HyperDrachen

'88 N/A 170k miles. The car usually doesn't do long trips. Just around town, to and from work. Recently took it for a 100 mile trip on the interstate. As the car had fresh wheels and tires on it and the best allignment ever : ) I decided to see if I'd get any vibration with increased speeds. Got up to a steady 110 before I decided to stop flirting with the law and backed it off. No vibration no complaining from the powertrain. Cruise at 80mph the remainder of the trip.

Once i got into town I noticed that the idle was a bit rough. Mycar has never had a flawless idle. Usually get at least a little sputter(only noticable in exaust note) every 10 seconds or so. But at this point there's no noticable performance issue and the car sounds fine at anything over idle. Park the car for about 20 minutes. Get back in startup is fine but idle is still steadily rough. No pinging noise or anything dramatic so far. Get back to the main road get to about 40mph with about 50% throttle and suddenly get hit with a monstrous lack of power. I pull over and as soon as it goes to idle it dies. Restarts, a little hard, but on demand. Idle is very rough. It's fairly obvious only one rotor is firing.

When the power cut in half on me there was no noise just suddenly my car had no power.

I'm stuck in the middle of nowhere at this point, I pull out the plugs. They're not new but most look fine, save the leading for the rear rotor. Kinda whitish and brown, looks fairly foul. I run a multimeter through all the plug wires, resistances are between 9 - 12, as I recall that's fine. I try diffrent combinations of plugged in wires to narrow that the front rotor is the one still kicking.

I don't actually know where to put my test leads to check my ignition coils.
I ground the leading plug for the rear rotor and crank the car (fuel injection disabled) no spark. I'm an hour from home and don't want to tow the car if i don't have to, I find a part store with the autolite plugs(no one had the ngks) for the car and sub it in for the foul plug. No change. At this point I'm suspecting the rear leading coil of being bad. But as I said I don't know where to stick my test leads on this part.

Ran out of daylight and it's ffin cold outside, finally had it towed home. I'll do compression checks tomorrow. If anyone could point me in the right direction for how to test the coils that would be great. Also any input on what might have caused the coil death, would be appreciated. As I understand it this is a rare failure. I do recall times when I would push the car a bit harder under acceleration, too much throttle and i hear the "metal popcorn sound" but in response to that I backed off the pedal a bit and it stopped. So i'm thinking maybe it took some damage to the apex seals and just finally kicked the bucket.

For reference, no smoke or odd noise if i start it right now.

HAILERS2

There is but one coil dedicated to the Lead sparkplugs. IF one lead plug fires, the other also fires....and at the same moment/time.

Compression test is going to show one rotor is bad. Rolled a apex seal probably.

You can prove this in a way. Just swap both lead wires and try again. Same results will occur.

There are indeed two trail coils.........but neither needs to fire for the car to start and run normally or idle normally.

Once again.........just one LEAD coil for the lower sparkplugs. BOTH fire at the same moment (called Wasted Spark ). There are two wires for that one coil.......and both fire at the same moment .

HyperDrachen

Both rotors power"stroke" at the same time? I need to do some reading up on the power cycle on this motor I was apparently massivly confused.

HAILERS2

No. But both lead plugs fire at the same time. One firing does NOTHING 'cause that rotor is not on the compression stroke. The other does fire 'cause it is. This is called the Wasted Spark System and it exists probably because it's cheaper to do it like this.

No harm comes from the spark that is not on the compression stroke.

I thnk the WAstd Spark system is used on many other cars. You might do a GOOGLE search on wasted spark to verify and explain that.

Might swap sparkplug wires around and see if things get better. Might be a bad wire. Not likely though.

http://www.teamfc3s.org/info/articles/demystifying.html that site is down right now but you might try it in the future 'cause that DE-MYSTIFYING the RX-7 ignition system is a good read. Bookmark it for a later day/week.

HyperDrachen

Yeah it hit me after i left for work what you ment by waste spark. I always wondered what controlled the firing order of the two sides. Not thinking about how if one fired in a pure air mixture it would be irrelevant. The plug wires are good though tested with a multimeter. Just got home so it's time to go stick the compression tester on it. Thanks for the link I'll get with it sometime. I can also stop wondering how it orders the two leads

HyperDrachen

Update(I know everyone was hanging on the edge of thier seat). Compression test failure in rear rotor. Though it was so audibly bad I guess i didn't really need the tester. 30psi, though that's my first time ever using a compression tester. Will tear it down when i get a some days off. With regards to the ignition coils I noticed looking down the "barrels" that one side, the side leading to my front rotor, the one that the plug came out clean, is shiny. The other side(stil leading)was dark brown and this ones plug came out brown and white, looked corroded kind of.

The source of my current problem is obviously a bad apex seal, but I'd like to test and service that ignition coil so it's in top shape for the new engine. If anyone has any tips in this regard I'd appreciate it. Thanks for pointing me in the right direction Hailers.

EDIT:ERM wait, something just occured to me. Per Hailer's suggestion i just swapped the leading wires, at the igntion coil. In configuration 1 the car starts, rough idle, only one rotor is powering. Swap the wires, engine won't start. Maybe I've been running off the trailing spark the whole time on the back rotor?