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Another wasted spark thread

Wesdunns70t5m

New member
Joined
Oct 4, 2016
Location
Jacksonville, NC
Hello out there in TB land. Quick question/problem about the popular wasted spark conversion. The car in question is my 1990 765, of course with lh2.4.

I ordered the Buchka wasted spark board from the CFloMoTo website and it promptly arrived. Today I finally mustered the courage to actually solder on the teeny board, and inside my ezk (with tlao chip)

I have all the components to finalize the install, but I?m working out the mounting point for the coil and igniter. Today was pretty much wiring up everything, running wires out of the ezk etc. now although my car is currently an auto, I?m still wanting to use the launch control feature, as a future manual swap would be nice/ might happen I got everything completed, including a momentary switch for the ?set?, and a regular toggle switch for the ?arm?. This is when my problems arrived...

I tried testing the launch control at a modest 1200 rpm just to see if it worked or not, which of course it didn?t. Out comes the trusty voltmeter. At first I was thinking I didn?t solder something correctly so I checked the 1-4 and 2-3 wires, and found something strange. Both wires were fluctuating between 0-1vdc. I assume that these wires should have 5v at all times, or maybe even rhythmically between the two. Just for ****s and grins I checked the wires coming from the set and arm pins, and surprisingly found a constant 5v on both of those. Does anyone know where I screwed this up at...if anything is screwed up. I?m horrible with electronics, but something doesn?t seem right with the 1-4 and 2-3 wires. Will the launch control even work without the igniter and coil pack hooked up?

Thanks in advanced, fellow brickers, for probably bailing me out yet again!
 
Anyone got any advice on this? I’m getting ready to tear back into the ezk and check my soldering. I emailed the company I purchased it from this morning but haven’t heard back yet
 
So I tested the pins on the wasted spark board itself. Arm, set, and 5v pins are all showing a constant 5 volts. The VR pin is showing a constant 3v. Spark has 0, and 1-4 and 2-3 are mainly showing 0, with a random blip of 1v.

I used 20 gauge wire from the wasted spark board to inside the ezk, and 16 gauge running out of the box. Still no email back
 
Ahhh gotcha. No such thing as a dumb question. I’m still running the distributor right now until I figure out mounting of the coil and igniter. The two logic level outputs are just wire nutted separately, to keep from grounding out on anything, which at this point wouldn’t even happen. Maybe everything will be OK if I hook up the igniter to the logic level outputs and ground wire?
 
what you're seeing as a "random blip of 1v" is in fact a 5v pulse that occurs once per revolution, with a duration of something like 3-6 milliseconds (about 1/200 of a second). It's way too fast for a multimeter to catch accurately, which is why you see occasional random blips.

Launch control etc will not work unless you're running the car on wasted spark driven by the Buchka board. If you're still on the distributor it does nothing.
 
Launch control etc will not work unless you're running the car on wasted spark driven by the Buchka board. If you're still on the distributor it does nothing.

This. Simply installing the board and running the stock distri does absolutely nothing. Although it does provide a backup if you have a mishap with bad wiring on logic outputs or your coil fails.

Complete the install and fire your plugs from the pack, your launch control should work.
 
Awesome, thank you all so much! I wasn’t sure if it would work or not without the rest of it hooked up. Should I be worried about the VR showing 3v, and spark showing 0v, or should I shut up and finish the install? Lol

I grabbed the coil packs and mounting bracket off a 99 Land Rover. Turns out once you remove the second coil pack, you can run one of the bolts through the mounting point of the igniter to thread out the (brass?) part, and mount that on the same bracket. I’m thinking passenger side strut tower for the time being
 
Should I be worried about the VR showing 3v, and spark showing 0v, or should I shut up and finish the install?

A multimeter isn't fast enough to "see" what's actually going on. You'd need an oscilloscope to see the truth, but the quoted numbers seem within reason, so I think you're fine.

I grabbed the coil packs and mounting bracket off a 99 Land Rover.

Same one I'm using on my car (albeit on a standalone ECU, not on a Buchka), and it works great.
 
Sorry I wasn't able to respond last night, but I did get basically the same feedback from Karl that mck1117 provided here. You should complete the installation, test functionality, then let us know if there's any problem. One thing to keep in mind is that the 1-4 and 2-3 output pins were swapped on the current batch of boards. So just account for that in your wiring and you'll be fine.
 
Sorry I wasn't able to respond last night, but I did get basically the same feedback from Karl that mck1117 provided here. You should complete the installation, test functionality, then let us know if there's any problem. One thing to keep in mind is that the 1-4 and 2-3 output pins were swapped on the current batch of boards. So just account for that in your wiring and you'll be fine.

Sweet to hear! I should be able to get everything else all installed today after work, we?ll see how it goes. I appreciate the help from you and everyone else. I?ll post back with the results, which I?m sure will be fine
 
So after a couple hiccups on my end...she runs! I had originally ran the middle wire of the coil to ground (I thought my memory of the wiring I looked at a hundred times was right). Of course she wouldn’t run so I swapped the plug wires around and still nothing. Checked the diagram, fixed that uhoh, and she tried starting but wasn’t quite there. Switched the plug wires and she runs like a charm! It seems like it was pulling just as hard at 80-90 as it did before the conversion at 60-70! Much smoother while at idle, accelerating, and cruising! Launch control works too!! Just gotta go back and solder the 4 wires I’ve got wire nutted together, and install the dummy coil!
 
So just a little follow up as I tidy up my install, as I figured someone out there might find it useful

Firstly, I wanted to hook up the launch control to the brake pedal (automatic). I still utilize a switch in line with the brake pedal. I figured that I’d have to run the “out” wire from the dash switch to the brake switch wire that gets energized when you depress the brake pedal. Well this resulted in the opposite of what I was expecting. Launch control would work without the brake depressed but wouldn’t work with it applied. To hook up the launch control to the brake switch, tie into the wire that has a constant 12v (yellow and green in my case)

Secondly (and more importantly) to get suh-weet TB flames, my car does the most banging between 1500 and 2000 rpm. I don’t built much boost at these levels, but after a few bang bangs I launched and instantly got sideways...I’m impressed to say the least
 
One thing to keep in mind is that the 1-4 and 2-3 output pins were swapped on the current batch of boards.
Wow...good info. I ordered mine 27th November (sent to me 14th December), is this one affected as well?
So it means 1-4 is actually 2-3 and vice versa?
 
Wow...good info. I ordered mine 27th November (sent to me 14th December), is this one affected as well?
So it means 1-4 is actually 2-3 and vice versa?

More than likely as that?s around when I ordered mine. Just hook it up, and if it doesn?t start switch the #1 plug wire with #2, and #3 with #4. That?s what I had to do with mine
 
Wow...good info. I ordered mine 27th November (sent to me 14th December), is this one affected as well?
So it means 1-4 is actually 2-3 and vice versa?

Yes, it's the entire huge batch that I've been selling for the past 2 years that's affected. Sorry for the confusion. I posted some notes in bold on the website in hopes that people wouldn't miss it.
 
Hi, as usual I am coming late to the "wasted spark party",
I am trying to find the source code for the bucka wasted spark atmega with prototype rev limiter.
So far I have found only very early source.
Anyone got a copy or a web location please.
 
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