Back in December after going around town in my 03 VIII for well over an hour, I pull off the highway up to a light and suddenly it the idle is very very poor. Doing it's best to stall. I knew the coils in it were very old, so I went on amazon and ordered a couple of coils for about $25-$30 each. I swap the coils out and the problem goes away. But, about a week later I'm facing the same problem again on new coils. I figure out that it's the right one acting up, I get a new amazon coil and put the factory coil on the left. Problem solved for about 2 days, then same thing. I get another brand, one that's Chrysler/Mitsu compatible. Problem goes away for 3 weeks, then on the way home I'm in traffic stalling on the highway. I had bought 2 $30 coils from another source, and swap one in, that lasts 20 minutes before I'm stalling again. I swap to my reserve and make it home on my last coil.

This issue only crops up when things are totally heat soaked like in heavy traffic for a while. Some of the coils start idling 100 rpm's low before things go bad. Sometimes if I can bring the car to a complete stop it will idle normally before going back to acting up soon after. Is it these cheap coils that's causing my issue, or is my 8 killing coils? I don't want to spend $$$ on a factory coil and have it get killed.

Please help, thanks.

 

Is your car throwing any OBD Trouble codes? Have you looked at / tried replacing the spark plugs?

 

Im no expert on ignition but i would never trust a coil pack from amazon or ebay, even if it claims to be OEM. I would buy straight from a dealer or a reputable source. Or go performance aftermarket setup.
I would definitely install a cheap coil on a non performance vehicle tho. But for a boosted car, i can see the stress of high cylinder pressure (opposed to a non performance engine) taking a toll on sub par replacement parts.

 

Hmm. I’m still struggling with this one, today’s coil lasted 30 minutes. I pull off the highway, throw in the clutch, and I’m coasting. I did find a dropped vacuum line on the fuel line. I checked the plugs and they look ok; some signs that it was running lean. The thing is that I’m not running it hard, the coil is dropping out when I am doing things like sitting in traffic, everything thoroughly heat soaked. Same one each time. Either these coils are pure crap or my Evo is killing them. Anyone ever encounter this before? Is there some sort of voltage regulation thing going on that could be involved? I’m about down to buying an expensive coil and hope my car doesn’t eat it.

 

Try hitting a wreckers and doing the COP diy? Uses OEM coils for dirt cheap and an excuse to hit up a wrecker. Super easy to do and work great.

 

First lets understand a few basics.

Ignition coils work by charging a coil by providing it a power and ground, the ground is then removed, which allows the magnetic field to collapse. When the field collapses, this collapses across the primary and secondary coils of wire. Since there are 100x more winds of wire on the secondary, you take a 400v spike and turn it into 40,000v. This is what allows the spark to jump the gap.

If you have an open circuit anywhere the coil has to work very hard- which causes coils to fail. Also- if the dwell time is too long for any reason, the magnetic field is fully saturated and all you get is excessive heat.

You really need to look at the primary or secondary waveforms with an oscilliscope to understand your root cause.

 

I let the dealer have a go at this. They “cleaned all of the grounds” and even added ground wires to both coils(?). Don’t ignition coils ground through the plug/block? When I get it back I drive it in light traffic for about 45 minutes a few times and things seem fine. Then tonight I’m heavier traffic and approaching the hour mark, throw in the clutch and I’m costing again.

I don’t know what to do next; please help.

 

Take the car where someone qualified who knows how to use a scope can look at it.

 

Did the stock coils ever make it back into the car? One would think a dealer would do that, but eliminating potential problems is info the guru types(not me!) need to know.