Ignition problem

Targa77 · Targa77's Garage

I've had this problem with my car since I purchased it last August. I thought that I had it cured with a new rotor, points, cap, etc. The car will run great for a few miles and then it will just cut out. This has happened at least 5 times. Last Saturday, I left that morning to run an errand. The trip was about 10 miles. When I came back outside, my car wouldn't crank. It would turn over, but it wouldn't start. I had it towed to my house and proceeded to check the ignition. The point gap was correct (.014 according to my owners manual), all connections were clean (I cleaned all connections earlier). I'm getting 12 volts to the fuse block and the Permatune unit with the key switch on. I'm also getting 12 volts to the terminal on the side of the distributor. I took the HT lead (terminal 4) off of the coil and held it to ground-no spark at all. I'm supposed to be getting 12 volts to terminal 15 on the coil with the ignition switch on but I'm not. I have checked all wires with an ohmmeter and I'm getting good continuity. My Permatune unit does make the usual whining noise. All grounds look good. I checked my coil per the Haynes manual and it is out of range. Supposed to show 4-6 ohms between terminals 1 and 15 and around 900 ohms between terminals 1 and 4. I'm showing 7 ohms and over 1400. My Haynes manual states that if you do not get at least 9 volts to term 15 with the key on, then the switch is faulty and/or wiring. Please help guys. I miss driving her.

Superman · 02-12-2002, 05:54 AM

TEchnically, your coils is out of spec, but I suspect it would work just the way it is. If it is not getting voltage where it should, then this would be why your car does not run. I'm not sure where the wire to terminal 15 is coming from, but I'd trace that wire back to where the problem is. Based on your comments, it sounds like it might be coming from your ignition switch. If so, don't be surprized. Ignitiosn switches fail. This is a round plastic switch thing with MANY wires attached, that is attached to the back of your ignition tumber (where you put the key). Be sure to NOT hang a heavy bunch of keys from this tumbler. If you do, you'll wind up buying a very expensive new tumbler. No kidding!

Targa77 · Targa77's Garage

Thanks, I'll try just replacing the electrical part of the switch first. Hope that takes care of the problem.

john walker's workshop · 02-12-2002, 07:41 AM

the haines manual must be wacko. the only 12V you should see is in the red wire to the permatune. if there was 12V to the points, they would fry. permatunes don't whine, bosch units do.

Targa77 · Targa77's Garage

Thanks, now I'm really worried. I did check the red wire that goes to the Permatune and it does get 12v with the ignition on. So, if it's not the ignition switch, could the Permatune be faulty? Is there a way to test it?

john walker's workshop · 02-12-2002, 08:20 AM

www.permatune.com click technical support, click porsche, click 911, and you get the checkout procedure and lots of other info.

Targa77 · Targa77's Garage

Just did. I'm going to perform these checks and let you know what happens. Thanks...

Argeo · 02-12-2002, 10:15 AM

I am having the same exact problem with my 77 Carrera (WOR). I also have Permatune. I've just sent my Permatune to the company to have it checked. But other than that, everything else seems fine. Did your car do anything strange before it died. My car let out a huge backfire and just died. Please let me know what you find out.

Thanks.

Targa77 · Targa77's Garage

Here is what I have found out. I did a bench test of the Permatune according to the very detailed instructions on their website ( Thanks John Walker's Workshop). My Permatune has been fried by my coil. I will be replacing both very soon. If you need detailed instructions, go to http://www.permatune.com/Technical%20Support/Porsche/911.htm. I hope this helps.

Targa77 · Targa77's Garage

I forgot to answer the last part of your question. Nope, my car did nothing but just cut off-no sputtering, no backfires. Ran like a champ that morning and then it wouldn't start up. New points gapped to .014 according to my Owner's Manual, cap, rotor, checked all grounds, checked all 12V feeds, just no spark. My coil had black residue all along the top and it didn't pass the shake test. My Permatune made a whining noise even though it's not supposed to (once again thanks to JWW for this info).

Craig · 02-13-2002, 11:07 AM

This all sounds suspiciously like my problem also (thread Detectives: Unusual Problem). As soon as I can get some 'testing time' I will try the tests outlined in the document.

Craig
77 911S