Intermittant spark, Could this be my pertronix? Options

[zehrschnell914]

After all of the problems (all electrical) I've had with this car, it died on me again. Turned over and all other electrical worked (including fuel pump), but wouldn't start. Guessed no spark and had it towed home.

Next day I pulled the coil wire to check it and it had great spark. I turned the key and it fired right up. I let it run for 10 minutes then backed it out of the garage and it died again. Pulled the coil wire off and had the lovely wife (IMG:style_emoticons/default/wub.gif) crank it over again and got nothing! All of the ignition components are new and I have installed a Pertronix kit. I looked for the points that came with the dizzy, but couldn't find them. Any ideas?

Mike

[McMark]

Could be a coil as well. Maybe the tranny ground strap? Is the pertronix still adjusted correctly with the correct air gap and the sensor ring is pushed all the way down? Did you take the distributor out recently and not get it back in all the way?

That should keep you busy. (IMG:style_emoticons/default/biggrin.gif)

[zehrschnell914]

Thanks Mark. I did replace the tranny ground strap, but I'll check it along with your other suggestions.

Mike

[Joe Bob]

Put the old points back in...if it fires up it's that piece of shit Petronix....ooopsie, DID I say THAT?

[KitCarlson]

Check the ground braid in the distributor.

Use an ohm meter and check for near zero ohms between the plate where the Pertonix is mounted and an engine ground. When the ignition is dead.

The braid grounds the points or pertronix to the case. Without a good ground the ignition might be intermittent. The plate moves on a ball bearing with vac advance, no a good connection without a braid. The Pertonix can also be damaged with loss of ground. I found this when testing the ignition in a drill press, lost a ground, the Pertronics poofed. I can explain why, but that is a long story.

If the braid is broken or missing it can be replaced by soldering in some fine copper solder wick.

The addition of a distributor ground wire from the case to a nearby engine tin screw grounds the distributor when timing is adjusted. The distributor seal can isolate the distributor when the distributor clamp is loose. The ground has to go up the shaft and through the bearings, not very good. The ignition requires several amps to charge the coil, and it needs to do it quickly.

Also check the gap at the Pertronix to magnet, use a plastic 0.01" feeler.

Sometimes the rotor bottom must be shortened to allow for the space consumed by the magnet assembly. If not the rotor over extends and damages the carbon button in the distributor cap. I have also found that the rotor base can bump the top of the Pertronix and spread the gap. Look for wear signs on both parts. It is sometimes elusive, since the plate movement changes spacing.

Kit

[need4speed]

Gremlins.

It's gotta be those damn Gremlins.

Kit;
would you recommend a separate external ground wire from an external screw on the dizzy (maybe one holding the vacuum can in) to a bolt on the case - perhaps to clarify the ground signal some? I have habitually left my dizzy clamp slightly loose in order to facilitate the constant tweaking and adjusting, but I've also always suspected that some of my problems are from intermittent spark - due to either condensation or dirt or just plain bad luck, or possibly crappy condensers - so if it's been a grounding problem all along for me, do you think the addition of such a wire would clear it up?

[zehrschnell914]

Thanks Kit, I'll check that too. Need4speed, you are funny!

Mike

[J P Stein]

Failure mode for a coil is just like this.
Start the car and let it get hot......It'll prolly puke again and you'll have no spark...slap in a new coil & try again.

If that don't work, try something else...... (IMG:style_emoticons/default/confused24.gif)

[KitCarlson]

Need4speed,
Yes that's it. The extra ground insures a ground when the distributor is adjusted. It is installed as you suggest. It is not a replacement however for the internal breaker plate ground to case. The internal ground is often broke burn or frayed in high mileage cars.

Ground is required because: The coil is tied to 12V via the ignition switch, the point or Pertronix completes the circuit to ground (where the (-) battery is connected) to charge the coil during the dwell period. Ignition happens when the points open. If no ground at points, coil never charges.

J P,
Excellent idea! It might be the coil. As it heats up internal shorts can happen. Coils can also be damaged by leaving the key "ON", they over heat and the insulation burns on the windings. The oil inside the can insulates at times, expansion or movement with heat causes the intermittent short.

If I was a salesman I would suggest the KitCarlson EMS solves many/all ignition problems relating to the distributor. (IMG:style_emoticons/default/laugh.gif)

Kit

[mike_the_man]

Kit, I have a feeling as soon as you set a price and finish testing of your injection, you'll have a line of people waiting. I'm already sold! (IMG:style_emoticons/default/smile.gif)

[ChrisFoley]

In my experience the Pertronix either works or it doesn't, no in between.
The coil is more likely the culprit.

[KitCarlson]

Mike,

Thanks! I needed a comment like that!

I have parts for 50 units on order. I hope to start selling in 2-3 months. The release time also includes some software that will make setting-up and viewing engine parameters a great experience.

The price will be released once things are firmed up in the manufacturing cost area.

In the mean time I am starting on 6 cylinder applications, Porsche and BMW.

Kit

[anthony]

Sometimes the rotor bottom must be shortened to allow for the space consumed by the magnet assembly. If not the rotor over extends and damages the carbon button in the distributor cap.

I encountered this problem and ruined a good cap. I don't think the solution though is to shorten the rotor bottom. Getting the black magnet ring snapped properly down in to place is the way to go. It took a lot more force than I had imagined. The rotor should go on fine with plenty of clearance after that.

I think the basic problem with the Pertronix is that it's a generic VW fitment and it doens't fit that easily into a 914 distributor. You'll also find that the plastic gromet doesn't fit in hole we have in our distributor housing.

[McMark]

I have installed 3 or 4 Pertronix over the last six months, and I have no complaints about the fit. The magnet ring takes a little while to seat down fully, but if you're persistent it always will and you don't have to modify your rotor. I've always gotten the rubber grommet into the hole in the body. Everything works right, it just takes time and patience to make it fit right.

[anthony]

Did you put them into a 2L distributor? There is no way the gromet I got would fit in the hole.

I will also add that I disassembled the top end of my 30 year old distributor, cleaned out all the gunk, regreased it, and operation improved 100%. My jumpy timing completely dissappeared.

[McMark]

Yes, but as far as I know the distributor housing is identical. The only difference between models is the advance curve and the vacuum unit.

[zehrschnell914]

Ok, here's the update:

I checked the ground strap on top of the tranny and it's fine. The gap is still good on the pertronix and the sensor ring is still all the way down. The dizzy is all the way down as well.

I checked the resistance between the Pertronix plate and the engine case and got .6 ohms consistantly (is this ok Kit?). There is no ground braid in the dizzy though (new .050 so no vaccum advance).

I have had the ignition on for short periods of time when the engine wasn't running (while troubleshooting my fuel pump problems). Perhaps I burned up the coil.

There is corrosion on the inside of the dist. cap (less than 100 miles on the cap...). I have no idea what that means.

I can't get any spark now even when the engine is cold. Is there a way to test the coil to see if it's the problem?

Mike

[McMark]

More likely a pertronix than a coil. The only test is to replace it. (IMG:style_emoticons/default/sad.gif) Did you check for 12v at the coil? Could be an ignition switch going out.

You don't have spare coils? Isn't everybody supposed to have loads of spare parts? I was pulling some engine parts for my crank (at the machine shop getting balanced) and pulled out one of my engine boxes. There was 4 engines worth of misc pieces in there!! How the heck did I get so much crap? Nice to have though. I also found a never cut flywheel (I had 5 spare flywheels at my storage place) so I can stop worrying about my nearly gone flywheel. SCORE!

(IMG:style_emoticons/default/biggrin.gif)
(IMG:style_emoticons/default/beerchug.gif)

[zehrschnell914]

More likely a pertronix than a coil. The only test is to replace it.  Did you check for 12v at the coil? Could be an ignition switch going out.

I just replaced the ignition switch (had some burnt wires under the dash...), but I didn't remember to check for power to the coil (IMG:style_emoticons/default/blink.gif)

Glad to hear about your spare flywheel Mark!

I'm gonna go buy a new coil after I check to make sure it's getting 12v.

Mike

[McMark]

Aha! The story gets interesting. Burned wires you say? Veery interesting. How was the repair done?

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