Another Permatune bites the dust

[JK-81SC]

I have an MSD on order, since my Permatune is on it's last leg. I tried to buy a used Bosch CD unit first, but didn't find any for a reasonable price.

My car has been cutting out and not starting after 15-30 minutes of driving. I replaced the green distributor wire a few weeks ago, since that was a cheaper part and it was looking old and brittle. After a few more episodes of not starting, I narrowed it down to the Permatune. I found by thumping the Permatune a few times, the car would restart.

Last night the car died at a light. The people behind we were patient while I smacked the Permatune back to life. That was the last straw, so I pulled the unit out when I got home a few minutes later.

I cut away the aluminum case to see if any parts can be replaced. The entire assembly is potted, and only the backside of a circuit board is visible. I can see one cracked solder joint, which may be the problem. I'll solder it and place it in the trunk for a spare CD unit. So if you have a Permatune and think you are stranded, try waiting a few minutes, then thump the CD unit a few times. Permatune CPR?

Here's a picture of the ugly Permatune guts.

[pope]

Yeah, mine's a paper weight now. After I replaced it with an MSD, the cutting out stopped completely.

[azasadny]

Funny, Permatune claims their units never fail. I had 2 fail on me... now I have a Bosch unit (and a spare).

[RandyF]

I went through several coils and CD Units on my SC until I spotted bare wire on the harness that connects to the green wire. Apparently it had been shorting out whenever it rubbed against the engine. The interesting thing is that the permatune's (2) never really died, they would always worked after I wiggled various wires around and it cooled off I would guess. However two rebuilt Bosch units did burn out along with a couple of coils. In fact I still have a Bosch CD unit for an SC ready to be rebuilt again.

Four different mechanics I hired could never figure this out, but a short conversation with an ex Porsche mechanic who also happens to have been an electrical engineer led to the fix. Actually if I had paid more attention to various threads on this forum I should have figured it out, but all references were to the "Green wire", not the wire from it that connects to the CDI.

[JK-81SC]

Randy,

I'm surprised the Permatune units didn't die as well. That's one case where they were more robust than the Bosch. I'm still looking to pick up a Bosch. If you ever want to unload one of your burned out Bosch units, let me know. I'm going to follow other MSD installations where they kept the factory plug intact. That way I can keep a spare Bosch CD unit on hand if the MSD dies.

[HarryD]

My old permatune used to die also but would immediately come back to life if I placed an ice cube or two on it.

Finally replaced it with a Bosch unit.

Reminded me of the electronic ignition (potted at the base of the distributor) on my old '79 spitfire. Had a similar problem that could be cured by icing the distributor.

[dlagerstrom]

Just finished replacing my permatune (blue case) with a MSD this afternoon.

I had some strange behivior that I could only track to the ignition, so I decided to get rid of the permatune.

I have to say that so far it is much better. I have not opened up the plug gaps yet and I think I need to reset the timing to get it running really well. The car definately runs more smoothly so far, just not perfect yet.

Using some previous threads, I found enough info to be able to just plug in the MSD and it fired right up. Let me know if you run into any snags on your install.

good luck

[T77911S]

if anyone has old bosch units they dont want, i would like them, if you have more than one, i may be able to repair one and send it back as a spare for you.