need help from someone who knows about car computer stuff. i am trying to hook up a GM knock sensor that screws in the block to a dash board light bulb so when motors pings the light will come one i tryed this using the sensor as a ground for the light bulb and powering the bulb from the fuse box but it will not work this way. yeh a know you can see detonation when reading the plugs but at what rpm?? maybe i'm going deaf also can't hear much with side pipes and no side windows any ideas?? john
I don't know exactly how the GM systems work, but speaking generally, there's lots of computer processing downstream of most knock sensors--it's not an on/off kinda device that closes up like a switch when it detects knock. Most knock sensors are accelerometer-type devices that pick up the block vibrations. There are all sorts of algorithms running inside the ECU that process the incoming signal and then count up the number of knock-like events over time. (Misfire detection is probably the most complicated routine running on a car's ECU.) Once the counter hits a certain value in a given time window, it calls it a knock. It may retards spark a degree or two, and then look at the sensor values again, or it may set a MALF/MIL code. Some systems adapt more than others--the better systems for premium fuel vehicles run contionuously, updating the spark advance, but simple ones run just to detect knock/misfire for OBD purposes.
you need some type of amplifier to be able to use a knock sensor...it puts out a very weak signal, it's not an on/off switch. Summit sells one, not cheap, but apparently it works.
I think MSD may sell a rig based on this stuff--a look at their catalog might tell you how complex this would be. Stuff like your noisy exhaust, solid lifters, general old car racket might well confuse the thing anyhow.
The knock sensor actually picks up vibrations it feels in the block. If you put it out on a stem it won't work correct.
I have run the coupe with the plugs open. The knock sensor is mounted near the lead off pipe. I saw no change in the way the car ran. Car was way to loud for an old guy and I have not opend them up in ages, Wish I had saved that money. Guess I don't see a reason for a light on the dash to see if the knock sensor is working. If you want to hear the engine knock pull the sensor wire. I think if the engine is in tune you want hear the knock much anyway.
caspers electronics sells a kit that alot of turbo buick guys use. Try going over to turbobuick.com and see what you can dig up over there on how it all works. I do know it will pick up rattles and such, I had a bad motor mount in my grand national and it would throw off the knock sensor and then retard my timing when I would get on it. It took me a while to figure that one out.
Sir, maybe this will help, www.upscaleautomotive.com, look at the TurboXS Universal KnockLite w/ Bosch Knock Sensor, has a mode to function as a shift-lite also, hope that helps, TR
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