How to wire inductive pick-up?
 

Here's a link to download the pictures and files to better understand my situation. It was too big to just attach it as a file on here.

https://www.mediafire.com/?sharekey=6...fc4b85d405c0ff

Alright, I got a few questions if anybody can help. I ordered an inductive pick-up off of ebay. I clipped it to the spark plug wire, and I wired the other to a microphone jack with a 50k potentiometer in between. I can't get the street dyno program to work right though. I put in my WAVE file and my configuration file and hit the start button but i get the message "Invalid Floating Point Operation". Then if I click the start button again it says "Floating Point Division by Zero". I'm pretty sure I have all the stats filled out so I don't know why it says floating point devision by zero.

I think it may have something to do with it how I have the inductive-pick up hooked up. I'll attach the audacity files of my three runs. I'll also attach a the audacity file of the sample run (that came with the program) that works. You can tell a distinct difference in the how my wave files look compared to the sample wave. I'll also attach a picture of my set-up on my car. Does anyone have any ideas of why my WAVE files look so different? I believe this is where the problem is.

Any help would be greatly appreciated.

Might be inverted input, flip the pickup on the wire and try again.

I put the pick-up has a side that says "Spark Plug Side" and I put it on according to that. But it is used so it may have broke at some point and someone repaired it but switched some wires around backwards. I'll try flipping it, hopefully it works.

Well that's a fix for if you wired it crossed to the jack. (Or have the audio header in the computer on backwards or something)

I tried it backwards, same results. I also tried it on my dad's single-cylinder Wildfire Truck. The wave file was a lot closer to the sample file than the wave file from my Chevy Lumina. I think it may be detecting the spark from some of the other cylinders on my Lumina. I got it to put out a dyno graph from one of my runs on the old version of Street Dyno 0.6.0, but it was way off, only went up to 2000RPM, and said peak horsepower was 4 when the graph showed 100 at 2000 before it cut off. I tried some other WAVE files from my other runs but the program decided not to work anymore.

I think most people go with the method where you use the negative terminal on the ignition coil, however I'd really like to get the inductive pick-up working So I can use it on some of my families newer vehicles with multiple coils, such as my Lumina. It'd also be a lot faster to switch between vehicles with inductive pick-ups. I don't think there is a way to wire it into the coils negative terminal on the new muti-coil setup, not easily at least.

Hmmm, don't have a "wasted spark" system on that do you? Meaning you get a spark during the exhaust cycle as well.

Hmm, I hooked it up to my '87 Civic today (distributor ignition). It put out a similar graph as my Lumina. I also downloaded the trail of PowerDyn and used the Tachometer feature (in real time, not with a wave file). I set it at 2 sparks per revolution and 35 trigger high. and it was showing the same RPMs as the tach in my car. So, I'd assume that its also sparking during the exhaust stroke. Since the graph is similar to that of my Lumina, I'd also say that its sparking during the exhaust stroke.

Street Dyno doesn't have a sparks per revolution input, however Home Dyno and Road Dyno do. Home Dyno being the free one, I hope I can get my hands on it.

I also noticed that it liked whenever the wire was under the hood the PowerDyn tach would jump around, probably picking up some of the spark from the other wires. So I'll probably have to find some RF shielding foil or something of the sort to surround the wire to wipe out the interference.

Or you could rewire it with coax, vehicle ground to the outer sheath.

I just got done wiring up some coax instead of the extension cord wire I had before. and I took the RF chokes out, i figure they didn't help much and may even be choking the one spark signal its supposed to detect. I'll test it out tommorw, hopefully I'll get a cleaner signal. then on to the problem of the wasted spark ignition system.

They coax helped cut down on the interference by a lot. I've been using the tachometer feature of PowerDyn to check for interference, I watch how much it jumps around. There is still slight interferance, I figure this is from the inductive pick-up since there is no insulation around it, just a plastic cover. I'm going to wrap some aluminum foil around it and hope this keeps the last little bit out.