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#1
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Bad coil?
Yesterday, my '75 RHD std beetle wouldn't start (It might be easier if
you think of it as a '74 since it has a 34PICT-3 carb and the dizzy is the same as a US-spec '74). It cranks but won't start. Not even a hint that any of the cylinders are firing. This is odd since it was running yesterday, though it did seem to be missing a little. At first, I thought I was out of gas (fuel gauge reads near the top of the reserve area), but today I took the air cleaner off and moved the throttle and there was definitely fuel squirting from the accelerator pump tube into the venturis. So, I started to look for an ignition problem. I'm running the stock coil and distributor but have replaced the points w/ the Empi electronic ignition unit (looks just like Comp-U-Fire). All distributor parts are less than a month old (plugs, cap, rotor, wires, electronic point unit). I just set the timing to 7.5BTDC yesterday. Prior to this it was mistakenly set at 5ATDC. Because it's running an electronic ignition, I'm hesitant to leave the ignition on w/o the engine running for any significant time (more than a few seconds). The instructions say leaving the ignition on w/o the engine running could damage the unit. Here's my troubleshooting so far: I first looked for voltage at the "+" terminal on the coil w/ the ignition on. My digital multimeter reads 11.8v. For comparison, the large terminal on the alternator (with the thick red wire) reads 12.3v. Both seem a bit low to me, but I have been cranking the engine a lot in an attempt to start the car. The car still cranks strong w/o any hint that the battery is getting weak. To test the coil, I disconnected the electronic ignition from both the coil connections (+/-). With the ignition "on" I connected a length of wire to the "-" side of the coil. This would act as my manually operated points. I pulled the coil wire from the dizzy and held it close to ground (intake manifold heat riser). I then grounded the "-" wire for a second and removed it from ground. This should cause the primary circuit to energize and colapse, sending a nice charge out the HT wire to ground... I didn't see anything (this was done in the evening). I was holding the HT wire about 2mm from the manifold. I saw nothing until I let the HT wire touch the manifold. Then there was a small arc. To try and improve the lenth of the arc I wired the "+" side straight to the alternator post to get the best "quality" voltage I could. No change in the results. I pulled the coil from the car with it still wired to the alternator connector and used the alternator case as my ground. Again, I could only get a consistent arc when the HT wire was touching the alt housing. I was able to occasionally get an arc to jump the smallest of gaps (0.5mm), but 1/8" or 1/4" was out of the question. Does this sound like my coil has gone bad? Was the above test acceptable for testing coil output? Could my problem be the battery is too weak at 12.3v? Could the electronic ignition have been too much for my old coil (my meter showed almost 70-deg dwell w/ the electronic unit) and killed it? One last question, if I pick up a new coil that doesn't measure more than 3ohms across the primary circuit, can I add (or make) an external ballast resistor so it won't burn out my electronic ignition? AshMan |
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#2
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Bad coil?
AshMan wrote:
> Yesterday, my '75 RHD std beetle wouldn't start (It might be easier if > you think of it as a '74 since it has a 34PICT-3 carb and the dizzy is > the same as a US-spec '74). It cranks but won't start. Not even a > hint that any of the cylinders are firing. This is odd since it was > running yesterday, though it did seem to be missing a little. > At first, I thought I was out of gas (fuel gauge reads near the top of > the reserve area), but today I took the air cleaner off and moved the > throttle and there was definitely fuel squirting from the accelerator > pump tube into the venturis. > So, I started to look for an ignition problem. I'm running the stock > coil and distributor but have replaced the points w/ the Empi > electronic ignition unit (looks just like Comp-U-Fire). All > distributor parts are less than a month old (plugs, cap, rotor, wires, > electronic point unit). I just set the timing to 7.5BTDC yesterday. > Prior to this it was mistakenly set at 5ATDC. > Because it's running an electronic ignition, I'm hesitant to leave the > ignition on w/o the engine running for any significant time (more than > a few seconds). The instructions say leaving the ignition on w/o the > engine running could damage the unit. > > Here's my troubleshooting so far: > I first looked for voltage at the "+" terminal on the coil w/ the > ignition on. My digital multimeter reads 11.8v. For comparison, the > large terminal on the alternator (with the thick red wire) reads 12.3v. > Both seem a bit low to me, but I have been cranking the engine a lot > in an attempt to start the car. The car still cranks strong w/o any > hint that the battery is getting weak. > > To test the coil, I disconnected the electronic ignition from both the > coil connections (+/-). With the ignition "on" I connected a length of > wire to the "-" side of the coil. This would act as my manually > operated points. I pulled the coil wire from the dizzy and held it > close to ground (intake manifold heat riser). I then grounded the "-" > wire for a second and removed it from ground. This should cause the > primary circuit to energize and colapse, sending a nice charge out the > HT wire to ground... I didn't see anything (this was done in the > evening). I was holding the HT wire about 2mm from the manifold. I > saw nothing until I let the HT wire touch the manifold. Then there was > a small arc. > To try and improve the lenth of the arc I wired the "+" side straight > to the alternator post to get the best "quality" voltage I could. No > change in the results. > > I pulled the coil from the car with it still wired to the alternator > connector and used the alternator case as my ground. Again, I could > only get a consistent arc when the HT wire was touching the alt > housing. I was able to occasionally get an arc to jump the smallest of > gaps (0.5mm), but 1/8" or 1/4" was out of the question. > > Does this sound like my coil has gone bad? Was the above test > acceptable for testing coil output? Could my problem be the battery is > too weak at 12.3v? Could the electronic ignition have been too much > for my old coil (my meter showed almost 70-deg dwell w/ the electronic > unit) and killed it? > > One last question, if I pick up a new coil that doesn't measure more > than 3ohms across the primary circuit, can I add (or make) an external > ballast resistor so it won't burn out my electronic ignition? > > > > AshMan > The Coil could still be good. Without the condensor in the circuit, the spark will be quite tiny. Any coil you buy should state if it needs a ballast. The stock VW coil does not need one. Speedy Jim http://www.nls.net/mp/volks/ |
#3
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Bad coil?
Speedy Jim wrote:
> > The Coil could still be good. Without the condensor > in the circuit, the spark will be quite tiny. > > Any coil you buy should state if it needs a ballast. > The stock VW coil does not need one. > > Speedy Jim > http://www.nls.net/mp/volks/ Thanks Jim. BTW, you have a great website! I've been following a lot of your tech articles to keep my beetle running. I still have the old points/condenser in the glove box. I'll wire it to the coil and give it another go. Will the normal (one person) testing procedures for testing the ignition w/ points work when you have an electronic iginition? This is where you turn the engine manually and see that the coil wire throws a spark at TDC for each cylinder. Will this damage the electronic module? If it will, I may need to reinstall my points just for the test. AshMan |
#4
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Bad coil?
Speedy Jim wrote: > > The Coil could still be good. Without the condensor > in the circuit, the spark will be quite tiny. > > Any coil you buy should state if it needs a ballast. > The stock VW coil does not need one. > > Speedy Jim > http://www.nls.net/mp/volks/ Thanks Jim, you were correct. I wired in the condensor and the spark output was noticeably higher. Easily getting 1/8" sparks to ground from the coil wire. So, the coil isn't my problem. I tried to get the electronic ignition to fire the coil as I manually moved the crank thru the timing mark... no luck. Not sure if the electronic module can be tested this way, but as you will see below, it probably didn't matter. I took apart the dizzy and found that the electronic module had been scuffed deep by the magnetic ring. It was on the opposite end from the hold down hex nut. The gouge was pretty deep and appeared to have gone thru the epoxy and into the underlying circuits. Well, time to break out the old points. My old points were pitted so it was difficult to get the .45mm gap. When I stuck the feeler gauge in there, the raised portion where the contacts were pitted would increase the actual gap. I had to sort of "eyeball it". But apparently it was good enough. I set the static timing at TDC and fired her up. Vroom! That's all I had the time to do tonight. Tomorrow I'll set the dwell angle and readjust the timing. That should hold me until I can get some new points and/or a new electronic ignition kit. Thanks again Jim! AshMan |
#5
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Bad coil?
AshMan wrote:
> Speedy Jim wrote: > >> The Coil could still be good. Without the condensor >>in the circuit, the spark will be quite tiny. >> >> Any coil you buy should state if it needs a ballast. >>The stock VW coil does not need one. >> >>Speedy Jim >>http://www.nls.net/mp/volks/ > > > Thanks Jim, you were correct. I wired in the condensor and the spark > output was noticeably higher. Easily getting 1/8" sparks to ground > from the coil wire. So, the coil isn't my problem. > > I tried to get the electronic ignition to fire the coil as I manually > moved the crank thru the timing mark... no luck. Not sure if the > electronic module can be tested this way, but as you will see below, it > probably didn't matter. > > I took apart the dizzy and found that the electronic module had been > scuffed deep by the magnetic ring. It was on the opposite end from the > hold down hex nut. The gouge was pretty deep and appeared to have gone > thru the epoxy and into the underlying circuits. > > Well, time to break out the old points. My old points were pitted so > it was difficult to get the .45mm gap. When I stuck the feeler gauge > in there, the raised portion where the contacts were pitted would > increase the actual gap. I had to sort of "eyeball it". But > apparently it was good enough. I set the static timing at TDC and > fired her up. Vroom! > > That's all I had the time to do tonight. Tomorrow I'll set the dwell > angle and readjust the timing. That should hold me until I can get > some new points and/or a new electronic ignition kit. > > Thanks again Jim! > > > AshMan > Aha!! Good job. IMHO, simpler is better. Stick with points. (Or at least carry a set of everything needed to convert back if something fails on a dark night on the highway...) Jim |
#6
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Bad coil?
> Aha!! Good job.
> > IMHO, simpler is better. Stick with points. > (Or at least carry a set of everything needed to > convert back if something fails on a dark night > on the highway...) > I keep my points and such in the box the pertronix came in. Stick that in the glove box and you'll never be stranded if the pertronix module goes south. Chris |
#7
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Bad coil?
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#8
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Bad coil?
Berg wrote:
> Even easier in the dark: > Keep a spare dizzy with holddown clamp properly timed, properly gapped > points and a fresh condenser. > This way you only need to remove the 13mm nut for the holddown clamp, > and then swap the whole dizzy, connect the wire from the points and you > are good to go! > > J. Just when I was getting ready to toss that 009 dizzy, there's now a good reason to keep it. Whatever gets you home, is worth packing under the back seat... ) Tony |
#9
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Bad coil?
The question that I have is why did the magnetic ring eat the points
module? Anton Anthony W wrote: > Berg wrote: > > > Even easier in the dark: > > Keep a spare dizzy with holddown clamp properly timed, properly gapped > > points and a fresh condenser. > > This way you only need to remove the 13mm nut for the holddown clamp, > > and then swap the whole dizzy, connect the wire from the points and you > > are good to go! > > > > J. > > Just when I was getting ready to toss that 009 dizzy, there's now a good > reason to keep it. Whatever gets you home, is worth packing under the > back seat... ) > > Tony |
#10
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Bad coil?
Sloppy, worn distributor shaft bearings?
Tony anton wrote: > The question that I have is why did the magnetic ring eat the points > module? > > Anton |
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