MK1 1.6 1993 Megasquirt 2.5 COP install troubles!
 

Hey everybody,

Haven't posted for a while on my build thread but I've just recently got a garage again so I can continue my build, well... until my COP conversion gave me troubles that is!

So I was hoping some could help me figure out what is going wrong as I'm getting no spark at all on two different sets of Toyota Celica 1.8 COPS.

I have 12v, ground, tacho and Trigger all wired up as needed and I've triple if not more checked them, if I give the trigger wires 12vs they fire nicely so we can confirm the other wires are correct?

I've checked the resistance and everything is as you would expect and the cops do have a separate earth on the head to be sure also.

Here is where it gets interesting, I have the spark output on my Megasquirt set to "Going high" which gives a continue 5v on the trigger wires as expected all the way to the plugs for the COPS, brilliant that what I need to make them work!

BUUUUUUUUUUUUUTTTTTT, soon as I connect the coil over plugs the trigger wire loses voltage all the way to 0.6 volts if I have 2/2 on 1 trigger wire and if I connect 1/2 to a single trigger wire I end up with 1.2-1.3 volts....

Pretty sure the voltage isn't suppose to drop unless the ECU grounds the trigger circuit, so what is going on? I don't have a 1k ohm resistor on my tacho wires but that is irrelevant to the trigger wires correct?

Does anyone have any sort of idea of what I can test or settings I may need to change as the car worked fine beforehand using the stock setup with the igniter etc.

Any help would be greatly appreciated, I'm pulling my hair out currently hah!

1 thread wouldn't do it?

Thought this would be a better place to post it, my bad!

youre going to blow your coils and MS with your tests...

Any suggestions on methods I can use to better test and find out the cause?

Mind posting the diagram you used for the wiring? I had some issues with some 1.6 COPs not too long ago. Found it to be a mismatch between my tune, and the way my MS was built. My issues sound different, but it might help. Thread: https://www.miataturbo.net/diy-turbo...o-start-92101/

I used this thread: https://www.miataturbo.net/useful-sa...writeup-12704/

The only thing I have not installed is the resistor, however, this shouldn't prevent me from getting spark only tach I would have thought?

Also by the looks of things you fixed yours by changing your spark output to going high? or is that different?

Would you mind checking the voltage you have on your trigger wires if it staying at a constant 5 volts?

Same thread I used, and I must have gone through it no less than 20 times while tacking down my issue.

I put the resistor in as cheap insurance when i was doing my troubleshooting.

Mine was fixed by setting the spark to going high.

Ill get input voltages tonight, but here are some pictures of my board (Im just now realizing that I may have mis read the title, and these may be of no use to you, but none the less):

https://farm5.staticflickr.com/4164/...075f038b_c.jpg
20170210_194252 by Tyler Swann, on Flickr

https://farm3.staticflickr.com/2850/...45d732bc_c.jpg
20170210_194304 by Tyler Swann, on Flickr


What seems to be a silly question, but was your car running prior to the install? For what its worth, I was running fine NA, but started experiencing what I thought to be spark blowout after going FI. Hence my going to COPs.

Thanks for the pictures I'll compare them to mine later this evening, the car was running fine prior on stock coil packs and I even tested running on a another set of COPS which came off a functional COP conversion car its very odd. I think at this point I have no other choice than to buy an igniter and see if that still works on stock setup.

Double post...

you gutted a good ignitor to go cops?

Yeah I had to, I did originally buy a spare and gutted that but when I moved house it was one of the things that got lost in various boxes :/

Could it be my earth as it shared with another on the head by the intake side rear engine hook causing the low voltage when the cops are connected?

There's nothing special here about a cop harness. you connect a few wires to the coils via the gutted ignitor. You didn't need to make any changes to the MS (except for dwell settings).

If it's not working, I'm assuming you wired it wrong.

all (4) coils share the same ground, +12v, and tach output, via the ignitor.
that leaves you with batch wiring the (2) spark outputs between the (4) coils. Where 1/4 and 2/3 share them...

Well I've checked all the connections making sure they are correct numerous times, I even doubted my self and thought I had tacho and trigger backwards but after checking your thread and a few others I have actually got it correct.

Can you confirm if I should have 5v on the trigger? and is there anything I can do to get some sort of idea what could be wrong, I have a multimeter etc

depends on your spark outputs, if youll see 5v all the time or not.

Well originally it was sett to going low on the spark outputs when running stock setup, however I have set it to going high for the cops I guess It needs to be going low since that's what worked for the original setup.

correct. its possible you could have damaged the coils running them "going high" when your spark outputs didn't match.

Hmm okay, I'll swap the settings over tonight and try again on both sets I have. Is it possible my coils are 12v trigger rather than 5v? as they most certainly still work if I give them 12v which is what baffled me.

Thank you for your help so far, I've been stressing about this for a while now.

Should be worth it in the end though got my GTX 1.6 cam cover fitted, cop adapter plate and the cops and even though it don't work it looks pretty at least haha!

I did this pretty recently myself and I left output the same as Brain mentioned other than dwell settings. My car is a 91 with vvt swap. I was able to run without the resistor in diagnostic box, just no tach signal on the dash.

One thing that i did have happen was on the gutted ignitor is that one of the signal wires was shorting to the body when i secured the ignitor and would only run on 2 cyl, apparently i didnt insulate it well enough at first. anyway my point is make sure you dont have something similar and of course double check your wiring. I followed that same thread and mine started on the first turn of the key(short happened after the first drive bc i hadnt secured the harness yet)

I tested the coils on the spark output going low and still no spark, even on test mode. It may be worth noting I didn't change the spark mode till a while after testing the coils how the original setup was and they never worked then either.

Really at a loss to why it's not working.