No spark on number 1 rotor?
 

So my car is running on just the rear rotor despite the fact that it has fuel and a reasonable amount of compression. I get spark when I pull the wires and hold the plug against the engine.

But I took a slow-mo video of the video and it seems like I'm only getting one leading spark every two compressions (based on the sound of the engine).

Shouldn't the leading coil be firing twice as often as the trailing coils since it has a wasted spark?

I suspect I may not be getting any trailing spark on the #1 rotor but its kind of hard to test since the plug cord is so short.

I am getting trailing spark and it seems to happen at about the same pace as the leading spark, which probably shouldn't be happening.

Does *anyone* have an idea why I'm only getting half as many sparks as I should?

The engine is running on a PowerFC.

Are you getting leading spark on your rear rotor?
Test your coil packs and wiring leading to the coils.

Yeah, I'm getting leading spark on both rotors but only half as many sparks per revolution as I should be, if my interpretation of the video I took is correct.

Which would explain why only one of the rotors is firing.

If you getting spark on both rotors then both should fire, have you checking your settings on your PFC?

I don't have a PFC commander but will try to borrow one.

Since the RX-7 uses a wasted spark on the leading plugs it should be firing twice as often as the trailing plugs, no? (six times per rotor rotation, or twice per shaft revolution).

I think the previous owner had the coils in the wrong place... or modified their location for some unknown purpose. The leading coil was in the middle when it should have been on the right (the coil rack and wiring is not the same as USDM FDs).

Are you running stock coils or aftermarket?

Stock, the coils are. The blue connector for the T2 coil was plugged into the leading coil. But the white T1 connector seems to be getting the leading signal.

Thats not good, I wouldn't try start the car until you sort that out, check the pin out on the ecu and make sure the right wiring is going to the right coil.

This link helped me out big time when I was trouble shooting my ignition.

https://www.rx7club.com/3rd-generati...iagram-964089/

Thanks. I wonder how that compares to the JDM Rev. 4...

Just check the wire colours and see if they are the same, I have a JDM and the wire colours were the same.

I just realized that besides the L and T2 coils being in the wrong place, the plugs were also backwards. That explains everything.

Except the engine still won't rev (past about 3,500 with no load) and constantly floods and won't start again until I blowtorch the plugs.

What the hell.

I've got spark on L1 and L2, at least...

L2 gets fouled with black stuff after about five minutes of idling and the engine stops.

I'm still not sure that #1 is actual firing even though it's got fuel and spark.

Have you checked your injectors, maybe they are leaking and causing the flooding, what mods have you done to the car?
Could be a number of things, bad spark plugs, bad spark plug wires, injector sticking open due to build up, injector O rings damaged.

One of them has a tiny, tiny leak but its so slow I don't think it could possibly cause flooding. They're not stuck open... and they do fire.

Spark plugs are mostly new but have been fouled a few times and I have new ones on the way.


I actually changed the injectors to some supposedly good ones I borrowed (for test purposes).

The plug wires are also borrowed and they're out of spec but not broken (have new ones on the way).

I haven't done any mods... not really. But it has a single turbo. It hasn't run right since I got it running.

What could the o-rings do?

Well I think you need to fix your leaking injector, are the injectors standard or aftermarket with aftermarket fuel rails?

I would wait for all the right items to arrive and start again, it sounds like everything you have is not to spec and could be causing all your issues.

Stock.

I wonder if all the black smoke and the carbon on my L2 plug is simply that its only running on one rotor, which happens to be pig rich?

I would get all your injectors cleaned and checked, get new o rings and injector hats while you wait for the plugs and wires to arrive, then you know everything is good to go and if you still getting flooding on the rear rotor, I would do a compression test to see what the compression is like.

Plugs and wires will probably be here today or tomorrow. Injector cleaning will probably take at least a week but I will do it once I'm convinced the engine isn't just toast.

I tried to use my piston comp tester but the damn hose wouldn't go into the plug holes... hehe. I would guess the compression is low but not blown.