Topic: Yet MORE coil problems...

[aw12345]

You could always try this run a wire from the ignition switch to a ballast resistor then to a stock coil gap plugs to stock gap check distributor cap contacts and go from there

[jfrabat]

You could always try this run a wire from the ignition switch to a ballast resistor then to a stock coil gap plugs to stock gap check distributor cap contacts and go from there

Well, I am currently running stock gap (I thought maybe that could be causing issues, so I went back to that, but to no avail), and I installed a new cap before I left to Panama last time.  I think I'll try the ballast resistor, but I hae no idea where to get that here...

[jfrabat]

I have not yet found a ballast resistor locally, but I did get to thinking a bit last night...  If the relay for the horn worked randomly, it IS possible that the ASD relay was doing the same. So I went to day to the local dealership, and bought 2 new relays (they only had 2, so I bought both of them) and a Mopar Coil.  I will replace the relays for the fuel pump and the ASD with the ones I got.  I also got one more equivalent Bosch relay (these have the resistor built into them) for the horn, as the one I put there before did not have the resistor. 

I also ordered this ballast resistor from Amazon, but I now have to wait for it to arrive.  I'll keep it in stock, and if I fry the coil again, I will install it somewhere in the engine compartment. 

Felipe

[aw12345]

In case of sticking relays and them somehow staying on, then the coil would be warm to hot still after it sits with the engine off for several hours or overnight

[jfrabat]

In case of sticking relays and them somehow staying on, then the coil would be warm to hot still after it sits with the engine off for several hours or overnight

Now that I never tested...

[sharpxmen]

anyone know what's the impedance on the Jeep coil?
some vehicles have bypass ballast resistor on crank and thru resistor on run (to compensate for the voltage drop due to starter current) - but that would point back to the PCM or some weird wiring issue if there's some integrated resistor and is always bypassed. Some coils are just meant to run without it, not sure which one the Jeep is. For the record there is no external resistor on the YJ.

[neale_rs]

Just throwing this out there:  Could it be a ground problem?  Does the PCM provide a ground for the coil like it does for a bunch of other things on a YJ?

[jfrabat]

OK, I want your opinions.  I already got me a ballast resistor, and I got this one:



Mallory - 700 - Ignition Coil Ballast Resistor - Goodies Speed Shop

Ignition Coil Ballast Resistor; 200 Watt; .75-1.5 Ohms; Variable Resistance; w/Threaded Terminal Connectors; For Use w/E-Spark/MBI/Unilite Distributors. Two Hundred Watt Rating. Threaded Terminal Connections. Improved Cold Weather Starting.

Now, I also have the new Mopar coil, and I also have a spare ECU in the Jeep.  My plan is this:

1. Replace the current ECU with the spare in case that's the problem
2. Replace the current coil with the Mopar (stock) coil

Now, the old coil (the one I fried on the way to Costa Rica) seems to have cracked the plastic at the pulg side.  I will try to get some pics up for you guys, but something is CERTAINLY wrong there...  Also, the fact that I have a hard time if I try to start the Jeep immediatly after I turn the engine off (say, like when you stall it), tells me that I am DEFENETLY having some problems with the ignition (if I let it cool off for about 5 minutes, then it starts without issues).

Now, regarding the resistor, I plan to use it if I burn another coil, so I may just mount it now and have it ready to go in case I need to change another coil in the middle of nowhere (I'll just carry some blade conectors in case I need to repair on the road again), but I am a bit worried that it will make starting the Jeep problematic (I read this is a sideeffect of these resistors).  Now, from what I read, the ones with variable resistance are the best, as they adjust to the conditions, so that's what I decided to get (hope I did not screw it all up!).  Oh, and plugs are gapped at stock gap (.035").  My question is, would you guys advice me to install the resistor now, or wait until it fails again?

[neale_rs]

My vote is for try it now.

[aw12345]

Originally they had this stuff rigged so the ballast resistor is by passed when starting you could tie a relay into the starter solenoid wiring so when cranking the coil gets 12 volts but when running only say 9 volts or so that's basically what it should drop down too with a ballast resistor

[neale_rs]

It could be wired to get those voltage changes based on the START and RUN positions of the key.  START, bypass the resistor and RUN, have the resistor in the circuit.  It seems the voltage drop will depend on the relative resistance of the ballast resistor and the coil.  Do all coils have about the same resistance?

[sharpxmen]

if it craked where the wire goes in i would replace that wire with a stock one (my thinking is it's wasting spark over there and that's why it cracked).

It could be wired to get those voltage changes based on the START and RUN positions of the key.  START, bypass the resistor and RUN, have the resistor in the circuit.  It seems the voltage drop will depend on the relative resistance of the ballast resistor and the coil.  Do all coils have about the same resistance?

you can't really, it's powered by the ASD and not the start/run key switch (i wouldn't mess with that to be honest).

[neale_rs]

With the ASD involved it sounds like it would be pretty hard and might not end up very reliable. 

The cracking does seem pretty significant.  If it is arcing at the wire and at the plug, it might be too much resistance to ground.  Could this cause a coil to fail?

[jfrabat]

With the ASD involved it sounds like it would be pretty hard and might not end up very reliable. 

The cracking does seem pretty significant.  If it is arcing at the wire and at the plug, it might be too much resistance to ground.  Could this cause a coil to fail?

I'll see if I can get some pics of the coil up today...

[neale_rs]

Found this:

http://www.ehow.com/list_6387940_ignition-coil-problems-symptoms.html

Overheating
One of the most common causes of ignition coil failure is overheating due to excessive spark gap. Spark plugs that are gapped excessively large require additional voltage for the spark to jump from electrode to electrode. This causes additional load on the ignition coils and subsequently causes the internal coils to heat up. During the excessive heating and cooling process, the coils expand and contract each time diminishing their integrity and causing malfunction or total failure.

This pretty much confirms that having some arcing in addition to the plug gap could cause overheating problems.  It also mentions expanding and contracting, which sure seems like it could cause cracking.

Have you tried looking at the engine running in the dark? I've detected bad plug and coil wires this way several times, you just see the sparks at night.