COPS for dummies:
The following write-up is an attempt to consolidate my experience with my conversion to COPs. It’s a fairly comprehensive accumulation of everything I did to make mine work. In the end, it really didn’t take anything to make it “work”, just fab the harness and plug it in. But it took me awhile to get everything in order and start the job. Hopefully this helps some other guys on the fence. There is going to be a certain amount of insulting your intelligence in this thread, but it’s things I screwed up, so hopefully something in here saves each of you who are going to do this a little time and effort. Here goes.
My setup is a 1.6 running Megasquirt standalone, so be sure when you make your harness, you are following the correct diagram in the first link below.
Here are some links:
The original DIY COP by Braineack in "useful saved posts:
The continuing monster COP thread in the DIY forum:
My original I Love COPs thread:
I also highly recommend you do a title search for COP and COPS and read all the most recent threads about the subject to be sure there isn’t something new that we’ve discovered.
I purchased 4x 2000 Corolla 1ZZFE COPs from a described 10k mile car. They were in perfect condition and came with the fuel injectors from the Corolla that’ I’ll try to unload on eBay. I paid $60.
I purchased 5 connectors from the source in THREAD#1. I wish I’d bought nine. During some experimentation, I hurt one of them bad and couldn’t use it. Then I didn’t really like my first wiring harness and wished I’d had 4 more to make another one and do it perfect. I recommend you buy 9 connectors. One is to screw up, and then you have enough to make 2 full harnesses.
I got my connector pins from Brain, but he’s out. You’ll need to buy yours from the source in THREAD#1. You’ll need 16pins, but I recommend you just buy 100 and you’ll have enough for 2 harnesses, plus screwups, plus you can hook a bro up who might need some local to you.
The wire I bought at RadioShack. It’s an 18 guage 3-pack. I noticed that the individual copper strands of each RED/BLACK/GREEN wire are different. The BLACK wire is just 5 or 6 heavy strands, while the red one is about 30 hair-thin strands… the GREEN one is in the middle. I used the BLACK for GROUND and TRIGGER. The RED for 12vlt, and the GREEN for TACH.
I bought a spare ignitor from a forum member. In the end, the ignitor was way more pain than it’s worth. Soldering the wires to the leads in the ignitor is a chore I wouldn’t wish on anybody. My experienced recommendation is to just solder some wire-ends onto each wire and and connect them directly to the harness, leave the damn ignitor out of the loop.
My Megasquirt standalone required a resistor to facilitate the tach signal. The best place to put it is in the DIAGNOSTICS BOX. I cover this thoroughly in THREAD#2.
To make sure you’re fab’ing the harness the proper length, I made a template on some cardboard and placed the COPS on it in the exact separation they’ll be installed. Each wire I cut and soldered I just made it the appropriate length by measuring the distance with the COPs sitting right in front of me. The distances don’t have to be down to the exact millimeter, but within ½” or so. Don’t forget to space out your splices on each wire. The last thing you want is a 1” diameter cluster of splices all in the same spot on the harness… just spread them out ½” or so, and don’t forget that the shrink-wrap will give the splice a little extra girth as well.
STEP#1: Lay out the wire and start cutting/stripping/soldering. I put all my connector pins on as I went… and made sure I when I put them on, they were already as lined up as I could make them, so I didn’t have to twist the short 1” piece of wire coming off the main harness 180* to fit into the connector right-side-up.
DON’T FORGET TO SLIDE YOUR SHRINK WRAP ON BEFORE SOLDERING!
If you’ve never soldered wire before, just practice a little. The key to soldering is that solder isn’t paint. You don’t solder over the top of the wires… you get the wire hot enough that the solder soaks into the wire and bonds each strand together. There’s a series of pictures that shows this perfectly.
STEP#2: You can actually do this well before step 1. Once you’ve got the harness fab’d up, you need to Dremel a little bit off of each pin so it’ll seat properly. Reference the pic. I wish I’d done this while they were all still all on the factory strip so I could make them all perfectly uniform. However, I waited until the harness was done and did them just holding each one in my hand while I Dremeled. Not to big a pain, but it would have been easier/faster/better to do them on the strip.
STEP#3: Pushing the pins into the connectors. They’ll only go in ONE WAY. And they’ll click in place. If you push them in as far as they’ll go and don’t hear a click, then you probably didn’t Dremel enough off. They also don’t seat very tightly once they’re in… the pins will wiggle around in the connector a bit. Also, once you put a pin in the connector, IT’S IN THERE!. And you’ll destroy the connector if you pull on it hard enough to pull it out. That’s why you buy a few extra.
STEP#4: Don’t forget the extra Ground wire. You'll want to place your harness roughly in place on top of the valve cover to see where exactly you want to splice it in. I think mine is about 6" past the #4 connector... enough room to route the harness through the brake vaccum hardline and the fuel lines. Just make the ground splice itself a foot long and trim it to perfection later.
STEP#5: Gutting the ignitor. I made 5 small holes in the back of my ignitor instead of 1 big one… made sense for the wires to come out of it as straight as possible. The middle hole was slightly bigger as it included 2 wires. But again, I recommend you skip the ignitor and just put wire-ends on.
The metal ignitor cover is on there pretty good. I didn’t drill mine as recommended, but rather put a small flat-blade screwdriver in the bolt-hole and pried one side up… then used the screwdriver along the edge. The inside of the ignitor box is covered with this jelly-like cummy sticky stuff. It sucks… and it sucks some more. There are also some metal pins that may be stuck to the cover. Just pull them off gently, you don’t need the flimsy bendy little pieces of metal stuck to the main ends. Once the little bendy pieces are pulled off, gently pry the ends up and straighten them so they’re sticking straight out… makes for easier soldering.
Then do your best soldering on the ends. It’s tough in there with the shrink wrap. You get the soldering iron close enough to it that it shrinks just a little and you may have the nip the shrunk end of the wrap to get it to slide over your connection.
It’s also recommended to Epoxy your wires inside the ignitor… I just wrapped the gutted ignitor in electrical tape seated it back down in the stock location.
STEP#6: Now that the harness is finished, test it.
Pull the spark plug wires.
Unplug the coil pack.
Unplug the ignitor.
Drop in your COPs.
Connect the harness to the COPs.
Ground the harness.
Plug in the gutted ignitor, or just slip on your wire ends.
Install resistor in Diagnostics box if necessary.
If it fires, move on…if not, troubleshoot.
I wrapped my entire harness in electrical tape… over to you how you want to finish it. I may get some plastic corrugated wire wrap to make things neat, but not this week.