fried ignition coil

[dbruce9035]

new 20 circuit painless install 99.9% done. runs great and everything seems to work. the problem is i have fried two coils. both were rated 12v. i think it is happening when i have the key switched to ignition while testing stuff with engine not running . the customer support guy said that was over heating the coil. this has never happened on any other vehicle or boat i have owned. does this sound right? it gets so hot that it will smoke and oil comes out.

 

[Viperwolf1]

Does the harness have an ignition wire resistor?

 

[dbruce9035]

no. the coils is rated for 12v and customer support said that would not matter. the first coil was a 10 year old Jacobs and the new one was an accel super stock. do you think a resistor would help? i think i could just not leave the key on ignition, but if you want to test stuff it would be a pain to have to unhook the coil each time.

 

[Viperwolf1]

With a stock ignition system (points or duraspark) you need a resistor.

 

[broncnaz]

Most ignition coils require a resistor even though they say 12V they are only for a 12V system doesnt mean they can take the full 12V for long periods of time. Even the full 12V coils are usually race only coils as they are only in use for short periods of time. there are some coils out there that dont require a resistor but I believe the accel coils requires one. not sure about the jacobs.

 

[Viperwolf1]

Here's some ignition math. The primary side of the coil has 1 to 2 ohms of resistance. With a solid 12 volts on it the current being applied (and turned into heat with the engine off) is 6 to 12 amps. With a 1.5 ohm ignition resistor in the circuit the coil current is only 3.5 to 5 amps.

 

[dbruce9035]

i just went from 99.9% done to 99%. thanks for the info.

 

[Heus33]

Viper's a good man - helped me out with a similar issue. Great asset to the board!

 

[eric0o1]

that kit comes with a ballast resistor. Install that in line on the wht #920 wire that goes to coil "B+" and you should be good to go

 

[73stallion]

a lot of the older fords had the resistor built into the coil + wire, not sure how. i found this out when a friend's '64 ranchero coil + wire went out. we replaced it and almost burned up a coil because we didn't put a resistor in.

 

[dbruce9035]

that kit comes with a ballast resistor. Install that in line on the wht #920 wire that goes to coil "B+" and you should be good to go

please tell me i do not have to rewire. this is how i did it. it was suggested by customer support to wire the white wire to the ignition module.

 

[Viperwolf1]

If you're using a duraspark system here's a ford diagram that shows the old wires.

 

[dbruce9035]

i do have the ballast resistor in my box. i thought sense the accel said 12v it would be good without it. and the jacob people said their coil did not need it. is it just that the engine was not running, and a 12v coil is more sensitive. i bought a MSD blaster 2 that needs a resistor to be my next victim. i plan on putting the resistor in line on the blue/white wire?
this is on the painless harnes

 

[dbruce9035]

can anyone suggest a coil that could take the heat. that would be the easiest, and keep the wiring cleaner. any thoughts on which is more reliable?

 

[Viperwolf1]

i do have the ballast resistor in my box. i thought sense the accel said 12v it would be good without it. and the jacob people said their coil did not need it. is it just that the engine was not running, and a 12v coil is more sensitive. i bought a MSD blaster 2 that needs a resistor to be my next victim. i plan on putting the resistor in line on the blue/white wire?
this is on the painless harnes

Yes that's where the resistor goes. The current to the coil is normally turned on and off when the engine is running so it is not as bad then but you do not need 12 v on the coil. It used to be an old hotrodding trick to put a switch in to bypass the resistor but it is not going to do anything for you with a stock engine and ignition system. You'll just end up putting more stress (higher current) on that new harness and your coil life will suffer.

 

[RangerRob]

My Accel coil has "taken the heat" for 18 years in Texas, but that is with a Ballast Resistor as recommended by both the Accel instruction sheet AND the diagram you posted from Painless (I presume). They show the resistor inline and also the recommended bypass from the Starter Solenoid "I" post to give you full voltage at startup.

Accel does recommend that you do not leave the key on for an extended period of time without the engine running as that can cause the coil to overheat and fail.

Good Luck!

 

[dbruce9035]

My Accel coil has "taken the heat" for 18 years in Texas, but that is with a Ballast Resistor as recommended by both the Accel instruction sheet AND the diagram you posted from Painless (I presume). They show the resistor inline and also the recommended bypass from the Starter Solenoid "I" post to give you full voltage at startup.

Accel does recommend that you do not leave the key on for an extended period of time without the engine running as that can cause the coil to overheat and fail.

Good Luck!

your not too far from me. i live in hutto ( go HIPPOS). maybe "take the heat "was the wrong question. does anyone know of a reliable 12v coil so i do not have to pull out the wires and redo them

 

[broncnaz]

Shouldnt have to pull any wires just put the resistor inline and mount on the firewall. keep it away from anything important as they tend to get hot. I think some of the E core type coils(80/90's fords) dont require a resistor but I'm not positive on that.

 

[mr incredible]

just unhook the coil , and do your testing as needed . also check for a resistor wire , but resistance wont do you much good if the system is telling the coil to fire . it will only over heat or burn up , if it is being triggered . constantly for long periods of time . once you are done testing , hook it back up . and you should be good to go .. i dont have a resistor . nor resistance wiring . 12volt coil .these days most are rated 12 volts in .

 

[broncnaz]

He already knows he doesnt have a resistor he didnt install it and most coils that are rated for 12V systems still need a resistor. just look at the aftermarket coils most of them still require a resistor. I think the coils heat up for both reasons but probably get hotter when the charge is not released as if the coils was being triggered it would have a small amount of time when heat is not being generated.