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Discussion Starter · #1 · (Edited)
This thread got me to thinking again about knock sensors. They detect detonation/pinging, in a computerized car they tell the ECM to back off the timing a bit, to keep it simple...
An old tuning trick is to time an engine by ear, generally you want the most timing advance as possible without pinging.
But, how would you hear it in a race car? And how do you know what to set the timing at initially for best performance?
A knock sensor. How about one that just detects it and then tells you there is detonation occurring in your $XXXX engine? It wouldn't have to actually adjust anything like on the computerized systems...
Gee, what a great idea, I thought. So, how do we make one?
It didn't take a lot of research to discover that it's been done, all the Radio Shack part numbers and full instructions have been printed out. How convenient! Quite simple, too, even though I'm not exactly an electronics whiz.
So, who out there is an electronics whiz and could whip one out for me? The picture attached shows that it really is quite simple.
 

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Jeff, this is kinda coincidental, I was on the phone yesterday to a VDO repair shop trying to get a fitting for my oil pressure transmitter and we were talking about converting the electrical speedo drive to a mechanical setup, and the discussion got around to the various sensors on the V-6. When I mentioned knock sensor, he said, "Yeah, it's just a microphone that sends impulses to the computer". O.K. so I'm gullible, but it makes some sense, I guess.

Anyway, if you can point me in the direction of the schematic and parts list, I've got a RadShak nearby, I can kinda sorta read a schematic and I've got a couple of soldering irons, along with a couple of spools of real thin solder from my USAF days. And because I'm retarded, and the GT is in the body shop, time is for the most part, my own, except for the dog shows Margaret enters.
 

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Discussion Starter · #3 ·
Ron, the research first started hitting home at
http:/home.netcom.com/~bsundahl/knock/listen/listen.htm
It was on the right track and very interesting but not quite what I needed, so kept searching and this came up
http:/www.gmcmhphotos.com/gallery/showpic.php?aid=59&uuid=mrerf&aid=59
Bingo. And then later up came a kit with a knock gauge that is really neat but is more of a permanent installation, it is called "casper's knock guage kit"
http:/www.pfyc.com/store/merchant.mv?Screen=PROD&Store_Code=PFYC&Product_C...
Boy that was a mouthful, did you get all that?
If you want to build one of these for me I'd gladly pay you for your expenses and efforts, you'll probably want one too, and I'm sure others will. I'm sure you need something to do between cleaning out Margaret's garage and walking the dog...
Thanks!
 

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Jeff, I tried to get to each of the urls you posted and I couldn't get to any of them, well, change that, I didn't try the first one, but the 2nd and 3rd were not complete. I even tried to go to the base url and run a search on those sites, but that proved to be futile as well. Actually, the V-6 already has the sensor installed, and all the sensors, etc., to go with the computer controlled system, so I don't really need to build one for me. I just think it would be an excercise in fun to try and build one, then let you test it for grins and giggles to see if it functions as advertised or if it goes the way of the 100 mpg Fish Carb. Yeah I'm that old, I remember those. Any way, if you can e-mail me with attached instructions, parts list, and schematic, I'd be more than happy to try and build one. If the cost for parts isn't way outa site renumeration is not that important. I'm in just for the "can it be done" and "willit work".
 

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Well, it's in the works, got all the parts, set up my lighted magnifying glass, soldering irons, etc. I got most of the components soldered on the board after reading and rereading the instructions. I've got to install all the jumpers and then assemble the whole mess in the box with the bells, lights switches, and whistles. I had to take a break for a two day dog show, today and probably tomorrow, I'll spend most of my retarded time on a motorhome from across the street, he had a blow-out and took out the wiring harness in the wheel-well. It's the neighborly thing to do you understand. :rolleyes:

I'll get the board finished ASAP after that, Margaret wants my stuff off the dinette table from our motorhome cleaned up in the living room. It just happens to be next to a large window with good light. :D

BTW, Happy Birthday Jeff
 

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Discussion Starter · #7 ·
Right on, Ron! That's great!!
And thank you, it has been a great birthday. There's nothing like opening your lunchbox and finding a handmade birthday card from an adorable nine year old!
And having a very promising job interview right after work!
My birthday gift was a shiny new BIG bottle of ... argon/CO2 welding gas. Hooray, I can get back to work on the trailer which will haul Speedway GT around on. :cool:
 

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Jeff, here's the latest on the knock sensor. I got the last, I think, of the jumpers on the board, now, to hook up the LED, switch, buzzer and buzzer off button. Then I'll jumper it to my V-6 sensor to see if it works. I hope, I hope. Margaret has been kinda neat about me building it on the motorhome dinette table. It's in the living room, where it resides when we have dog crates in the big rig for dog shows. When I got all the parts at RadShak, I had to get multiple packs, you can't just get one of anymore, so I've got a gazillion extra pieces of the parts. Here's a pic of my "work station" to give you an idea of what I mean. Oh, yeah, the circuit board is in the black box below the RadShak bag.
 

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Discussion Starter · #9 ·
Awesome! I hope it has been a fun project, were I to attempt something like that I would get very frustrated quickly. Electronics just isn't my bag!
Once you hook up to a knock sensor, you should be able to just tap on the block and see results, even with the engine shut off. At an Indmar boat engine class years ago we were shown this trick, while watching the timing marks with a timing light, engine idling, just a couple taps on the side of the block sent the timing down three degrees instantly, then within seconds it would come back up.
With your knock sensor disconnected from the vehicle harness, don't turn the ignition on, the computer will see the knock sensor missing and set a fault code... learned this at the school of hard knocks, that sensor has to be working for the engine to run right!!
Thank you for all your effort, and thanks to Margaret for her tolerance!
 

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Jeff, I'll run one of my 12V ni-cad battery packs to power the box. The engine is still on the dolley waiting for the car to get back from the body shop (tomorrow), the computer for the engine is still in the box with the modified wiring harness, so it won't even see a malfunction to load in memory. All I want to do is smack the engine block near the sensor with a ball pein hammer and see if the buzzer goes off and the lite comes on. If that happens it will be heading your way. If not, then it's back to the drawing boards and instructions to find out why. BTW, Margaret asked tonite when I was gonna be done with it. She wants my "crap" off the table. Don't know why she said that, we don't have anything planned for the rig this month. No sense of humor. :D
 

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Darn, just looked and it's been two weeks since I last said anything about the knock sensor. Well, I got it all built, hooked it up to the V-6 and a ni-cad battery, the lite came on, the buzzer came on and neither would go off, and I hadn't even smacked the motor yet. So I disconnected everything and went back to the plans/instructions to find out if I screwed up something. While I was mulling things over in my mind, it finally hit me. I didn't have the engine grounded to the battery, gotta have a completed circuit. So I hooked everything up again, but in my haste, I hooked up the ground jumper for the engine to the positive side of the battery. Something went POP inside the box and nothing happened or worked. I guess I lost the magic smoke, although I didn't see any escaping. So I'll head back to RadShak and pick up some more stuff and do a rebuild. I just kinda left things as they were after I figured out my screw-up. :mad:
 

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Discussion Starter · #12 ·
Well that sounds like something I would do... By all means, don't fret it, there is no hurry! We won't be firing up race cars for another month and a half yet. Besides you've got plenty to do, I've been following your "willit" thread, I want to see your GT done as badly as you do!! :)
 

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Yeah Jeff, every one wants to see it done, even the UPS driver. I'll rebuild the sensor board next week, the GT is going back to the body shop for final exterior paint and clear coat, then to the upholsterers, then I get to put it all back together. Oh Boy, Pure Joy. :D
 

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Well, here's the straight scoop on the Knock Sensor. Either I screwed up on a completely new build or the schematic is wrong somewhere. I can't tell about the schematic, I'm just a mech with some soldering skills, not an electrical engineer. Sorry Jeff, but building two boards and both not working isn't my idea of fun anymore. Maybe someone can look at the schematic and find out if it is a feasible schematic. If so, then I must have screwed up somewhere building it. The darn thing turns on the LED and buzzer but will not turn off. Well let me clarify that, when I hook it up to the knock sensor on my engine it sounds off and lites up. If I disconnect the sensor wire it goes off. Maybe I have a bad sensor. I'll check it out, I've got a new one somewhere in the garage. I'll search for it and try again when I find it.
 

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Jeff I've got the box and extra parts in a bag so that, when I find the new sensor I bought for the V-6, I can check it with everything new. It just bugs me that, either I screwed up or the schematic isn't quite right. The reason it bugs me, is I built a smaller board replacing the Theft Deterrant Module on the engine and that fool thing worked. I needed it to get the V-6 to run on the stand after I got it. I'll let you know if it works after I find the new sensor.
 

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One thing to note is that some motors will put the knock sensor "microphone" in somewhere in the water jackets. The liquid coolant mutes errant noises and amplifies knock related noises. Just a note for anybody thinking about this, which does sound like a decent idea. Also note that a lot of racers and hi-po tuners desensitize or even disable knock sensors in late model cars.
 
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