Problem w/1993 Jeep Grand Cherokee...Jeep Dealer can't figure it out and won't give it anymore of their time.

Question

It keeps fouling out the ignition coil. In the past 4 months, I have replaced the ignition coil 4-5 times (both at shops and myself).
Detail: I'll be driving along just fine, and suddenly all power just dies (accelerator, brakes, steering, engine. The radio, A/C, etc...still work.) This has happened 4 times since I've owned the Jeep. It won't start again until I get a new coil (obviously.) Then it will foul that one out. The last coil only lasted about 10 miles, and I noticed it got really hot very fast.
So...does anyone know of anything farthur up the chain or whatever that could be fouling out the ignition coil? Keep in mind...it's been to a regular car shop, a specialty Jeep shop, and two actual Jeep dealers' shops. They can never figure it out beyond the coil - I'll take any answers, but it can't be a very easy fix if they all can't fix it.
Can anyone help?
I will award a Best Answer and stars...even if it doesn't actually cure my car.
Thanks for any help!

Answer 1

First of all most coils have an in line resistor (ballast resistor) to limit the incoming voltage to the coil. Sometimes these are in the coil and sometimes they are external. Check it for the proper voltage. The voltage going into the coil should have a specification like 9.7 volts or so. Get the actual specification from a Jeep shop manual and check it out. Secondly a bad ground will cause the current to cycle and overheat the coil. You have some type of voltage condition that is either excessive or intermittent. A good automotive electrician would be the best source. Independents and dealership mechanics electrical knowledge ranges from excellent to poor and obviously you have not been to where one is really good at electrical diagnoses. That is my two cents...

Answer 2

I would Check All Of the Easy things first. Most people Overthing things. Check that nothing is grounding out on the chasis or a wire isnt splayed somewhere. You say its getting hot, so the fact that a higher resistance is present in the circuit is a big possibility. Another Thing thats pricy that is a good idea to check on would be the Engine Control Module. It could be going bad. If you have a Volt-Ohm Meter you can test the Old Coil Packs and see whats really happening to them.

Answer 3

Replace the spark plug wires if they haven't been changed. Bad wires can cause the ignition coils to fail. Also make sure the coil is wired through the proper ballast resistor if one is shown in the electrical schematic for your car. Your local library has Chilton's and Motor's manuals with electrical ignition wiring information. Make sure the right part numbers are being installed. Some engines use different coils even between different cylinders on the engine.

Answer 4

They did have problems with the ignition module 92-95. .Make sure you are putting the right coil on it, there are 2 different coils for your truck. Bad plugs and wires will also burn out a coil. Good luck. Barring that you can ask here as well.http://www.car-forums.com/talk/index.php
There could be a problem with the auto shutdown relay as well. http://www.autozone.com/az/cds/en_us/0900823d/80/15/3e/8f/0900823d80153e8f/repairInfoPages.htm.

Answer 5

I'd like to know exactly what brands of coil packs they are using. Maybe, and this is far fetched that the voltage to the coils is either intermittent or too high. They are tender little expensive snotty things.

Answer 6

I would look at the distributor. It has to be sending to much voltage to the coil and failing it

Answer 7

Could there be a problem with the alternator?

Other terms that might be helpful are charging system, voltage, voltage regulator, diode, and (electrical) shunt.

And it probably wouldn't hurt to visit

http://www.cartalk.com/

Good luck.