I never had a problem with my original distributor that came with the car. It lasted for 22 years, and likely would have kept going. But when I was putting all kinds of replacement parts in at the 200,000 mile mark, I decided to get a new distributor also. I guess a lot of drivers are interested in the HEI mod for reliability, but I never experienced that problem.
Now the new distributor with the replacement engine is working well. It has the same firing order as the original KL engine, and the distributor is also a fit for the original 1994 KL engine. That was a complete surprise, because the distributor cap that came with the replacement engine has a completely different firing order marked into the distributor cap ! Starting from left bottom, it goes 5 4 6 3 2 1 around the circle, whereas the distributor cap order for the new distributor, and in the books, is 4 5 3 2 1 6 !!! How can that be ?
I only have a basic understanding of how the ecm and distributor work together to stop the engine when there is a diagnostic problem, or input failure. The secondary cable harness on the distributor has 8 or 9 wires bundled. If one of these, such as the knock sensor, does not send a signal to the distributor, will that shut down the engine, or keep it from starting ? How does that circuit go - the distributor checks for a knock sensor signal, via the ecm, and if not there, will not start ?
The ECU only needs the crank signal for the injection pulse to happen. Prior to 95, the ECU needed cam(dist signal G), cylinder ID(also dist) and crank signals to send the trigger signal to the Ignition control module located into the distributor to have the coil fired. After 95, Mazda got rid of cylinder ID in distributors.
There are many types of distributors on the K series that are not all interchangeable. They also have different components that might or might not fit each other and make your life miserable while you're trying to make sense of it. Also, some JDM KF/KLZE's even came with 7 nipple distributor caps because they had external coils (OEM HEI mod!).
There is no such thing as the ECU stopping signals from happening. It's the other way around actually. The ecu needs signals (see 1st paragraph) before it sends ignition trigger and injector pulse. The ECU also needs to be properly powered.
The knock sensor isn't necessary for engine operation. You can leave it unplugged and run the car. It only sends signal to the ECU when the engine is knocking.
The distributor has between 7 and 9 wires, divided in 2 plugs. There should be a 6 pin plug and a 3 pin plug (even if you don't have that amount of wires. The smaller plug has 3 pins and between 1 to 3 wires depending on model and year. The biggest wire is the 12V, the other 2 are tach signal and diag box pin ign-. Mazda have deleted the last 2 during production. The other plug has between 5 and 6 wires. There should be a switched 12V, 2 or 3 wires to the ECU(G signal, Ign trigger and pre-95, cyl ID) and 2 grounds. The order of the wires on the connectors change throughout the years and should be looked up with your individual model and year.
My theory about distributor failure is that oil leakage from valve covers covers the distributor, seeping in then causing failure of the ICM/coil.. It is mainly due to poor maintenance. Probably add-in overstraining the coil with defective wires and plugs. If you kept yours in good shape and not covered in oil like most KL's I've seen, I'm convinced they could go on for a while.