HAILERS

This factory service bulletin for those that are confused about why one lead plug wire shows a consistent firing and the other does not:
A Distributor-Less Ignition system (DLI) has been adopted in the RX-7 and MX-5 Miata since 1986 production. On a DLI system, discharge from the ignition coil is bipolar - one side is negative, the other positive. Therefore, if a timing light is designed to meet discharge from the negative terminal only, it will not light or will light intermittently at the positive terminal.

This condition is not a result of a vehicle malfunction, it is a problem with the design of the timing light. Please pay close attention to this situation to avoid misdiagnosis.

^ Check your timing light on an RX-7 or MX-5 Miata to see if it lights correctly on each cylinder. The light should work from either the positive or negative side. If it does light correctly, it can be used on a DLI system. If it does not light correctly, do not use it on a DLI system.

^ When purchasing a new timing light, perform the test mentioned above to determine whether or not the timing light can be used on a DLI system.

walterh

So are you saying check the timing with the L1 and L2 and see if they are reading the same? I have a actron timing light.

HAILERS

I'm saying that some people like me experience a problem with L one and L two. On one wire they see a inconsistent blinking. This factory service bulletin put out a decade or more ago explains some of the problem. If you have just a simple timing light bought at Pepboys etc you might just try reversing the clip on the wire. You know, where the clip show an arrow pointing towards the sparkplug. The light works on one wire with a consistent flashing but the other wire shows a inconsistent blinking. Reverse the clip for that wire. That's all I have to say about this. The bulletin above is self explanatory.