Perma Tune? Long

[konish]

Well, I posted a while aog about a sudden ignition loss on the highway...whcih rectified itself in about .5 seconds with a LOUD backfire. Since then, no problems. Today (about 90 degrees) I'm driving home and thinking how nice the car is running...I mean really smooth. I had just changed the oil the previous day and all felt right with the car.
Coasting to a stop, the car suddenly died, but I managed to pull off the side of the road. I tried to restart and it it runs for less than a second. Tried again and the engine just spun. Wait. Try again and this time I get a semi-loud clatter from the engine bay, and a small sputter. Almost sounded like pinging...only during the start. Freak. Wait.
I then venture back and look to see if everything is hooked up right, and removed the airbox cover and filter (not sure why I did that). I almost suspected that I had overfilled the oil tank which caused the engine to injest some oil and cause the stall/fouled plugs. Oil level was in the middle of the dipstick. I waited for about 10 minutes, and tried to start it agin...voila fired right up. No weird noises. Oil pressure good. No alt light. Idles smooth and power is fine. I decided to press and got home without further incident.
I wonder: If the perma-tune is indeed dying would it go slow like this or just give up the ghost all at once? I did a search on the board and and can't find and definitive answers, but convention says that CDI can casue some funky things to happen before they die all together. Just for fun, I tried another CDI box the PO had left in the trunk. After unwrapping it, it looked as though it had been in a car fire. When I hooked it up the car ran SUPER rough but pegged the tach as soon as the ignition switch was turned on, and also while it ran...(only let it run for about 2-3 seconds before I chickened out).
One other thing crossed my mind. On a certain piece of highway on the way home, my tach would pulse in concert with the road vibration. What was weird about it was the fact that it happened on the same piece of blacktop road patch, every time. At the time I couldn't figure out why, but if the CDI controls the tach input, then it may give some insight to the internal health of my perma tune i.e. the vibration was resonating through the box causing the weirdo tach oscillations.

thoughts?

r/
Dustin

[Wayne 962]

Perma-tune will test any unit for free to determine if it's okay...

-Wayne

[turbocarrera]

My permatune did exactley that, would cut out when it got too warm, let it cool off for a few minutes and your good to go, till it warmed up again.. never had a tach oscillate with the road though, mine would just randomly blip towards 0rpm once in a while

[VaSteve]

Originally posted by Wayne at Pelican Parts
Perma-tune will test any unit for free to determine if it's okay...

-Wayne

Since mine just crapped out, and I have a brand spanking new MSD from Pelican installed, can you share the instructions on how to have them test it? I'd like a clean bill of health to attach when I put in on ebay.

[Series900]

I would be suspect of the wiring in your car, with age connections start to fail randomly. And just poking around makes the "voila" happen and all is good till the next time.

[power]

Funny I just happen to have an example picture of my Stock Bosch unit that started to fail intermittently that could shed some light. I am not saying this is your problem, only an example of what can happen. I finally started to take apart my Bosch CDI that had failed and has long since been replaced with MSD unit.


What I found is quite common for old circuit boards. In the lower right corner of pic you can see the copper trace of the board has come de-laminated from the board and has actually separated breaking the circuit. This happens over years of heat and vibration. Sometimes it only separates when warm and maintains continuity when cold, thus intermittent problems. Mine showed carbon build up (I cleaned it before I took this pic so I could see the break easier) indicating it was an intermittent problem. I am repairing mine to put it back in service.


P.S. if I replaced my ignition with another unit to see if functioning, I would always reset the timing. Good Luck!

[no substitute]

The Permatune will suddenly shut down because of a semi conductor (large resistor I believe) getting too hot and shutting down. After a fashion it resets itself, although not necessarily at it's original optimum value. Your car will run until the same thing happens again. Eventually it gives up the ghost permanently.

[Lorenfb]

You really can't test the Permatune for intermittent conditions because most
problems are thermally related, i.e. the CD unit fails at a certain temp. This
is a common problem on the Permatunes because of the thermal expansion
problem with the electronic components/circuit board which results from the
potting compound being used.

Most Permatunes are very unreliable and one should avoid using them if you
want to return home from a drive in your Porsche. Many resellers refuse to
warranty the units and "force" the buyer to deal directly with Permatune.

[targa911S]

I have posted on this subject many times before. I paid good money for a Permatune when I accidently fried my Bosch CD. It did the same thing you are experiencing with regularity. Plus, if you let the car idle anywhere near the garage, out of nowhere the garage door would just start going up and down by itself! It would actuate my garage door opener! I sent the Permajunk back for "testing" to them and of course it was fine according to them. So I stuck with it. Still not having the problem solved, and determined to resolve it, I bought a used Bosch box from my local tuner and hooked it up "piggy back " with the Permafail, then set out on the road. When the engine cut out and shut down, I got out of the car and quickly swapped the plug from the Permacrap to the Bosch...as you say ...viola! I could drive all day! I did this about a dozen times, called Permascrew and told them the results. They then told me it was my wiring and refused to refund my money. I now use it as a paperweight as a reminder of what bandits those guys are. If you need a Bosch CD, PM me as i have collected a few as back up so I never have to deal with the Permajerks again.

[konish]

Targa,
Thanks, and yes, I'll send you a PM. I have heard of the heat related issues with Permatune boxes. However, like in my case yesterday, I only waited about 10 minutes and it started right up and ran for as long or longer than the leg of my trip when it failed. I would think that once heated it would have shorter interval between failure becasue of the residual heat left in the housing/engine bay? Not sure, which is why I am asking. Also, I would think that when it does fail, it would act as though the ignition was turned off. Mine kinda petered out...more like it ran out of gas. During my attempts at restart, it would try and start but only for a split second and die again...actually some attempts just spun the motor. I'm sure there must be many failure modes, and symptoms can vary. Truth be told I'm not sure what the heck happened because I couldn't diagnose my problem properly and logically. My ideas are this...
1. Bring a sparkplug along so I can diagnose whether or not the spark plugs are firing. If not I'll have a good spare CDI to swap in when/if it does it again.
2. Ensure its not fuel related (recent, new fuel pump), and maybe bring a fuel pump relay with me as insurance.
At any rate I think a CDI backup is cheap insurance but it sure is hard to do a good diagnosis on the side of the road.

R/
Dustin

[dhaines]

This post in eye opening. I gave up on mine a while back because it would just quit. Sounds like the hot engine compartment of a 911 is not a good match.

[Jamie79SC]

When I bought my '79 SC, the PO had installed a Permatune because he said that that it solved a miss at high RPM and load.

Shortly after I bought the car I replaced the very aged plug wires.

A year or so later the car would, on occasion, refuse to start. Crank, Crank, Crank, wait, wiggle the CD, hold your jaw just so, cross your fingers, START. On a whim, I replaced the Permatune with the old "defective" Bosch CD that the PO had left in the trunk. Car has run flawlessly since. My suspicion is that the new Permatune initially masked the sub-par plug wires, making the Bosch look bad. Bosch is actually GOOD. The Permatune gave 2.5 years of service before failing. The now 25 year old Bosch is going strong.

Bosch CD = Good CD. Permatune CD = Bad CD.

[mskala]

I also had 2 permatunes that would do the same thing, fail
when hot, waiting made them good again. Although in my
case it would always happen when car was shut off, like to
get gas. Not during running.

Anyway, found a good Bosch unit, and I just keep the permatunes
for backup.

Mark S.
'70 914-6

[Wayne 962]

Originally posted by Lorenfb
Many resellers refuse to
warranty the units and "force" the buyer to deal directly with Permatune.

This is standard procedure for just about everything. You can't take your SONY CD player back to Circuit City eight months after you bought it asking them to fix it for you. No, you send it back to SONY...

-Wayne

[Mysterytrain]

Thought I would offer my experience...My 78SC started to do the exact thing you talk about. My car would cut out..I could turn the ignition switch off, then back on and it would restart and I would go on my merry way..I was baffled by it and also scared as hell that it would happen when I was in a turn and my ass was hanging out. Anyway, I finally took my car in for service to have this looked at..this is after a year or so of intermittent cut out. The mechanic replaces my ignition switch...2 weeks later..the car dies again. To make a long story short one day the car dies and it won't restart...I call to have it flat bedded home..as he is pulling the car onto the bed massive amounts of oil spills to the ground...not a good sign [as in $$$$]. Seems my distributor seized, sheared of the drive gear and dropped it down into the case where it got caught on some moving parts and launched out the side of the case. The car is in for a total engine rebuild as we speak. Now, I'm not saying that your problem is the same as mine but you might want to ck the distributor shaft for play and of course I'm going to be looking at my CD box..I might have been suffering from two problems. PS. I'm looking for a 3 liter case if my can't be welded and a 78 distributor. Peace, Ron
www.mysterytrain.org