I swapped out the spark plug wires on my 91 RX7 and low and behold, the leading spark plug wires were mixed up. Rotor 1 leading was connected to rotor 2 spark plug wire and terminal on the coil pack, Rotor 2 leading was connected to rotor 1 spark plug wire and terminal on the coil pack.

What damage could have occured? I drove it about 50 miles like that a couple trips to redline and the engine ran flawlessly. The only difference now is the engine doesn't smoke on cold startup anymore, I mean, not even a puff of smoke. Before I fixed the wiring, it smoked REALLY bad on a cold start up, like "people pulling over because they can't see" bad. Now it is mint. Is this possible or is it a coincidence?

 

With the leading wires mixed up, I believe they would have been firing in the exhaust stroke. If I'm right, that would mean the leading spark wouldn't have been causing any pre-ignition, since it wouldn't have been during a compression or intake stroke. You were running only on the trailing plugs before, so I wouldn't be surprised if your power and mileage improve greatly now. I'm also not surprised that running on the trailings alone caused a lot of unburnt fuel to make smoke.

 

Swapping the leading ignition wires around will make no difference. They both fire at the same time anyway. Swapping the trailing wires around will cause problems though, so don't do that.

[disclaimer] I am not very familiar with the specifics of 2nd gen ignition systems, other than how they are used to modify the systems on 1st gens. But I don't believe the firing of the leading changed between the two generations...


.

 

How could they fire at the same time? When rotor 1 is in the compression stroke, rotor 2 is finishing the intake stroke on one face, and beginning the exhaust stroke on another. This should mean that when the tip of rotor 2 is approximately centered between the lead and trailing plugs, the leading plug on 2 fires due to the CAS signal (or distributor) for rotor 1. The leading plug would likely be on the exhaust side of the tip (the face that is in the exhaust stroke), but it would vary with timing advance/retard. Right? The lobes on the e-shaft are opposed, so the rotors are opposite in orientation to one another.

 

Since there is only one ignitor in the leading coil pack, it fires both plugs at the same time. This is called a "wasted spark" ignition system, due to the fact that the plugs fire once on their duty cycle and then again during exhaust (which is a wasted spark). The wasted spark has no effect on the performance of the motor, emissions, or anything else.

 

I knew there was something missing. I totally forgot about the wasted spark due to there being only one lead ignitor. At least my previous description still works in discussing trailing spark. As you mentioned, swapping those wires would cause pre-ignition and destroy apex seals.

 

can someone post the correct plug wire setup is the rotor closest to the rad T1 and L1

 

the top is trailing and bottom is leading right

 

The housing has T & L cast into it, and the coils say L1, L2, T1 & T2 right on them. Just follow the wire to the plug.

 

1 is closest to the radiator, 2 is closest to the firewall.

 

mine have been mixed for a while.now the car wont start what can i do to help it run.