<p>&nbsp;</p><p>Is there a fuse or other easy-to-get-to component for disconnecting primaries of Stock '99 coils during ECU FW updates?</p><p>Or must I pull the connectors from the cois?</p><p>(In truth, I have upgraded FW 2 times and done nothing, but this sounds risky).</p><p>Reference: MS3 Basic</p>

 

unplug the 2 plugs to the coils in the back
isn't that already super easy?

 

<p>Check with Rev but I bet you don't have to disconnect them. I know on MS3x you don't have to. Its leftover from the spark inverted days.</p><p>Paging @Joe Perez but from what I remember when you have to run spark inverted then it means the drivers are set up in such a way that the coils are fired by driving the output pin high, and pulled low when not firing. So when you flash firmware the pins can be left in a floating state and the coils will be stuck on.</p><p>&nbsp;</p><p>TL;DR;</p><p>If you have to set your spark output to inverted, then unplug coils. Otherwise it don't matter.</p>

 

It's all about the output circuit.

In the traditional spark-output circuit (the one based on LED 14 and 16 that we've all been told to use by old farts even since before DIYAutoTune came on the scene and codified it in documentation), the output wants to be on at all times, and the CPU has to forcibly turn it off.

This, of course, causes bad things to happen when the CPU is unable to do so, such as when it's inactive. When the CPU is inactive, its driver pins float at high-impedance (what EE folks call going tri-state.) Normally, this causes only an annoying little backfire at turn-on for those folks with leaky injectors. But during a reflash, the CPU is inactive for a long period of time, and this can burn coils.

So for ECUs built on the old 3.0 / 3.57 (all MS1 and MS2, and some MS3), you can do the "JoeSpark" mod to de-invert the output driver, thus eliminating the power-on spark and also making it safe to re-flash with the coils connected.

I can't speak to the MS3 / 3X, as those inbred, child molesting, Satan worshiping, donkey raping ****-eaters who call themselves Bruce Bowling & Al Grippo have heartlessly and callously decided not to allow us mere mortals to view the schematic for the MS3 CPU module (and have provided only a uselessly low-res copy of the schematics for the 3X board), and thus, I have utterly no idea how they're driving them.

 

Thank you for translating my redneck EE to proper California tech writing standards. I got my degree in a farm town.
<br />If I'm feeling frisky I'll dig into the source code and tell you what they set the pins to. That will tell us what the circuit is doing.

 

I fried 2 coils while using my ms3 basic. I believe it was from flashing firmware because it happened at the same exact time I did that... however I have no proof and It very well could have been from me shorting something.

 

<p>Paging @Reverant</p>

 

The ms3 basic does not require you to unplug coils during a firmware update.

 

<p>Thanks to all. 18, yes, I am that lazy. Aidan, I'm glad I was able to give you something to focus on. Joe, nice rant. Rev, concise reply.&nbsp;</p>