Terrh

iTrader: (7)

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.

distr0

iTrader: (1)

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

distr0

iTrader: (1)

... 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

j9fd3s

iTrader: (3)

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

distr0

iTrader: (1)

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?

dguy

iTrader: (8)

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.

Nosferatu

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.

peejay

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.

distr0

iTrader: (1)

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.