Posted By: Texas_Charger
Strange ignition behavior - 02/11/12 02:40 AM
Hello everyone,
I have a 71 Charger with a Pertronix ignition system, and an MSD blaster 2 coil. The car was idling and running fine, and then all of the sudden it just immediately died... no stutter, no stumble, it was like someone had reached in and cut the ignition off. When I tried to restart it, I got nothing.
It would crank over fine, and as soon as you let off it would backfire through the carburetor. I tried running a hot wire from the battery to the positive side of the coil (not my idea but it seemed reasonable) and still nothing. No spark to the plugs.
After I took the hot wire off the coil, it began to behave a little differently. It now will crank and crank in the "start" position and when you let off to the "run" you get nothing, but when you turn the switch to the "off" position, as if you are about to take the key out, the engine will jerk and turn a little bit.
Do any of you have any idea what could be causing this? I've got a feeling tonight is gonna be a long night of pouring over wiring diagrams, but any advice would help. Thanks!
Posted By: 71birdJ68
Re: Strange ignition behavior - 02/11/12 02:55 AM
Try putting a set of points back in with a stock coil, that will elimate that stuff.I had a brand new pertonix and it fried as soon as power was applied the first time. Some one told me they would do that at times.They gave me a new one but haven't tried it yet.Crane also makes a brain box that goes under the dist. cap. The other stuff, ck switch and starter relay if its not the ing.
PS. do you have the light package on your charger?
Posted By: RapidRobert
Re: Strange ignition behavior - 02/11/12 04:06 AM
I'd opinionate that the prob is under the dist cap
Posted By: HemiRick
Re: Strange ignition behavior - 02/11/12 04:35 AM
Its not unusual for a Pertronix to throw a spark when the igntion is turned on and or off. I think thats the jerking your seeing.
Posted By: 71birdJ68
Re: Strange ignition behavior - 02/11/12 04:56 AM
Yah, i forgot about that, i had a motorcycle with an after market electronic ing. and every time you turnedd the switch off or on the eng would try to start with out the starter if there were gasses in the cylinders.And if the intake valve was open on that cyl. it would fire back through the carb. Good call
Posted By: Texas_Charger
Re: Strange ignition behavior - 02/11/12 03:54 PM
My charger used to have the hidden headlight package, but I recently swapped them out for regular exposed lights. Does that somehow make a difference?
Thanks
Posted By: RapidRobert
Re: Strange ignition behavior - 02/11/12 04:18 PM
Scratchn said that you do not want to leave the ign on w pertronix but it did die while running. I think the Pertronix just up & died. Reportedly they are very reliable but no system is 100% and it may have been abused or Murphy's law
Posted By: mopars4ever
Re: Strange ignition behavior - 02/11/12 04:44 PM
I read somewhere on the internet that if you leave the ignition key in the on position for a period of time it will burn them out. A friend of mine went thru two of them and decided to go back to points.
Posted By: 451Mopar
Re: Strange ignition behavior - 02/11/12 08:25 PM
If it uses a magnetic pickup, check the gap, and that the shaft is rotating when cranking the engine.
Also, check for a short on the coils "-" side. It sounds like the coil is grounded on the "-" terminal, either a short, or the ignition module. When you turn off power to the coil, the magnetic field discharges into the secondary creating a single spark. Most of the electronic ignition systems will grounf the coil "-" terminal until it senses the trigger, so if the pertronix unit does not sense the rotation of the distribitor it will not release the grounded output which would normally create a spark. It is also possable the ignition coil has an internal short.
Posted By: Texas_Charger
Re: Strange ignition behavior - 02/11/12 08:28 PM
Okay guys, I chased my tail for a few hours and then finally took the petronix off and replaced it with the old points system. Of course it fired right off...
So my question now is, do I need to run a ballast resistor with the MSD blaster II coil until I can get a new petronix?
Posted By: RapidRobert
Re: Strange ignition behavior - 02/11/12 10:08 PM
Lot of grey area on what you can & cannot get by w on ballast amt but w a non MSD I would use some ballast exp as you dont need another breakdown till you get the Pertronix replaced EDIT somehow missed that you said points, absolutely run a ballast 1 ohm or more
Posted By: 71birdJ68
Re: Strange ignition behavior - 02/12/12 03:51 AM
Didn't i say to put the points back in it first thing? Anyway Pertonix units do that at times, they will just pop. If you go back with a pertonix try a pertonix III it is better and has a built in adjustiable rev limiter.Or if you don't trust it, crane has a unit too. You need a ballast so the points and coil will last longer. But i don't know about a MSD .