How do you test which coil is Leading? 1985 GSL-SE
 

I have done the legwork trying for an absolute answer and keep reading contradictions. Most say the Leading coil is the one closest to the headlights. Some say the opposite.

I also read that the coil wires to the distributor cap should not be crossed. That is OK as long as you know the cap is on correctly and which coil is the leading.

I am the third owner of this RX so I don't really know if it's ever been worked on in this area. So, my question is simple but complex.

1) I believe the car will start on the leading coil only but not on the training coil. I can disconnect one coil and she starts, reconnect and disconnect the other and no start. Can someone confirm?
2) The front coil has a Yellow / Green stripe wire. The rear coil has a Yellow / Blue stripe wire. This matches information I was able to dig up on the net. This makes the front the Leading coil. Please confirm.
3) The particular cap on the car right now has a very distinctive notch. When installed so the notch drops in place the cap is as shown in the photo. Note the wires cross! The cap can be installed 180 out and the wires do not cross. Also, installed 180 out from this photo it looks like other photos I find of the cap.

Sorry, long post. I want to be able to say which coil is ELECTRICALLY the leading and then wire to the distributor cap. I believe making sure the color coded wires are a certain way and knowing the starting on one coil answer will give me the info I need. Since I have not owned this car all it's life simply saying leading is the front (or rear as some say) is not enough. I want to test this.

Finally, the car runs smoother in this particular description the front coil goes to the leading. What I question is if this is correct. Possibly the rough idle with reversed is another problem I need to find. See my dilemma?? Thanks in advance for any help.

First Photo - Front Coil.
Second Photo - Rear Coil.
Third Photo - Cap on most natural fit to notches.
Forth Photo - Wires Crossed.

Coil near the headlight is trailing. Other is leading. The trailing should have yellow wire w/ green stripe on the (-) terminal. You will also see a blue spade connector that should be on the trailing (-). The leading coil has a yellow wire w/ a blue stripe on the (-) terminal.

The coil wire to the dizzy should not cross. The trailing coil (to the front of the car) runs along to the "T" post on the cap (upper left corner). The leading coil (furthest from headlight) goes to the center of the cap ("L").

Once you check that, the next thing is to check the ignitors (boxes on distributor). The one closest to the rad is leading. Should be a white plug and the yellow wire should have a blue stripe. The box closest to the alt is trailing and should have a blue connector and the yellow wire should have a green stripe.

Then check plug wire. Front rotor is 1, rear is 2. Leading plugs on the bottom, trailing on top.

Good luck.

Kent

just look at the markings on the cap.

https://www.rx7club.com/attachment.p...7&d=1332501611

Michael,

He is saying that he doesn't know which coil is which and whether someone messed with the connections to the coils (on the + and - posts). Based on what I see, his front coil is still trailing and the rear is leading (like it should be). He needs to fix the coil wires (shouldn't cross) and will need to check the ignitor connectors in case someone messed with them.

Once all of this is done, he should throw a timing light on it and set/check the timing.

Kent

Made the changes
 

OK, made the changes. Started up and the idle is rough. But, that could be a different problem. Also I need to put a timing light on it.

If I disconnect both coils and connect the Front coil to the L on the distributor cap the car will start. It will not start if I connect the Rear coil to the L. That confuses me. I expect and read somewhere that rotaries will run on the leading only but not on the training only.

Hate to ask this, but could someone try this and tell me if you can start your car with the front coil connected to the L on the distributor, and nothing on the T?

Never mind.
 

Never mind about checking this. Thanks to those who helped figure out the coils for me. They were reversed. Let me work on the timing and ignitor wiring confirmation.

Ignitor wiring confirmation.
 

Removed the cap and rotor. Found Leading ignitor and disconnected the connector. Disconnected the wire running to the rear coil and confirmed the rear coil is wired to the Leading ignitor.

There was resistance to the front coil but that makes sense as it's reading through the other wiring. Only the rear wire is a direct short to the Leading ignitor connector.

Thanks, that confirms the wiring. As to why it will start on the front only, at this point not worth investigating any further.

Next is timing.

The idle is a little rough now and was not rough with the coils switched. Unless that's a clue to someone there are many rough idle threads for me to read. Again, thanks everyone!

Bad leading ignitor?? Getting close!!
 

Bought a $39.00 timing light at Auto Zone. Read instructions and connected to the leading L1 wire. This is an inductive timing light. NOTHING! No timing light.

Connected to T1 and got a nice strong timing signal. T1 timing at idle is 1/2 way between yellow and red timing marks.

Physically swapped the coils, still no light on L1 or L2. Still good light on T1.

Removed the wire to L1 and connected to a spark plug and laid it on the shock tower. Cranked the car over, nothing. To be sure I removed T1 and connected to a spark plug laying on the shock tower and nice spark.

Already checked connections and made sure the wire from the coil to the ignitor is good. Do I have a bad Leading Ignitor and where do I buy one? Auto Zone??

Your best bet is to get a good used one on here. Check the classifieds or post a WTB thread in the classifieds. They are expensive new >$240 last time I checked, but you can usually find them used for about $25. I would get at least two used ones since one might be bad or you may need to have a spare for the future.

Looks like you are on the right track.

Kent

Fixed!
 

I did find one locally for $30.00 and installed yesterday. Now I have fire to Leading and Trailing and was able to set timing. I consider this fixed and really thank all that helped! Special thanks to GSL-SE Addict! I have other questions but will start a new thread. :)

Glad to hear that you got it fixed. :)