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Discussion Starter #1 (Edited)
So, here's my first post in this shindig. This has worked very very well for me so I thought I'd share the wealth. I was having HUGE problems with my knock sensor going insane during datalogs... I brought my final timing down to only 5 degrees at 2500-3000rpm and .5 load, and it still showed 8 degrees of knock retard... So basically, it wasnt knock lol

You may have heard about those expensive knock monitoring thingys "The Knock Box" or "phormula" among others... with the fancy noise canceling headphones, etc... well quite frankly... I dont have $150-300 to blow on this...

There are the other options that give you a light show when they think they hear knock, for around $50-100. But on a noisy engine like mine, who's to say they would be any different from the stock sensor in a datalog? They seemed like a possible waste of money to me.

After replacing my sensor and realizing it is just a microphone, I decided to search around to see what people have done to listen to it. And as it turns out, its really easy to do. Fancy boxes need not apply.

All you need is a 0.1uF (uF = microfarad) capacitor, a 1/8" stereo plug or jack (male or female, you have to find out what you need for your HU), some wire, a ring or spade terminal, and a headunit with aux-in.

1. Solder a length of the "some wire" to the tip and ring wires of the stereo plug. Solder the other side to one lead of the cap.
2. Crimp/Solder a second length of the "some wire" to the terminal. Solder the other side of this to the sleeve (ground shield) wire on your 1/8 plug.
3. Go in your car and remove the trim panel covering the ECU and fuel cutoff switch. There are two plastic flathead screws and a clip you cant see.
4. Ground the terminal on the ground bolt next to the fuel cutoff.
5. Take off the black plastic cover from your ECU wiring and shove the open lead of the cap into pin #57 (if you have a zetec, not sure about duratecs pin #). There are other methods to get the signal (t-tap, splice, cut and solder, etc) but the shoving in the hole method worked fine for me and is 100% reversible.
6. Plug the plug into your aux-in (duh.)

Now turn your stereo on the aux channel and listen. :) If it is too quiet at full volume, you havent shoved it in pin 57 far enough. I do have to keep it at max volume during tuning to hear over my exhaust. I also have a lot of whining noise like alternator whine, but you can easily hear everything over it. I plan on building a bandpass filter later to fix this.

If you are wondering what knock sounds like using this method, this is a very good clip. In the beginning-ish you hear the very rough sounds of heavy knock that you can hear outside the car, "rocks in a tin can". Then in the middle of the clip it transitions to the "pinging" that is indicative of light, inaudible knock (that can still blow your motor!). I have heard this exact same pinging noise while tuning, so I can confirm this is in fact knock. It has made that noise for me both on high timing and slightly lean pulls.

knock sensor sound with knock CLICK ME

here is the explanation of a "tip-ring-sleeve" connector if you are confused about what i said up there http://en.wikipedia.org/wiki/TRS_connector

This website was particularly helpful:
http://home.netcom.com/~bsundahl/knock/listen/listen.htm
http://home.netcom.com/~bsundahl/knock/sound/KnockSounds.htm


Cheers! :banana:
 

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Pete awesome post man great info. I know my car when I logged it a while ago it showed the sensor picking up something and I'm pretty sure my car doesn't knock but I do have cams that are loud and Im sure is making a noise that can be picked up by the seonsor.

I might have to try this sometime :thumbup:
 

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The factory Zetec knock sensors are basically useless, that's why most people running FI disable them. Otherwise, they pull timing all over the place as you noted and if you tune around them it ends up resulting in a crappy, powerless tune. This is an awesome idea though and I'm going to try this out before I dump $700 on a J&S system. It makes inaudible detonation audible, which is what makes this so awesome. And, I happen to work in the soldering industry...so it works very well.

It's worth noting, however, that capacitors are polarized (they have a positive and a negative) so the one going to pin 57 needs to be the positive wire and the one going to ground needs to go to the negative lead on the capacitor. Other than that, it looks like you've got a great system here. THANK YOU! :)
 

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Discussion Starter #5 (Edited)
I think you have the wiring confused, the capacitor is only there to prevent any DC bias from your headunit from reaching the ECU and screwing it up. The cap is not connected to ground. it is in series between the aux-in (tip and ring) and pin 57.

The only ground is the shield wire (sleeve).
 

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Good point, I just skimmed through the install directions and didn't see anything regarding polarity so I figured I'd put in my $.02.

On a side note, I'll be doing this in the next couple weeks and I should be able to run the mic/input jack to my laptop, and the headphone jack on my laptop to the input on my speakers in my car. That way, I can listen to the detonation over the radio in my car. I'll take some pics of the install along the way so people can get a better idea.
 

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Discussion Starter #7
Yeah that's how this is I have it going over my car stereo. You can just go straight to the auxin on the radio and skip the laptop.

But the laptop would be nice for recording and playback. I was thinking of doing that but never got around to it.
 

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Nice writeup. I found this just now.

http://home.netcom.com/~bsundahl/knock/listen/listen.htm

I think something more along the lines of using a set of headphones like the above shows would be cool.

Also I have heard that the 05+ duratec knock sensors are a little less sensitive to random engine noise. I'm wondering if the connector is the same as the zetec.
 

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Knock sensor sensitivity is set by the ecm and not the sensor itself.

Nice writeup. I found this just now.

http://home.netcom.com/~bsundahl/knock/listen/listen.htm

I think something more along the lines of using a set of headphones like the above shows would be cool.

Also I have heard that the 05+ duratec knock sensors are a little less sensitive to random engine noise. I'm wondering if the connector is the same as the zetec.
 

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Knock sensor sensitivity is set by the ecm and not the sensor itself.

The microphone is supposedly a different design. Has nothing to do with the ecu.

Sensitivity meaning it is not capable of hearing some of the light normal engine noise that the zetec sensor hears.
 

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Discussion Starter #11
it is certainly possible that it has different bandpass filtering. Regardless, this has been working great for me :)
 

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Just a quick update on my end, since I already have an aftermarket head unit with a dual RCA to headphone jack line coming out, I bought a female-to-male cord (6ft) and a .1microfarad capacitor (250vdc, overkill but it's a decent one) from RadioShack for about $7.

If you buy all of the nicer gold-plated connectors and the RCA to headphone jack you're looking at about $20-$25 for something that allows you to be your own J&S--and you know your sensitivity is more accurate because you can actually hear the detonation.

In the next week or so I'll be installing mine and I'll take pics as I do so. It won't mimic everyone's setup, but it'll give you a good idea of what to do with an aftermarket head unit similar to mine.
 

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nice. I'm soldering mine right now, since I just finished my closed loop MTF tonight, and its open loop MTF then spark tomorrow ;) i just hope doing laundry doesnt get in the way. F laundry day. lol
 

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Discussion Starter #14
you guys are going to **** yourselves when you are tuning and you get to the spark where det starts.
 

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Ha, I'm not doing the tuning myself, Randy is--I'm just inserting myself as a human J&S because I'm going for big HP and don't feel like grenading my engine. Not as adventurous as you guys ;)
 

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Discussion Starter #17
Thankfully I was alone when i heard i the first time so nobody knows I soiled myself too.

...oh wait now you guys know :bang:
 

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Please let me know if this is an accurate representation of what you did to make this setup work properly. I'm a little lost with your explanation, but it's a simple concept so if I'm off I'm sure it's not by much.

 

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yep thats what pete was getting at.

btw mine is hooked up now, too... and works great! fortunately I haven't observed any knock events yet, but I'm sure I will once I start tuning my Borderline knock table
 

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ill have to make one of these really soon too.. when i get the PRP this could be a great tool..

Pete, do you have to turn the radio up pretty high to hear it or will it be very audible at lower levels?
 
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