Yeah both rotors on mine died within a mile of each other. And lost full compression on each when the rotor died.

When I pulled the engine you could get the flywheel spinning and it would keep spinning by hand for 1/2 a second, absolutely no compression at all. Engine had *maybe* 3000KM on it. Tune was solid. Was the most fun I had in an RX-7, ~450HP and 205 wide crappy all season tires and I was still young and fearless.

 

So what happened when you took the coil off for another car, was it dead or what? My engine still runs great (as far as I know) - it just shoots a fountain of oil out

I'll go put a timing light on the trailing wires later and see what they do while cranking

 

... and do you still have your MS2? How funny would it be if you had sold it, I eventually ended up with it and it just continues killing engines

 

i think i would replace the coil, when in doubt... then re route the plug wires.
at the very least you should be checking timing on all 4 plugs, but maybe a new ecu is possible

 

I'm not sure what to make of this. This is all testing with a timing light while cranking with the fuel pump unplugged.

Coil set that was in the car originally:
T1 fires double speed. This is bad. Would explain breaking engines.
T2 fires normally
T1 visually looks like **** (crusty inside the wire terminal). T2 looks good

After swapping to a complete spare coil assembly:
T1 fires normally
T2 fires normal speed but misses intermittently

I then swapped the 'good' T2 coil from the original set to the spare set, and it STILL fires intermittently.

So are both of the coil modules bad, in different ways?

 

It's going to be - obviously - one of these three: Coils (FC coils rarely go bad in my experience, but they are getting older so we will see more failures than previous), the wiring, the controller (MS2) - Or a bit of a mixture. I know if it were me I've seen and heard of too many 'weird' intermittent issues with MS ignition controls to ignore that.

 

That original coil does sound suspect. Like j9fd3s wrote above on a logical troubleshooting sequence,Is this with the wires still zipped tied? I would try separating the wires and doing the test. You could also pull the trailing plugs, put them on the fender and take a video if your phone will run it in slow mode to see if they are firing/toggling correctly as another way of testing.

Before considering the ecu swap. Like you mentioned the car ran for 6yrs without incident.

What firmware version are you using in the MS2?
There was a firmware bug that was corrected in the most recent firmware where the trailing was firing intermittent in "FC ignition mode" if I remember correctly. I can't seem to find the post but someone scoped the signals and found that out. You should be using the latest firmware. That may or may not explain the second replacement coil firing trailing intermittently if you are a few firmware versions back.

If you haven't reloaded the firmware in yrs. you could possibly have corruption. I've seen posts before on that.

It could also possibly be a hardware issue. I would look at that more lastly.Not just the ecu, but coil grnds, wiring,etc.

Whether or not in the rebuilt engine the break was caused by not re-zeroing the timing in the ecu, I still would make a post in the megasquirt forum. If after having two engine failures doesn't get there attention and a suitable response and verifying the code.I would then consider drop-kicking the MS2 platform for something else.

 

I have had a few FC trailing coils fail over the years. The coil itself, that is, not the electronics. I drive a leading and one trailing coil with an MSD and the trailing coil goes through a distributor.

Have not lost a leading coil but the trailing coils like to find a new ground through the shell instead of the spark plug wire.

My gut feeling is, you have a computer that can do it, bite the bullet and discard the FC ignition entirely for a rack of GM coils (I forget which ones people like, D585?) or IGN-1As. It's cheaper than an engine and more reliable than the FC setup, which IMO looked like a way for Mazda to expediently hammer a rotary ignition system into a engine controller not designed for that many ignition outputs.

 

I've had no motivation to even start disassembly yet on this. 2 dead engines in 3 months sucks.

I just checked firmware versions though, looks like I'm running 3.4.2

the 3.4.3 release notes talk about trailing spark outputs: https://www.msextra.com/downloads/ms...3-4-3-release/

and 3.4.4 is the latest: https://www.msextra.com/downloads/ms...3-4-4-release/

I still need to buy or borrow a known good trailing coil and repeat my testing from last week, see if it acts odd or not. Also borrowed an oscilloscope tonight. Planning to hook that up and play around with the MS ignition test mode. Never used it before but maybe it can uncover the issue.

 

Just to update here, I sourced a new rear iron with the extra reinforced dowel area and rebuilt. Re-used everything else as it was, just the new iron and new coolant seals. It's been running strong for a few weeks now.

I had one scare with the new motor where it felt like the exact same thing happened when the iron broke. Bucked suddenly around 6-6.5k rpm. I ended up figuring out that's where my 'soft' rev limiter was set. Limit was set to 7k with a 1k hysteresis, which apparently sets a soft limit at 6k. I now think that hitting the limiter is what broke the motor. I found several other examples on the forums here where the exact same thing has happened. Not sure if it's a megasquirt think or just a rotary thing in general. Anyways, I removed the limiter and it's ran great since

 

Wow, I remember reading this a wile ago, thanks for the update. I really hope that you have some fun driving the car, it's about a year overdue.

 

What did you do with the MS2? You were having issues with the trailing coils either firing twice as fast or intermittently. Did updating the firmware solve the issue? Are you still running the stock FC coil configuration on the MS2?

 

im wondering if the cheap old timing light was throwing me off thinking the coils were firing wacky. i did replace the plugs, wires, and swapped the coils to a spare set though. tested the signals with a scope both pre and post coils and it all looks good. i ahould actually swap the old trailing coil back in and scope it as well.

 

Having the secondary firing at double speed is not good. I am running MS3, so slightly different, but it should be IGN A is running leading plugs (bottom) and they do fire fast, because they are set up in a wasted spark config. Fancy stuff with how electricity flow, it will send more power to the chamber that is compressed, and even if the other plug fires, it is during the exhaust stroke

IGN B should be the second trigger, and IGN C is the trigger to change which trailing (top) plug should be firing, so that might be the one to be looking at because both A and B are firing at the same rate, is just C is swapping on and off to change IGN B firing from front to rear plug

Make sure you are not running FD or RX8 mode on the MS2

FD has outputs wired up slightly different, and RX8 is COP with using 4 outputs so A,B, C, and D to individual coils

 

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