XJ killing coils

[kj69]

Bloody xj coil`s, im on my 3rd one in 5000km.
i changed my original 200 000 plus km coil with one purchased from Rock auto because i noticed a crack in it no other reason,it died after less than 2000 km but over one year .
i then replced it with one from Repco and now it has also shit itself in less than 2000 km also over 1 year old .I have replaced it with another Rock auto unit (different brand ) . Are after market coils just crap or is it my xj ?

[jaffazoom]

not sure on XJ's pre coil pack but I would be checking the voltage to the coil to see what it has. Most single coil distributor ignitions have a coil that works on 8 volts approx. They use a resistor or resistor wire to drop the voltage to the coil.
When you go to start the car the battery voltage drops to about 10 Volts as it's cranking and the resistor feed to the coil is bypassed so you get the 10 Volt battery feed direct to the 8 volt coil giving good spark to fire. Once you stop cranking the coil gets the 8 volt resistor feed. If the coil gets full battery voltage
continually it eventually burns out.

Hope this makes sense and helps out, short of all that I see no reason for the coils to fail other than cheap and nasty parts!!

[alexbrown64]

I think the XJ's tend to chew up ignition components. Distributor caps, rotor buttons, leads, coils, etc... perhaps its the heat under the bonnet.
My engine had some weird idling problems years ago, and we changed out all the ignition components and she has run like a champ every since. I generally change out the cap, rotor and plugs now every few years.
I had an original Mopar coil that crapped out at about the 200,000 mark and the shop replaced it. I only just found out that they put another original Mopar coil back in. This is because i thought i would put a new one in anyway as i thought the one in there was "getting old". When i pulled it out, it was the expensive Mopar one (which still works great), so i am keeping it as a spare.
I went on the Rockauto site and you can pay as little as $6 for a XJ coil.. so perhaps there are some poor quality ones out there. They are bolted to the side of the engine block (my 1995 is), so are subject to a lot of heat. You could run the check that Jaffa has recommended, but i would also make sure you buy a good quality, even Mopar original unit.

Cheers,

[LuluBelle]

A few years ago I swapped all the ignition in my 96 limited I just got all the bits off ebay call me cheap or just living in the bush with no shops but they work fine as alexbrown64 said the coils get hot I have seen people mount them high up on the firewall for that reason and water hope you sort it out
_____ooooo
/__l_l_,\____\,___
l_---l_l__l---[ ]llllll[ ]
_.(o)_)__(o)_)--o-)_)

[kj69]

Thanks Jaffa ill lookinto that.

[kj69]

Originally Posted by alexbrown64

I think the XJ's tend to chew up ignition components. Distributor caps, rotor buttons, leads, coils, etc... perhaps its the heat under the bonnet.
My engine had some weird idling problems years ago, and we changed out all the ignition components and she has run like a champ every since. I generally change out the cap, rotor and plugs now every few years.
I had an original Mopar coil that crapped out at about the 200,000 mark and the shop replaced it. I only just found out that they put another original Mopar coil back in. This is because i thought i would put a new one in anyway as i thought the one in there was "getting old". When i pulled it out, it was the expensive Mopar one (which still works great), so i am keeping it as a spare.
I went on the Rockauto site and you can pay as little as $6 for a XJ coil.. so perhaps there are some poor quality ones out there. They are bolted to the side of the engine block (my 1995 is), so are subject to a lot of heat. You could run the check that Jaffa has recommended, but i would also make sure you buy a good quality, even Mopar original unit.

Cheers,

Thanks Alex , i did replace all ignition parts when i did the coil the first time .

[rainman]

i had this problem, was eating coils, got to the point i had a spare cable tied to the installed one, pull the plugs out of the old one into the standby. like you said got somthing like 2K-5K out of them.

One day my pcm just died. Dead as doornail. Replaced the pcm have not changed the coil since that day.

Xj coils have constant 12v +ve into them, ( from The asd relay) and are fired by the pcm earthing the circuit. They do not ground (electricaly speaking) to the block.

good luck with it.