No spark while running, but spark when initializing MS1
 

1991 1.6L
MS1 HiRes
Standard LED-> ignition mods

Just finished a COP conversion with 1zz coils.

I finished my COP conversion, car ran fine upon an initial test. Then, when buttoning everything up I think I shorted the 1&4 control wire to +12V for more than a few seconds. Now the car will only run on cylinders 2&3.

I have verified only 2&3 are running by disconnecting the coils while the car is running.

I have swapped coils around to show that none of them are dead.

I get visible spark on 1 and 4 when the ECU is turned on, but none when it is running. I pulled a coil and put a spare plug in it, I see spark when the ecu turns on, but none when it's running, with no configuration changes.

I poked around in my MS1 with a multi-meter to check out the transistors, but couldn't find anything wrong. Not that I am an expert in checking such things...

I took out the plugs, cleaned them (though they looked decent), and put them back in.


I am totally at a loss for what to do or what could be causing this... any thoughts?

Replaced CAS with presumed good one, no change.

Please post a copy of your MSQ.

Will do as soon as I get home. Or I may run home for lunch just to grab a copy...

Here is my MSQ and pictures of my MS board. I see that I have 1k pull-up resistors for the ignition drivers, I will try replacing them with 100-ohm resistors right now.

https://www.miataturbo.net/attachmen...ine=1375911426

https://www.miataturbo.net/attachmen...ine=1375911426

https://www.miataturbo.net/attachmen...ine=1375911426

The inboard-most LED lights up nice and strong, the outboard-most LED lights up VERY faintly.

Does this mean a shot transistor? I'm going to try and source a replacement...

Replaced pull-up resistors with 100ohm, no improvement. Got some transistors to try now...

I did have the LED ignition mod.

Upgraded my two pull-up resistors from 1koh to 100ohm and replaced the spark control transistor on the pair that wasn't working, it's LED was lit up VERY dimly. Now my car runs great!

The 1&4 control transistor had partly failed, still allowing spark during initialization but wasn't strong enough to power the COPs (or it's LED) when running. I've never seen anything like it before.