ive been thinking about doing this. I want to wire a LED so that when ever the engine sees a knock it lights up, anyone have a good idea how to do this? Im pretty good at wiring/taping wires/sodering, you name it electrical. Im just dont know much about the electrical in a car.
2006 Black Cobalt SS Supercharged G85
13.91@102.77
The engine always see's knock, you'd have to pick a limit. The knock sensor puts out a voltage depending on how much knock it see's. You'd have to determine a voltage limit and find a suitable resistor that flows enough voltage at that resistance to light up the LED.
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what about the Casper's Turbo-6 Knock Sensor? That is always an option if the LED falls through.
well im kinda looking to do this the el cheapo way. Well if i put a resister and LED in line with the knock sensor, wont that mess up the knock sensors readings?
2006 Black Cobalt SS Supercharged G85
13.91@102.77
you would have to hook it up in parallel so it wouldnt effect anything. As far as hooking an LED up to that sensor, Yes you can. All that sensor is, is a Piezo crystal that when under pressure or a "knock" generates its own voltage. Hense only one wire coming from it. The PCM determines at which voltage it reads from the piezo that its become hazordous to the engine. As said before it for the most part due to the violance of a combustion engine will pretty much always create a voltage but again the PCM determines at which voltage it becomes concerned.
This then brings me to the question of why would you really want to hook up an LED in the first place when your dash has one built right in. When your PCM sees a knock that is beyond its engine safety parameters it flashes your check engine light. so really why go to all the trouble of messing with it. Just my thought.
ASE Master Certified Automotive Technician
If he's not using the factory computer anymore (such as myself) he wouldn't have that luxury of relying on the flashing check engine light to tell him when he's seeing too much knock.
I think this LED is more trouble then its worth, but I hope you get it working and give us a write up of how you did it.
very true that if he were no longer using the stock ECU and went stand alone his MIL would no longer flash but thats a given
ASE Master Certified Automotive Technician
well i know that the check engine light will flash when there is detonation, but it has to be pretty severe for it to happen. Im looking to see when im getting knock retard thats killing power. Not severe detonation.
I guess the only real obstacle i would need to overcome is finding out what is the reading that the ECU sees before it starts pulling timing, and then get a resistor equal to that so i will know exactly when im getting timing pulled due to to much knock.
Anyone have a clue where i could get this information?
2006 Black Cobalt SS Supercharged G85
13.91@102.77
http://www.aeroforcetech.com/
This is what you want. It is basically a mini- scan tool but in the configuration of a gauge. A few of us have been demoing this unit and it is great if you are scan tool savy. Lots of useful info to include knock retard which by the way is pretty much always what we have it showing along with intake air temp. You can set it up to show whatever you want though. This is how a few of us are monitoring the knock retard. You may think its pricy but dude really if you think about it its not at all for what you get. I mean you can even clear codes with it. It's VERY useful. The simplicity is a huge factor also. Straight plug and play. Not to mention you can use it on ANY vehicle w/ OBD II
In my opinion this is what you want and then some without all the trouble
ASE Master Certified Automotive Technician
In order to get an LED to light off of a Piezo crystal, you will need a charge amp of some sort because the crystal only produces a couple of milli volts. Then you would have to come up with a sensitivity range on the voltage scale that makes sence. But still then the light would only go from dim to lighter. And then what would the intensity of the light really mean? It knocks. Scan tools have a knock count that is a good tool. But, they have all this stuff in them and that is why they are so expencive.
Hook a voltmeter up to it.
multimeter wouldnt work they do not refresh fast enough to be of any use for such a thing. The best way to go is by scan data. If using a stock ecu thats the way to go. LED isnt practical and a multi meter of any expense is not fast enough unless it has oscilloscope capabilities and nobody here would be willing to spend that much. That gauge I posted is the best economical and practical way to get the data you desire.
ASE Master Certified Automotive Technician
I had enough detonation to melt a piston, and didn't see the MIL lamp light up once...
fortune cookie say:
better a delay than a disaster.
