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Megasquirt MS3X install, only spark on 2 cylinders.
Okay so after 3 days of troubleshooting I'm finally at a loss. I've installed the megasquirt 3 with MS3X expansion card from diyautotune, this one here -https://www.diyautotune.com/product/megasquirt-iii-w-pcb-v3-0-unassembled-kit-with-black-case/
It's built, wired, and all the readings appear to be coming through correctly in tuner studio. The car starts up, however it is only firing on cylinders 1 & 4. Testing the spark output with tuner studio gave me no spark on 2 & 3 and when I switched the output pins from the MS3, the same plugs were sparking (1&4), indicating to me that both spark signals from the ECU are fine. I assumed what must be left was that I fried the ignition coil for cylinder 2&3 somewhere along the way, and went out and bought a new one only to discover it changed nothing and the car still wouldn't send a spark to 2&3, running, or in test mode.
Does anyone have any experience with this or have any idea where/why the signal is seemingly not making it to the plugs? I've also swapped plug wires to test the wires and plugs as well which also seem to be okay, so as far as I know, the problem seems to be between the coils and the stock ECU connector?
The car is a '92 1.6L
only mods are
intake with GM open element IAT sensor to replace airbox and MAF
Innovate LC-2 wideband sensor
MS3x ECU with DIYBOB
I have
(Spark A) MS3X pin 14 - Harness pin 1G
(Spark B) MS3X pin 33 - Harness pin 1H
I followed this, aside from reading somewhere that the Crank in should be... 24 I believe it was? (I'm at work now so I don't have the board in front of me. And the 2 wires marked with the * I don't have either, as I haven't touched the stock TPS. Main pin 22 is grounded with a 1k resistor to pin 8 (again if memory serves me well) for that. Last difference is a 1k resistor from Main pin 24 to 26 as per DIYautotunes instructions here. therhttps://www.diyautotune.com/support/tech/install/mazda/megasquirt-your-miata/
Other than that the wiring is the same as this picture, and no other pins are used.
Also, seeing the link in your signature, it looks like the kind of guide I've been looking for since I started this whole thing. The DIYautotune instructions were a little less specific than I expected, and I wound up googling a lot of Miata specific things and not following one single set of instructions. So tomorrow I'm going to go through all your instructions and make sure everything matches exactly, from the main board to tuner studio. I'm optimistic that following those will get things running smoothly.
After following those instructions and still getting nowhere, I decided to put it back to stock in the meantime. Stock ECU, MAF sensor and O2 sensor back in, it's still not sparking on 2&3
To test the could I switched the wiring in the coilpack and it sparks on 2&3 instead of 1&4 so everything from the coils down works fine. The car ran fine before I took anything out so the stock ECU should also be fine as it's been sitting on the bench since I took it out.
So now I'm back to square 1 and I assume the signal is lost between the ECU and coils. Could I have fried the ignition control module in the install? I don't know of anything else in the signal path so I guess I'll try picking up a new one when I return the coils I bought.
Last edited by WadeWilson; 09-07-2017 at 05:27 PM.
Reason: typo
I'm certain I fried/broke/disconnected something, it ran fine before. I just want to make sure I know what's broken where and can test it before I head back to the auto parts store and swap things on a guess. (a relatively uneducated guess on my part)
Feel pretty in over my head at this point. I learned a lot in the process which I was looking forward to, but the biggest thing I learned is that I don't know what I'm doing lol.
you can test the ignitor operation with a DMM. You can disconnect the coilpack from it, and see both the 5v trigger signals are still getting to it. Is your Tachometer still working at all?
Last time I had it running (on 2 cylinders) it seemed like the tach was half of what it should should be. I assumed that was because I wasn't getting a spark. As I understand it the tach gets its signal from the coils? I found a new ignitor on eBay for like $20 so I'm willing to risk that much to swap it out.
09-05-2017, 04:36 PM
Megasquirt MS3X install, only spark on 2 cylinders.
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