude modulation as you make noise.


Nah. They're too damn expensive. You better off developing good ears and listening for the knock.

4600cc

When talking knock sensing, think speach recognition. Very complex, and different humans speak differently. A knock device is something that manufacturer makes for an engine, it will not work well on a different engine.

I wanted to post about knock sensing in here when I read the original post, but though the author had modified ignition and needed a way to detect knock with that ignition. Too many people are confused about EFI and electronic ignition!!! From the damn speeda timing adjuster to knock sensing and COP, people are too damn confused!!!