Strong Start and DEAD. Stranded without spark at coil!!
 

Drove the '78 to work this morning, ran hard and fast, didn't skip a beat.

Just went out to grab some lunch and take the long way back. Car started 100% normal, ran strong for about 20 seconds and just shut-off...like I turned it off. No sputter, no hesitation, just turned off.

I checked fuses, ground strap, plugs, coil wire, wires from alternator, CDI is making noise, cranked it more and all I was getting was a strong eu-de-87-Octane. I pulled the coil wire off and checked for spark (yes, I know it's a no-no) no spark.

I have a hunch as to 2 things it might be other than a bad coil.

Bad relay 911.615.115.00 (found under CDI cover) or possibly the tach limiter wire? The one that would cut the engine when rev limiter is hit, as the car cut out that abruptly.

HELP!!?? THOUGHTS!!??

Disconnect the battery, slow count to 10, restart...

????

You can measure the coil pretty easily with a DVM: Disconnect it and measure resistance between the two terminals (~ 1 -2 Ohm) and then measure resistance from one of the terminals to the center HV terminal (1 - 2 kOhm). That will tell you whether its the coil or not.

Next, the trigger signal from the distributor could be missing. This is a common issue when the green coax wire disintegrates due to heat and age. It can internally short. Inspect it for no cracks. Not really easy to measure unless you have access to an oscilloscope.

Next, the CDI box is suspect. If it whines that is not sufficient to tell whether it works. Its the other way round: if it doesn't whine it is bad.

Even when it whines it could be internally short (whine is higher pitch, around 4.5 -5 kHz, than normal, 3,5 kHz) You need a trained ear to be able to tell. Else it could have another defect that prevents it from releasing a spark.

Ingo

Will do:)

I posted the same as Ingo but it didnt upload for soem reason , he is pretty well dead on .. my troubleshooting is simlter tho..

1. if its a silver brazillian coil .. thats the problem , throw it out ...

disributor pick up and rev limiter are possible but down lower on the list of probabilities ..

if you have a spare pop in another coil . if thats not it find a buddy and swap out the CDI BOX.

just like the phrase all that glitters is not gold .... all that whines is not always working ...

Good Luck .

Trigger wire doesn't look all that awesome...

Being that all of these parts are original, coil, trigger wire, cdi...I think I'm simply going to order the 3 and go for a "while you're in there" kind of refresh, instead of fixing one of the issues and chasing more down as they present.http://forums.pelicanparts.com/uploa...1412004047.jpg

Why are you running 87?

i would not do that. if anything, i would have the CD rebuilt replacing the old capacitor. as for the dist and coil, what you have is probably better than what is new. go get an MSD coil and just carry a spare coil and if you feel the need, carry a spare CD unit. as for the dist, i think NAPA carries the coil that goes inside but as far as replacing it on the road, that would be a bit of a task. at least you would have the part though.
clean up the wiring and make sure it is not brittle and cracked.

Because he has 8.5:1 compression.

That's a big plus 1.

If you want to throw parts at it, go buy a new $18, 1967 Chevy coil and throw that on.

Next purchase S/B a multimeter.

Green wire is expensive and a PITA as you will need additional connectors. The coil thingie inside the dist is cheap but very easy to test. If you test resistance through that distributor coil (unplug the CDI six pin from the CDI and touch the green core and shield at the connection you have in the picture) it should be in the 575-ish range.

New random thought through reading...

Was reading on Perma Tune website. They say that if your coil goes bad, the CD box is destroyed...

True? (Just seems like that would "make sense" for them to say considering they're supplying new boxes.)

I am definitely going to buy a new coil, already got the multimeter. :)


Also, does the dist need to be removed to replace the trigger wire? Looks awfully close.

yea, you cant get to the screw on the side to unplug it.

do you have a perma tune?
i prefer MSD. the new MSD has an LED light on the side that flashes when it gets the trigger from the dist. could be a VERY VERY big trouble shooting aide on the side of the road....or at home. MSD also has a dial in rev limiter.

i am not sure of exactly how yours is wired, but from the pic, is that how they did the 78?
looks like someone fab'd something to make it work. (IE, not original).

just as a thought. i wanted to keep my 930 wiring harness original. i had to replace the wires to the coil. instead of cutting the sheething on the harness i was able to pull in new wire using the old wire to pull it. sprayed a little silicon in there to help them slide.


from the pic, that part of the green wire does not look that bad. you may want to splice it there if you need to splice it.

Legacy Permatune boxes do not stand up well against imperfections in your cars electrical system.

On the Permatune site there is a diagram of the six pin connector. Measure the ohms between trigger and shield wire. S/B 575-ish. If so, you can drop the green wire variable.

Also, if Permatune, she may fire up now. If it does, do not hammer on the car. That can beat on the box causing it to quit again on the way home.

I'll try and exercise my sideways flat-head unscrewing capabilities...

No Perma Tune, just reading about options. Just thought it was strange as i check with a few buddies and read a lot on here, nothing eluded to a bad coil wiping out the CD box.

If it comes to needing a new ign, i'll be going with the MSD :D

There's plenty of "not original" I keep finding. Bought a green wire regardless, as parts prices continue to rise and eventually I'll make it right.

I really just want the car running again, season is coming to a close and I've done less than 600mi this year!

I found that diagram and am planning on testing tonight.

The car crapped out last Tuesday at work, was towed home DOA last Tuesday night

Just did some searches. Ohms s/b around 600. Thing is, I don't know where the cut-off is.

I would say no resistance or infinite resistance should raise an eyebrow.

Hey, you get what you pay for. :D

Also, I have never read of the coil pack in the distributor going bad. Your highest risk related to green wire/coil-pack is continuity/ground faults.

Exactly. One of my "buddies" used to build SBC race engines and had never heard of that either.

He's now a pre-war motorcycle aficionado.

I would have the CDI tested rather than buying a replacement. There's a known failure mechanism where it stops working under temperature. And that can be repaired.

Cheers
Ingo

I was going to go through the hosts repair service if need be.

Pack and send it to Ingo.........
 

911SauCy,

I work a lot with CIS engines and if I ever need someone to check my CDI, I'll send it to Ingo. Or send it to someone you don't know.

Tony

I recently had a intermittant, then no spark condition and after replacing almost everythng via swaptronics without luck, I broke down and troubleshot the problem. It turned out one of the wires (red, power) on the back of the six pin had not been crimped properly and just pulled out but was still held in by the rubber boot so it was not obvious and made some contact until it didn't.

Why would I send it to someone I don't know?

Is there a website for Ingo, I G-Searched them and CDI in a number of arrangements but came up with nothing useful.

Just PM him?


Sent from my iPhone using Tapatalk

the bosch unit is very robust and very good.
a bad coil should not hurt the CD since its really jsut a capacitor discharging into a coil. you can have it rebuilt jsut for reliability but i think all that is replaced is the cap and a few SCR's for some more heavy duty ones if you will.

anyone have any specifics ofn this or is this one of those closely guarded secrets to stop DIY guys from spending a few bucks with a soldering iron over many hundreds at a specilist.

Do search here....all the information on the Bosch CDI is here.....what and how to replace stuff.

will do thanks

Update:
 

With the help of Lovely Mrs Saucy, I was able to get closer to an answer last night.
First things first. In the 4 years I've had the car, I've never fiddled with the CDI box/engine compartment electronics. I unplug the 6-pin and this little 3 pin was just hangin out...not plugged into anything...what's it to? (looks to have a blue and brown wire?)
http://forums.pelicanparts.com/uploa...1414593763.jpg
Then I was able to test the key on voltage at the 6-pin, all good at 12.24 Volts, ruling out bad ignition, wiring or fuse from battery.

Then, with engine cranking (lovely assistant) I tested the VAC across the left-most pins on the connector. (dist pulse shielding and dist pulse input) I was able to get a variable reading while cranking between .900VAC and .955VAC...does this seem right?

CDI testing instructions I found said that if there is no pulse the dist pulse generator is bad. If there is pulse it's likely a bad CDI or coil. Well I just replaced the coil so don't think that's it. However, the instructions kindly left out what kind of VAC reading should be expected.

I believe I've narrowed to the CDI, other thoughts?

I believe the 3 prong plug is for an external voltage regulator.

Well...the car seemed to perform/run just fine without it all of my ownership.

Perhaps I'm living in a fool's paradise...SmileWavy

The measurements on the coil output of the Bosch CDI box are not valid without connecting the ignition coil itself. The output is one side of a capacitor and a high-impedance DVM will get confused. You need a proper load and then the output is nearly zero (unless the internal capacitor is damaged).

Be careful, with a bad internal capacitor this output can produce dangerously high voltage with enough current to hurt you.

Ingo