My Evo8 keeps killing COP Denso coils. It misfires under load once a coil has gone bad. I built the kit myself with the correct connectors, a proper crimping tool and good shielded wire.

My car is mostly stock with just a filter, TB exhaust, and 214,500 miles on the odometer, running stock boost levels ( with a slight creep to 21psi). She's been well taken care of as far as maintenance items go, as it was my daily driver for the past 100,000 miles. WB02 shows typically rich under boost for a stock tune Evo.

I've read a few threads where owners mention bad harnesses, but my COP harness has good continuity and doesn't falter when I bend the wires and connectors looking for faulty connections. Is there another test I should try on this harness or the remainder of the factory engine harness?

Everyone suggested checking the spark plug gap. Mine are all at the low end of the range, 28. They're NGK Iridiums with about 35,000 miles on them. The first coil died when the plugs had about 20,000 miles on them, and the most recent coil died at around 30,000 miles on the plugs. Since then I've been running the stock ignition and it doesn't misfire.

Anyone have suggestions for this problem? I'd really like to use the COP coils again as they vastly improve low RPM drive-ability on my car.

Thanks!

 

I switched to copper plugs and change them often. If your running stockish boost levels BR7ES i would think should work fine.

 

Sorry, misread. Do you have picture of your failed coils? I suggest checking your black ground wires. With the COP, you changed the pathway of how the spark moves. The OEM travels from one spatk plug to the other is the system (1&4 or 2&3) and returns to the coil (see diagram).


With COP, it comes back through the ground wire (there has been many arguments on this). Try increasing the thickness of your ground wires to the COP as a start.

When I build mine to test, I will add a wire to screw into a 10mm bolt on head to make sure I have a solid ground.

 

Thanks for the suggestion.

You were having a similar issue as well?

 

Here's a pic of three, the one on the left is still known good, and the two on the right misfire when isolated. There is no warping, bulging or otherwise overheating happening. I have melted coils on prior cars when I set the rise/fall option on a Motec incorrectly. Melted a pair of AC Delco (vette) coils and they looked obviously melted. These Densos aren't overheating as far as I can tell.

I test these by installing one of the factory coils for cylinders 1&4, then I run the COPs on cylinders 2&3. I then swap out coils until I find the one that misfires. I've also swapped this test around using a factory coil on cylinders 2&3.

OK, so you're suggesting I literally drop another ground wire from each side of the coil harness right to ground on the engine block? Just making sure I get the concept here. And thank you for the suggestion!

 

Misfiring is just a super common problem with this platform. Its pretty common form once you start modding to switch to coppers and change them regularly. Copper is a better conductor then Iridium (way cheaper too) it just doesn't last as long. When my Stock Iridiums started misfiring i just switched to copper and never looked back. I think mine lasted till around 40k miles before they started misfiring.

 

Yes, I plan to connect the ground wires together in each system and add an extra wire to bolt to head. This is just my theory. Good luck!

 

There is one more thing I plan to do when I have time to build mine. It is to stagger the positive wire between the 2 systems. OEM powers 1 big coil. We're powering 2 smaller coils with these COP. The 2 systems fire in between each other, so I plan to connect power to cylinders 1&2 and 3&4 so that instead of 2 drawing power at the same time, it will switch back and forth to minimize the voltage sag from each system. Again, this is only a theory and would be more difficult to troubleshoot when problems arise.

 

There's two listings for the BR7ES, a 5122 and a 6615. Which one should I install? and my god they're cheap!

 

I know right, i just swap them every oil change, because why not lol. Im not actually sure of the difference, I don't have a chart handy to me, but I use the 5534 BPR7ES which is a half a step colder. I think the differences in the models are pre-gap and socket size so you could cross reference mine and see which you should use.

 

I just cross referenced all three part numbers (5534, 6615, 5122) and they are all identical in dimensions. I'll throw a set at the COPs and report back in a day or so.

 

Here we go again, more misinformation.


The circuit isn't completed through the ground, it's completed through the battery. It was covered in another topic not long ago.
Clearly you've got no idea.

Iridium or platinum plugs should be used, not copper.
Iridium and platinum plugs give a better spark due to the sharp points on the tips.

COP coils should be expected to fail, they're a downgrade from stock.
They normally fail from insulation breakdown where the spark jumps through the side of it and straight to the plug tube.
Most denso coils used are a bit shorter than stock and as such they'll never fit right.

 

More misinformation.^^^^


Misfiring is a common problem, just as common as incorrect AFR which causes misfires.
All plugs have copper cores, iridium and platinum plugs only have the tips made of that metal, the rest is copper.
The sharp points give the better spark.

 

Do you have a link or tag I can search? I've been trying for days to find more info on this issue and mostly come up with anecdotal statements.

 

Updated to keep upbeat (sorry about original reaponse):
Good luck getting anything from him backing up what he claims. He never gives a good explanation. Just keeps saying how everything is wrong. I've learned to evaluate everything I read that it makes logic sense.

I don't believe that 30,000 volts will travel through lead and sulfuric acid and come out the other side. I doesn't make sense since there is no metal connecting the two posts internally.
I'll let you know once I see proof of that.