I have a '75 914 1.7L that I've had for almost a year now. I got it mostly as a 'project' car but I have practically no mechanical experience, and have just been essentially learning as I go. I very rarely drive it, but last week, I was driving it home it suddenly cut out. After stopping, the engine would turn over, but would not start. Upon later inspection with the tow truck driver by holding the HT cable over the engine cover, I determined there was no spark.

So after scratching my head and poking around inside the engine bay a few times, I have come to the following conclusions:

- The ignition coil is a Accel (Super Coil I believe). The resistance across the LT terminals is 3ohms, and the resistance from the battery terminal to the HT terminal is 13k ohms or so (though I may not have gotten an accurate reading and will recheck this in a bit).

- There is a Pertronix Ignitor system in the distributor cap. These I hear are pretty reliable, but the way it was wired was pretty funky. The lead from the battery was connected to the - end of the coil, as was the black wire from the pertronix unit, and a mysterious blue wire that I assume is the tach? The red wire from the pertronix unit was connected to the + terminal on the coil, as well as two black leads (what are these?).

I switched the wiring around so the battery lead, the red ignitor wire, and the supposed tach wire connect to the + terminal, and the black wire from the ignitor and the other two black wires are connected to the - terminal. I read somewhere that the pertronix would work if its polarity was reversed, but would eventually burn out so this seemed like a possibility. Anyway, car still would not start. I tried disconnecting the mysterious wires as well, with the same results.

Then, just now, I went out to measure the voltage at the input of the coil. It was 8.5V or so, which seems about right. I was about to measure the voltage at the - end of the coil, but smelled smoke and noticed that it was coming from beneath the distributor cap, and lo and behold, the pertronix is burnt. Now I am wondering, was the pertronix really burnt out, or did I just destroy it by messing around with it...?

My next step is going to be to test the coil itself by momentarily grounding and ungrounding it directly, but I need to get some leads first.

Just wondering if anyone has any advice, or if they have had similar issues...

Also, if I want to pull out the distributor and install a new pertronix, how can I remove it? Or should I try to replace it with the distributor in place? I assume if I remove it I'll have to redo the timing, or is there a way to avoid that?

Who told you the Pertronix was reliable? Not in my 35 years experience. In my opinion, it rates last in reliability of all the various systems.

If it ran the way it was wired, then it stopped, and you changed the wiring, you've put the nail in the coffin. BEFORE you go moving stuff around, before you do any tests unsupported by facts and knowledge, get on google, as well as this and other lists, and find out what's what. You may have cost yourself a buncha money for no reason. Oh, and get rid of that coil, they're inappropriate for use in a German ignition system.
The Cap'n

also forget the pertronix, get points and a condensor

I have had a Pertronix unit in my teener and I love it. Yes I burned one up by leaving the ignitiion key in with the engine off for an extended period of time, but since then I have not had any difficulty.

My concern is that you were driving your car when it quit (cut-off). In my experience, the Pertronix unit can crack if the ingnition key is left "On" while the engine is not running, but I have never heard of a Pertronix unit dieing during driving conditions. Probably the same with the coil. Usually I notice a coil problem as part of an engine fail to start, not as part of "cut-out" during driving.

I agree that if the Pertronix unit was working previously, once you changed the wiring, chances are you may have fried it now. Take it out and look for catestrophic damage to te Pertronix casing.

You should probably think about returning the wiring to the "known good" configuration, replace the Pertronix unit and the coil (neither are all that expensive) and start diagnosing it from there.

Eric Read

HOW WAS IT WIRED BEFORE?????

I have ran tons of pertronix set ups in a bunch of dif vehicles... I love them. but that doesn't mean something couldn't happen to it. I would throw a set of points in to do all your testing and see if you get spark.... no sense burning another pertronix if something is shorted somewhere else... i wouldn't even go nuts on adjusting just eyeball and check for spark..(wouldn't even run it) then buy the pertronix and reinstall.... check coil for small cracks that may open up when warm.... seen that on tons of things.... return to what was working as far as wiring as well.... sounds like you have a intermittent short somewhere that burnt that thing up... or your wire switching got you somehow... points are cheap to burn out compared to pertronix... i agree with eric the ign key on is no good for anything..... the full 12+ volts (usually two ignition circuits one for run and one for start) it gives at early ignition could overheat and burn anything out pretty quick.... our weld those old points right together that everybody seams to like so much... i say forget points and keep the car running in the 21st century... if points were so great and reliable you would find them under the dist caps of hondas..... Pertronix is the same tech used in any current dist style electroninc ignition... ask a couple old timers how fun it is to set dwell and gap on a old duel point euro dist.... if they say it's fine their lying.....

Good luck!!!!

The previous wiring:
+ coil terminal: RED wire from pertronix, and 2 black mystery leads
- coil terminal: wire from battery, BLACK wire from pertronix, and one blue/black mystery lead.

So if I buy another pertronix, and wire it according to the 'official instructions' it will be wired exactly the way it is now, which is the same as above, with the battery wire and mystery leads switched to the opposite terminals (probably should have just left those unplugged). This is however, the configuration that let the magic smoke out of the current pertronix, so I'd rather not do that. I need to figure out what all of these wires are for sure before attaching a new pertronix.

I think I'll go with points as some of you have suggested, at least for now. But first I'd like to test the coil independently so I can rule that out.

I should mention that the wire that I believed to be the battery wire once gave me a reading of 0.6 volts, and 9-12 other times. This could have been my multimeter acting funny, but now I am wondering if this is not actually the battery wire, and maybe there is just a capacitor upstream that is holding charge. I'll take another reading on all of the wires later (after unplugging them from the coil of course, don't want to fry anything else).

I kinda have to agree with "nolonger...". Get some cheap points, get everything working, then re-install the Pertornix device. The Pertronix, while very reliable in a running vehicle, really isn't a very good item to use for troubleshooting. Why take a chance on burning up another Pertornix set at this point.

Eric

When do you get voltage changes??? it needs to coincide with something ie turning ignition switch to start, having at run location???? or you found your problem: a broken wire or shorted wire... there should be no wires that go to coil with power all the time without key in a run position(as far as i know) chase that wire down through harness and find out if it's got physical issues... you have a point about the capacitor but i don't think you would have one there anywhere if switched to pertronix already??? start back at zero and work forward.... i think your "mystery leads" are your run and start 12v+-... red is power to pertronix... leads are power to coil... 1 maybe a tach....

make sure you have a good battery in your multimeter

So I'm back, after more careful tests.

First I unplugged everything from the coil. I then measured the voltage on EVERY lead with the ignition off, and they're all at 0. Good...

Then put the key in the ignition and remeasured. All at 0 EXCEPT the unknown black wire, which is at 12v (wow didn't expect black wire to be hot). Ok, so that explains how I fried the pertronix.

Then connected this black wire to + on the coil, held the HT cable over the engine case, and tapped - on the coil to ground. The little wire sparked when it touched as expected, but nothing from the HT cable. So, my coil is probably shot?

However, I am SURE the cable that I previously thought to be the battery cable was at 12v when I first checked it, and at 0.6v or something another time, which sounds a lot like a capacitor to me. The condenser is still attached to the distributor, so maybe this i the old condenser wire? It goes into a bunch of cables and I can't follow it, so I can't be sure. If I connect it to - and the hot wire to + on the coil, it doesn't take a charge, but that's to be expected right, unless the coil is firing?

Can someone confirm that all of this makes sense? If so I'll probably just get a pertronix and a coil and wire it the way it used to be wired.

Gonna test the resistance on the primary coil again once I get a fresh battery for my multimeter... what is a normal value for this? I know it varies a bit depending on the coil.

Checked the resistance again.

2 ohms primary resistance, 10.7k secondary resistance.
The spec according to http://www.amazon.com/Accel-8140-Performan...k/dp/B00064P99W is 1.4/9.2k. So that's far enough off that it's probably an issue right?

The odd thing was that when I measured the primary resistance initially, it told me it was 100% resistance. I went back outside and sparked it across the battery terminals, came back in, and it measured 2.0. Any ideas why this would be?

even though the smoke is a good telltale that the pertronix went bad, you could always test it out of the car and check to see if it still switches voltage through the black wire.

Put in a bosch blue coil, new points gapped at .016, new condensor, hook up all wires like they are suspossed to be, start the car and drive it!!!!!!!!!!!!!!!!!!!!! If you want to, put a pertronics unit back in after that and keep the points and condensor in the glove box. YOU WILL NEED IT!

I just got a new bosch blue coil, and did the same spark test that failed with the old coil. It is still not working. I'm doing this by placing 12v on the + terminal, connecting the HT cable to the coil, holding it over the crankcase, and taking a lead from the - terminal and tapping it on the crankcase. I should see a spark from the HT cable right??

The cable itself has a resistance of 3k ohms. Is this normal?

I tried to test the pertronix as well. Attached pertronix black cable to ground on multimeter, and pertronix red cable and multimeter red cable to 12v. Will rotating the magnet sleeve be enough to test it? The voltage on the MM was pretty much pegged at 12 and no matter how I moved the magnet it did not change.

it maybe a stupid question but did you also ground the coil while testing???

I am ssuming you haev read through the Pelican Parts Ignition document:

http://www.pelicanparts.com/techarticles/9...roubleshoot.htm

Please note:

"In order to develop the high voltage necessary to produce a spark capable of jumping the gap in a spark plug inside an engine, a means of storing and concentrating energy is necessary. The device that does the energy storage and concentration is the coil. The basic laws of physics state that a coil of wire (more so when wound on an iron core) is an inductor, i.e. it exhibits the electrical property of inductance. Inductance is the ability of an inductor to oppose any change in the amount of current flowing through it...

...as the magnetic field expands, energy is stored in it. We need this energy to make our spark, and this is how we do it.

In order to induce a large voltage, we need to collapse our magnetic field quickly. Because we can collapse it more quickly than we can create it, it is the collapse direction that we use to generate our high voltage. The energy is still present in the field, and regardless of whether it is expanding or contracting, the magnetic lines of force still intersect the coil windings... the trick is to make the relative motion between field and windings as rapid as possible.

This is done by OPENING the points in the distributor. The points remain closed for a considerable time ( 55 degrees of rotation for each ignition pulse if memory serves) and during all that time the coil is storing up magnetic field energy. When the points open, the current through the coil primary is ABRUPTLY terminated. This results in an almost instantaneous collapse of the magnetic field, with the consequent generation of very high voltage in the secondary winding of the coil. We put this voltage to work for us to fire our spark plugs, and that’s basically all there is to it."

Sooooo, if your points aren't moving quickly, the coil will be not create the high voltages you are expecting.

Eric Read

While testing the coil I grounded it, and then disconnected the ground. This should be the equivalent of the points opening, I thought?

While testing the pertronix, I was not using the coil at all. I was simply measuring the voltage across the pertronix.

take the broken pertronix out of the loop.... did you install points yet??? get everything back to "zero" you a are dealing with so muchmix matched crap now that i can't keep it straight. obviously the new coil is good stop testing it... and it's paid for so use it... wire it in, set the points then test for spark with a plug or spark tester ($10 at any parts place) you got my head spinning on whats good and whats not.....

START AT ZERO>>>>> if it ain't broke don't fix it... so far you've thrown a few unknown good or bad parts at it with out finding 1 problem. it's like why adjust the carb on a motor with the a rod blown threw the case???

Fixed it with new pertronix and coil! It's running beautifully now - I think it was misfiring a bit with the old coil cause it sounds MUCH better. It started up in roughly half a turn of the crankshaft.

nolonger: Yeah I gave up on testing the coil because I figured it must work if it's new. I wasn't really trying to test the coil though - I was trying to verify that my method of testing it was even valid to begin with - which obviously it wasn't. I needed to test with a fatter ground wire than a puny test lead. I realize that I'm overanalyzing the entire situation, but my primary goal here is really to diagnose the problem and learn more about the car. My secondary goal is to get it running again.

It just didn't make sense to me to go back to points after figuring out the wiring scheme. Obviously if the pertronix worked before it would work with one again. I preferred to return the car to its last known good configuration than to introduce an additional variable.

Thanks for your input, everyone.

glad you got it back up and going.... learning is part of the fun.... keep the shinny side up!!!!