I replaced my ignition coil not too long ago, and I think it's going bad already.

My question is this - if when I installed the coil, if it was in contact with the intake manifold, could that cause the coil to go bad very quickly? I'm thinking that the heat from the intake caused the coil to go bad.

Thanks,
Matt

 

coils usaully work or not at all, coming in contact with intake will not cause issues with life of coil, but heat and vibration have an effect on electrical components, if that makes sense. what make you think your coil is going bad, lets start there

 

Matt,

Is it a stock coil or aftermarket?

Are you using the stock wiring harness wiring?

I recently had a new Mallory cylinder type, oil filled coil last only about 2 months. I thought my original coil was going bad. Car would run fine cold, but as it warmed up it would develp a miss under a load that would get progressively worse. Turned out to be wiring problem in my harness, not the resistance wire.

Roger

 

The issue I had, and am now having again, is much like what roger3 describes.

I'm running a stock setup.

The car runs great until it has been running for a while, then it gradually starts missing, and eventually won't run at all until it's cooled off.

I replaced the last coil, and put in one of these (http://shop.advanceautoparts.com/web...S_654697728___). It fixed the problem for a while, but now it's coming back, and after I realized that when I installed it, it's a much smaller diameter coil, and it was resting on the intake manifold. I was thinking that maybe the extra heat of the manifold 'fried' my new coil. Is the coil bracket designed to keep the coil away from the manifold for this very reason?

Roger3, I cusious, what wiring issue was causing your issues?

Thanks,
Matt

 

Matt,

The wiring harness next to the starter was routed such that it was only an inch or so away from the exhaust manifold. As soon as I moved it a few inches away my problem was solved.

Trying to solve my problem (prior to moving the wiring harness) I replaced nearly everything in my ignition circuit. I stumbled across the wiring harness issue trying to find the source of low voltage to my coil.

I tried 4 diffent coils on my car. Mallory - lasted about 2 months and quit working. Accell lasted about 3 weeks then quit working. Bought an AC reproduction and installed it. Unfortunately it had a larger diameter than the original but I made it work. Then I discovered the wiring harness issue. I installed the original AC coil that was in the car when I bought it (looks like the original) and it runs perfect.

Have you tried testing the resistance in the coil when it's hot.

Roger

 

Roger,

Thanks for the info.

I got down and looked at the starter wiring. I noticed the small cloth covered wire connected to the starter with the cloth wrapper was frayed.

I replaced the connection, and took the car out for a long drive.

Things went much better, and I didn't see the complete loss of power, but I did notice a small amount of hesitation.

I pulled into a lot and hooked up the voltmeter, and it showed ~9v at the coil + post while running, and ~ 2.1 ohm's Resistance thru the coil. Before i started the drive, I was seeing ~10v, and ~1.6 ohm of Resistance.

So, I am seeing some increased Resistance in the coil, and this is appears to be occurring concurrently with the noticed performance drop.

So, I think I may still have a bit of an issue, but overall things appear to be much better. I'm not sure about the Resistance increase in the coil, and if that's normal though.

 

That coil is one of the better ones out there. I have been running that for quite a few years now. We used to have all kinds of issues with coils goin out utnill we bought one of those. I have had the same coil on the car for about 10 years now. It has been througth alot of autocrossing and high speed events and never given me any problems. I have a brand new one sitting on the shelf that I might not even use since I am trying to switch over to HEI.

 

Try this. When the car is first started you said it runs OK. Pull the vacumn line to the distibutor and see if there is a change. If there is than this is good. After it heats up and starts to miss and run bad try it again. If there is no change and you have vacumn at the hose I would look into the vacumn advance unit that is attached to the distributor. Mine had a small tear in it and when it got hot it would open up and would have no advance to the distibutor.

 

Matt,

Your coil readings seem fine. However, my Accel coil resistance readings were okay but my car wouldn't run. Put in the stock coil and it runs fine. Can't explain it.

Here's a few other things you can check:

1. Moisture in distributor cap - I used to do some 4-wheeling. Occasionally I would get moisture in the distributor. When the engine was cold you couldn't see the moisture in the distributor. When the engine would get hot mositure would rise to the top of distributor cap and the engine would run really bad (erattic missing, no acceleration, etc). Check the inside of the cap once the engine is warmed up.

2. Tiny crack in the distributor cap can cause your problem.

3. I once had a spark plug wire go bad. When the engine would heat up one cylinder would stop firing. I haven't seen it, but I guess the wire between the coil and distributor cap could go bad and stop firing to all cylinders. When your engine stops running, do you still have fire at the spark plugs?

4. Your condensor (if you're still running points/condensor setup) could be going bad. Most of the time the condensor and coil either work or they don't but occasionally you get one that only acts up when it's hot. Now my car runs smoooooth as silk.

Different line of thinking - Are you sure it's electrical. I had a bad fuel pump recently give me a hard time. I was having both electrical and fuel supply issues at the same time, it was a nightmare. I ran a temporary rubber fuel line with a clear fuel filter from the pump to the carb (outside fender well to make sure it wasn't vapor lock) and found that after the car was warmed up, the filter started running out of fuel. Replaced "brand new rebuilt" fuel pump with a new AC Delco unit - one problem solved. Then I got lucky and found the bad wire issue near the starter.

Thanks to other forum members for giving me advice, I was loosing my mind. I had just installed several "new" parts to fix both ignition and fuel issues and still had problems with both so be patient.

Keep me updated.

Roger