I have ignition, no I don't, I have ignition, no I don't?
 

I bought a stock 72 911T Targa last August and have been working to bring it back to life and looks.

After getting it running in September and driving a couple hundred miles, it suddenly started missing severely and I limped home with it. After that I did as much trouble shooting as possible, cleaned ground wires, fuses, fuse block connections, and then it would not fire at all. I replaced the Bosch MSD unit(even though it whistled) and coil with a Permatune box and new Bosch coil... It started and ran good. I put about three thousand miles on with no problems.
(I had already replaced the spark plug wires, points, dist cap and plugs)

A few weeks ago I decided to see if the original Bosch unit would work, hooked it up and it ran even better!
I drove around a couple of days with a grin on my face and took it to my first car show. It started right up after the show was over, ran for about 45 seconds and died. No hint of spark. I had put the Permatune unit in the glove box and had some tools along, so I swapped it out.. it ran fine again.

So a couple more hundred happy miles go by, I'm sitting behind a school bus idling and yep, it dies again and refuses to start... aaarrrrgggg!

As luck would have it gravity and a short tow got me home. I start trouble shooting again using the Haynes manual... no obvious problems, but it won't start. I change back to the old Bosch unit, no fire, change back to the old coil too... it runs again!!!

I don't trust it now and am not sure what else could be causing all this fun.

Any suggestions?

Skip,

What is the Bosch part number on the 'new' Bosch coil?

Have you cleaned both sets of 14-pin connectors in the engine compartment? And the ground lug and Faston connectors as for the CDI ,too? Vinegar, pipe cleaners, wire toothbrush ... let set for 5 minutes, then rinse with distilled water and final spray-off with 90% isopropyl alcohol is my preferred cleaning method for the Faston connectors. Oxidation on Faston connectors can be invisible, and hard to track down as a problem spot!

It was the same part# as the stock one, I'll post it when I get home...
I did clean the 14 pin connectors and grounds, but used very fine sand paper.

Something else that was odd? Right after it died on me the last time, I pulled off the cover to check fuses in the engine compartment and I noticed the voltage regulator was very hot, too hot to keep a finger on for more than an instant... do they normally get that hot?
It was after about a half hour of 60-75 MPH and then some idling an 30-40 MPH driving.

front fusebox loose/corroded connections maybe. my old 69 kept doing that right after i bought it. i found a crack in a joining strip on the back of the fuse box/panel. heat expanded things and affected the connection off and on.

Thanks John, I'll go through the connections again and clean them up, your suggestions are always great!!

Early S Man, the part # on the coil is 0221121001. should I have used a different coil with the Permatune?

I'm still wondering about the voltage regulator too... do they get pretty hot under normal use?

I don't know if the regulator would get that hot if it was full fielding the alternator.. did you ever get a chance to check system voltage?..............Ron

Put a new set of points on the car.
Also, keep the Permatune somewhere else,
but not near the car.

Good luck
Loren
Systemsc.com

I hope you checked the points setting since the install 3k ago

At a recent R Gruppe picnic, a guy there described symptoms when his CD box went. It always whined, but he would experience the car stuttering, like running out of gas, then the car would run fine, then stuttering again...finally, the unit died completely. Sound familiar? I believe all of the above posts give good advice...

Skip,

That is the correct Bosch coil ... I was worried that a Permatune person might have told you to get a Bosch 'Blue' coil, and they don't work well with the factory CDI-system!

It is very important to isolate the problem to either a supply Voltage problem, or CDI-unit problem! One way is to build a test lead from a 12 Volt accessory plug to dual banana plugs ... so you or an assistant can monitor the system Voltage at the instant missing occurs. An analog multimeter actually works better than a DMM, unless the readings can be logged to a laptop PC for review. What you would be looking for is a significant drop or rise in Voltage associated with a missing onset event.

The following set of theads may give some insight to past CDI problems on the board, and the troubleshooting done to resolve the problem:

http://forums.pelicanparts.com/search.php?s=&action=showresults&searchid=303752&s ortby=lastpost&sortorder=descending

More great suggestions, looks like I won't be bored this weekend...

Loren,
I visited your web site and I'm impressed! I might have to get in touch with you about checking out my original Bosch CD unit, the Permatune stuff seems to get lots of bad press! it cracked me up when I read "keep the Permatune somewhere else, but not near the car."

I'd love to get to the bottom of my intermittent ignition condition.

Please feel free to call anytime. My phone number is posted on the website.

Some of my Posche shops have had trouble with some of the Bosch
coils, mainly the silver ones. These coils cause intermittent problems.

Good luck
Loren
Systemsc.com

The new Bosch coil I have is silver... hmmm, it tests right in the middle of the values given in the Haynes manual, .05 ohm between the #1 and #15 (Primary, Haynes says .04-.06) and 675 ohms between #1 and #4 (Haynes says 650-790).
The readings are with the coil cold and out of the car... I may try it after running a while (assuming it will). I'll test the old coil too and see what the values are.
I love electrical problems.
http://www.pelicanparts.com/support/smileys/pyth.gif

The clue you guys overlooked is the hot Voltage regulator. So now you are doing the box swap two step. The ignition boxes ( both of them! ) are telling you that they are getting too hot too and are shutting down to cool off. Ever wonder why?

Skip, if you are a DIY type, you can believe what a guy on the internet says or you can educate yourself. Buy and read the real shop manual first, that is your license to learn more. Then use Google and you will find a vast collection of additional raw technical information on the beloved 911.

Below is a link to a source of information, in addition to the shop manual, for your car. This information has been collected and collaborated by professional mechanics from all over the world during the course of 30 years.

Free.

I recommend you focus on the GROUND CIRCUIT and CHARGING CIRCUIT sections of the DIAGNOSTIC GUIDE.



http://www.perma-tune.com/Technical%20Support/Ignition%20Modules/porsche/911.htm

Regards,


Lonnie


P. S. About the issue with the coils, here is a copy of a post I made a few months ago.



I saw your Rennlist E mail and wanted to respond to it to clear up the confusion and to say thanks for the complement.

To answer your question in a nutshell, it is pure economics, not nostalgia for the 60's, that the blue coil was recommended by me as a replacement unit in the context of a repair part for the 911.

As you know, when the ignition coil shorts internally, the high voltage pulse that should go to the spark plug feeds back to the ignition box. All it takes is a few sparks from the thousands of sparks per second that the coil generates to cross the dielectric barrier between the coil primary and secondary circuits to nail the box. To prevent the replacement ignition box from suffering the same fate, we recommended replacement of the ignition box and ignition coil at the same time. Our recommendation of the stock black coil was criticized as being too costly (the special black transformer coil you spoke of in your e mail).

In racing circles, it had been proven that the Perma-Tune system can operate at 40KV and not exceed the dielectric strength of the weakest link in the high voltage circuit, the distributor. Since the blue coil was readily available and inexpensive at the time, and its turns ratio would not put the operating Voltage above 40 KV, we recommended its as a substitution for the stock black coil under certain conditions. The conditions were that the blue coil could not be used with the stock ignition box, only the high performance ignition. We also recommended that the spark plug wires, distributor cap, rotor and spark plug resistors be checked after installing a blue coil due to the tendency of these components to reveal defects under higher operating Voltages.

The rush was on after people found out how much better the 911 ran, and on cheap fuel, with the high performance ignition, coil and a good set of wires combined with a big spark plug gap. When the supply of blue coils ran out, we recommended the new Perma-Tune coil. Many other coils that were supposed to be a blue coil equivalent have been tried with very little success. When the blue coil supply came back, it was not made in the same place and is defiantly not the same quality as the old blue coil. Our coils are similar to the blue coil in electrical terms but are designed to look like the stock replacement coil (black with a brown top) and are specifically designed for use with any Perma-Tune ignition. You can not get away with using our coil with stock ignitions, we do not recommend even trying it.


911 info

Thanks Lonnie for the suggestions and guidance, I have the Haynes manual, and several other publications but not the official Porsche manual or the Bentley yet... they are on my list of must haves.

I do use this board and the collective knowledge of people that not only have the official manuals, but also an amazing level of real world experiance.
I trust the recomendations and suggestions from many on the board, John Walker, Early S man, Ronin LB, PWD72S, and Bobby to name a very few. They have helped me and many others zero in on problems not covered by any manual, for this I'm grateful. There is nothing like having a vast array of experts who like to help others that share a passion for Porsche's!!

I did go through the ground and charging circuits, pulled the electrical panel from the engine compartment, cleaned and resoldered the bare wire to fuse connections, cleaned all the faston connections using Eary S man's method, cleaned all the ground connections and check resistance...
I used the Permatune document and bench tested the unit, it checked out good, as do both coils I have.

I reinstalled every thing and kept the Bosch CD box and old coil installed. It started right up and ran perfectly for 40 seconds, died, and would not re-start. I noticed that the Bosch CD was not whining (only me at that point). I checked the power feed to the box and had 13.5 volts...
I quickly put the Permatune back in, the car fired once and then just cranked. As I was cranking I put some sideways and up an down pressure on the key, it suddenly started and ran fine for 30 minutes. it would also then re-start. Hmmm, maybe the ignition switch!!! seems odd that it would only quit at an idle periodically.

I'm going to see how much I can get into and clean contacts in the ignition switch, and also go back through the front fuse blocks like JW suggested.

One more question, I noticed a post about voltage values read while running. I checked mine just to see what it was doing, key on (not running) i get 13.5 volts. Running at any speed I get 14.5 volts and it stays rock steady reving, at idle, ant held at 3500 rpm... should there be a variance at different RPM's??

Oh, one more thing! The voltage regulator was only warm to the touch after 30 minutes of spirited testing...

Skip,

It sounds like you may have had two problems going on at the same time ... and you fixed one of them by cleaning all of the grounding and connections!

You can replace the electrical portion of your ignition switch at reasonable cost ...

It sounds like your Voltmeter is reading about 0.5 Volts high, as fully-charged batteries typically are 12.9 - 13.0 Volts, unloaded --open circuit without a significant load. Your fuel pump and ignition aren't much of a load. Factoring in a 'hig-reading' meter ... 14.0 Volts sounds like a very well-performing alternator and regulator. At high temps ... above 190° F oil temp ... the Voltage may drop by perhaps 0.5 Volts, and that would be perfectly normal.

You are welcome Skip and nice to see you are making some progress. It seems you are peeling an onion here with your electrical system. Yes, it is nice that you can get a little guidance on the board. Wayne is to thank for that. He puts much work into keeping this BBS going.

Lonnie,

I just wanted to "chime in" and thank you again for the assistance you gave me last July with an old PermaTune CD box I sent to you for testing. You determined that water had gotten into the box and "shorted it out" and you didn't charge me the $20 bench test fee. I put a new CD unit and blue Bosch coil in, as well as put in a new wiring harness that your company made and my ignition problems are over. I really appreciate your patience and well-documented website. You also walked me through the troubleshooting/testing process and that really helped. Thanks again!!!

Yep... me to

which makes it difficult to be mechanically objective on this thread.. your group was dialed in on educating me.. and I respect that... thanks .....................Ron