Blown Coil?

[t-west]

So I'm running rough, especially in the mornings (probably choke related), but I decide to check my plug wires. I pull number 4 while it's running and the car dies. Now nothing. Did I blow my coil? I've cleaned & regapped my plugs and made sure my wires are on tight. New plugs, coil, DSII with module, wires about 4 months ago.

best,
--tom

 

[rbohm]

8) first make sure that you have power to the coil and the module. check also that you have power through the coil, and that the grounds are good. then you can check to see if you have a spark at the dist. if not then either you have a bad module or a bad coil. if so then check your cap and plug wires, and plugs.

 

[t-west]

I've got power -- the pre-resistor wire to the module also piggy backs to the coil -- but how do I check coil output? Do I pull the coil to dizzy wire with the key on, or does someone need to be cranking it?

thanks.
--tom

 

[pedal2themetal45]

HAY TOM
yes someone needs to be cranking it to see if the coil is working.. pull the wire to the cap from the coil and put it near metal or ground spot and watch for a spark... you might check to make sure the coil is getting power when in the cranking posistion theres a start circut and a run circut.
tim

 

[JackFish]

A remote start switch is a cheap handy device.

 

[t-west]

Sorry to bother.

So, if the coil has spark to the dizzy, does this mean my module is bad? If not, what else should I be looking for?

Other than the stock Wells and the $169 MSD, what are our options? Does anyone make a less expensive multiple spark discharge module?

thanks,
--tom

 

[rbohm]

8) if you have spark at the coil, then the module is ok.

 

[hasa68mustang]

my car ran rough for a second then didnt have spark but my cam went through the timing chain cover... do you have spark to the wires?

 

[t-west]

I'm still not sure how I check whether it's the coil or the module. If there's no spark at all out of the coil, does that inherently mean the coil's fried? If the module were going bad, wouldn't I get an initial spark from the coil, then no follow up.

I have nothing coming out of the coil wire, though I'm showing a full 12V to the coil and module.

Oh yeah, and if I get a new flamethrower coil, am I looking for 1.5 ohm or 3.0 ohm resistance?

thanks again to anyone who had been here before.

--tom

(ps, cam seems to be where it should be!)

 

[JackFish]

Measure the resistance of the primary windings. Should be lower than one ohm.
Measure primary to secondary, resistance should be higher, but not infinite.


Read it in a book

 

[rbohm]

8) if you get 12v out of the coil, disconnect the negative coil wire, and check from that terminal to ground, then the coil is good. might be weak, but still good. if you get no voltage out of the coil, then the coil is bad.

 

[t-west]

Thanks, now that I can understand. I did that, and there is a strong reading from the negative to ground, so it looks like the coil is good, the module is bad.

What would make a stock module go bad like that? Grounded? Vibration? Heat? It's only 7 months old . . .

Wish MSD's were less expensive!

--tom