DSII up and running, sort of

shetland

Well-known member
Just got my DSII running. The original module was bad. When I plugged in the new module (thanks Jack) it fired right up even though the timing was super retarded. I adjusted the timing to 10* advance then set the idle back down and took it for a quick spin and what a difference. Immediate response on throttle and it idles so smooth I can hardly tell its running.
Now for the sort of part.
After my spin I was getting out my tester to check the idle. The car was still running and I heard a loud POOF. I turned around and there was oil all over the side of the engine, the fender, under side of the hood, everywhere.
Closer look it was the coil. Brand new MSD Blaster2 had blown it's top. The entire top of the coil is now about 1" out of it's case. interestingly enough the car never never skipped a beat and was still running.
Luckily I did not have my face under the hood when it popped. The oil and coil were very HOT.
Can someone tell me what would cause this??
Should I have run the hot leg through the ballast wire, although all of the posts say to by pass it?

Dale
 
I dont have any ideas on why the coil would blow especially if its still running. Most of the time its because it gets continuous voltage. If anything running through the resistor should lower the voltage. Perhaps the voltage is too low and the module freaked out and left the power on? Maybe the bad module stressed the coil? How and where did you mount the coil? Seems like there were some details about mounting in the instructions.
 
most likely a bad coil from the manufacturer. It happens. The coil is designed to get 12-14 volts continuously so you can't really blow it up with anything you did. Most electrical stuff that is bad shows up right away.

John
 
Real glad to hear you didn't get that chit in the face! I believe I would have a serious one on one with someone where you got the coil.

CrashBob
 
When I took out the coil the bottom end was puffed out like a soda can that had been shaken. The oil inside must have been boiling to cause that much pressure.
I took it back to Checker and they gave me a new one. I'm concerned that there may be to much voltage or amps runing to it that made it heat up like that.
 
If your 'system' voltage never goes above about 14.5 you should be fine for just about everything. Any higher than that and just about every electric device is going to start to be unhappy. Around 13.5 is fairly typical. My guess is with your earlier attempts and issues you had continuous power going to the coil for long periods of time and thats what stressed it. The reason it happend to blow when it did was just because ambient temps spiked when you stopped after your test drive. With an electronic module there is really not any way the dwell could be too wrong, most of the time the modules either work or they dont. The only wires on the - side of the coil should be the wire from the module and a tach if you have one. If there is another wire there that could be grounding the coil and causing your problem but I wouldnt think it would run if that was the case. Perhaps your timing is not correct also and that can add temp to the motor making things worse. I assume you have it mounted in the stock location at a slight angle on the side of the block?
 
Standing wave into the coil, with just a modulated voltage over the top? That could pop it...
 
Ford Convert-
Yes it was mounted in the stock position on the side of the block and there is only the module wireto the neg side ( no tach). timing is @ 10*.
Are you saying that since the coil was installed with athe bad module that would or could have "stressed the coil" to the point that whenthe new module was installed the coil had had enough. I want to understand so that i can be fairly cofident of no reocurrence.

Addo Wrote:
"Standing wave into the coil, with just a modulated voltage over the top? That could pop it..."

Can you please translate?
Right now cars are like women, I love them to death but have a hard time understanding the lingo sometimes. :?
Slowly but surely I'm learning. :lol:
Thanks for all your input

Dale
 
A standing wave means just a constant voltae, say if there is a wiring defect or an internal fault in the module, that allows a constant voltage (arbitrarily say 6 volts) to feed into the coil - similar to how the coil is powered up when you turn the key on but don't start the motor - remember how it gets hot to touch then?

On top of that, with the motor running you then have the module doing its intended job, or providing a varying voltage wave as the distributor turns. That has a pretty strong signal, so the peak voltages might be heating the coil a little in themselves. But when you add the unintended constant voltage, it's enough to tip the scales and it boils.

An oscilloscope reading of the coil signal would show instantly any problems like this.
 
thanks for the explanation. Unfortunatly I do not have access to an oscilloscope. This is how things are now.
I installed a new coil exactly the same as the previous.
I checked with a simple continuity tester the + & - terminals on the coil and there was no juice.
Then I turned on the key and did the same. the + terminal had full power The - terminal showed a very week steady current.
I started the engine then did the same. + term full current - terminal with ocilating weak current.
While running I put hand on the coil and could feel the coil heating up. It did not get too hot to touch but was getting very warm.
shut off the engine and let the coil cool. Turn the key to run, engine not running, and the coil immediately started to heat back up.
Does any of this info tell any thing or sound strange?
Thanks again for your help
Dale
 
If the red wire and the white wire going to the module were switched what would be the result?
When I 1st installed the red and white were backwards at the connector. red pluged into white and visa-versa. At that point nothing was working and i switched them around thinking that was the problem.
Could that cause what I am now experiencing?
I ran the engine at idle checking the temp of the coil about every 15=30 seconds and within 15 min temp reached 200*
 
The white wire is just supposed to retard the timing for easier starting. If it ran like that it would make the engine run warmer but shouldnt bother the coil unless it also adds a longer dwell or some other sort of boost for better starting. I suppose it could since cranking would be low rpms for short periods.
 
Well, without a 'scope we can't tell for sure - but I am with addo.

If your coil is getting that warm, It sounds like it is running at 100% duty cycle.

Some coils can handle that, some cant.

In lieu of being able to test the signal, I would try a different module and see if the problem goes away.
 
Well it seams that the coil was getting to much voltage when wired direct to the ignition. I rewired useing the original balast and everything is running great. Now I can drive it someplace that can put it on a scope and do a full check of everything. Obviously there is something different on my car that others are not experiencing. I'll let you know what I find.

Thanks to all for your input and help.

Dale
 
It is possible that you have a faulty voltage regulator causing your system to be running at way too high of voltage.
 
I have never checked the electrical system. Until now i never had any reason to believe anything was wrong. if it isn't broke don't fix it. I will be taking it to a friend of mine and put it on his scope to check everything.
thanks for all your help
Dale
 
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