We have not come back as we have never left the Porsche scene in the first place. Perma-Tune has remained in production for more than 50 years (
https://permatune.com/about/), exclusively in the USA.
It seems that persons that have problems with Perma-Tune ignitions are those that do not follow factory recommendations, especially those instructions about replacing the ignition coil with the module. Ignition coils do not last forever and are not easily diagnosed without the use of special equipment called a megger. Resistive tests do not detect dielectric insulation break down which is the most common form of ignition coil failure. An ignition coil is nothing more than a specialized transformer.
Generally, transformers have a primary circuit and a secondary circuit. The primary circuit are the two screw terminals that are connected to the ignition module. The secondary circuit is the high Voltage tower that connects to the distributor and then on to the spark plugs. An ignition transformer designed for a car (coil) steps up the Voltage from the primary circuit to the secondary circuit by around 100 times (depending on the coil design). The dielectric strength of the coil, that is what the megger tests, is the ability of the coil to resist the Voltage of the secondary circuit to flash back to the primary.
A defective coil can flash back internally between the primary and secondary circuit windings where the fault cannot be seen or externally between the high Voltage tower and the screw terminals that can be seen. Experience has shown that a coil that has been dented or dropped will likely flash back internally.
When flash back occurs, the Voltage that has been stepped up 100 times will flash back to the primary circuit that has lower resistance than the spark plug circuit. The primary circuit is of course connected to the ignition module. The ignition module cannot withstand 100 times the Voltage it was designed for and fails.
Replace the module without replacing the coil and then the new module is doomed, as is the next one and the next one until the coil is replaced or you switch over to a different ignition module that demands a different coil.
You can see how some people think the module is the problem when in fact the coil is the culprit. This is why we recommend replacing the module and coil together. Perma-Tune is not trying to sell you something you do not need, we are trying to keep you from wasting time and money. We used to say that the original OR the Perma-Tune coil can be used until Bosch started making their coils in Brazil. The Brazilian coils are not compatible with the Perma-Tune module. Professional mechanics are aware of this scenario and so avoid it. DIY mechanics that do not read this information on our installation instructions may experience problems. Fortunately Perma-Tune has a well-staffed warranty depart and offers free testing of ignition components, even those components not made by us.
If you doubt the reliability of the Perma-Tune module, there is a way to independently verify it. Contact a professional mechanic that has an account with a wholesale distribution warehouse. Ask the mechanic to contact his sales person at the warehouse. The sales person can access their data for any given part and see the number of units sold and the number of units returned to the warehouse as defective. You will find that the return rate for Perma-Tune parts are very, very low, especially for an electrical part.
Perma-Tune is the ignition of choice of credentialed, professional mechanics and restoration shops around the world, from US air cooled engine builders like JTE (
John Truman Enterprises Inc.) to legendary race car engine builder Mittelmotor in Germany (
https://www.mittelmotor.de/racing/en/1-9-elektrik/1-91-motorelektrik/1-913-traegerplatte/10329/1-1-91313c-neu-detail).