If you get a misfire on one cylinder, and you know it's a bad coil, does the spark plug need to be changed?
I replaced all plugs but not coils since tested them and appeared ok. Then while later got cylinder 2 misfire.
replaced that coil. Now got cylinder 4 misfire.
should I assume those new plugs are still good, or should they be changed qgai. And why? Thank you for details.

 

Spark plugs are quite cheap. Considering the effort you put into it, why not replace them all while you are at it instead of second guessing yourself.

 

Because I just replaced the spark plugs couple weeks ago, all 8 of them.

 

thinking remove plugs and coils, clean plugs if blackened due to misfire, install plug and news coil. hows that sound?

 

The plugs should not be bad if you just changed them. I've had a similar issue on other vehicles and it has mostly been the coils. You can switch the coils around and follow the error code to make sure. Just use a marker to number the coils are rotate them all or just in pairs (like 2 and 4 or 3 and 5). If the error code follows the rotation it's the coil. If not, it's the plug.

 

How many miles and what year? If it s high mileage or 6 years or so old then just change all the coils.

Don t mess with the plugs ( or cleaning) if new.
It is possible to crack and new plug if not installing properly, just a thought.

 

Im sure all plugs installed without cracking. Done too many times.
Replaced plugs but no coils since were still working oK. Now looks like they start going one by one.
Replaced cyl 2, now cyl 4 code came up. So looks like they all will need changing.

2011 pan turbo with 70k now

 

Looks like the 6 year mark is actually a thing this time

 

Was hoping they would last more, but there is only so much life in there. Well, off to buy more coils.

 

That s what I d do.

 

How did you test the coil?

I had a vibration issue during startup that would last 30 to 90 seconds, then smooth out. Also was getting DTC code P0421 (Warm up catalytic converter efficiency below threshold on Bank 1). I would clear the code and it would reappear after a day or two of driving.

I changed coils and plugs on the drivers side first hoping to solve the startup vibration and P0421. After the work, I started the motor and was disappointed to still have the startup vibration issue? I then did the coils and plugs on the passenger side, which solved the startup vibration. Have not driven enough to see if P0421 went away. I always thought bank 1 was the drivers side?

I would like to know which coil and or plug was causing the issue. Does anyone know the way to measure resistance on the coils? Primary and secondary resistances, which pins are which? Where can I get a wiring diagram?

Thanks,
Patrick in Santa Fe, NM
2010 Panamera 4S, 78k miles
2014 Cayenne S, 64k miles

 

If i was in your position and having economics being taken into priority, I would pull swap that plug from a known working cylinder and then run the engine again to see if you can isolate it to just the coils... if you get some kind of misfire code on the other cylinder, then you can confirm that the plug is also bad... But typically in your case and in mine, gonna have to just replace all the coilpacks at once... lol

 

To wrap up this story, I originally changed all coils and all plugs. Somehow, the vendor sent me one coil that was different from the others. After replacement, all worked great.

 

What kind of plugs and coils did you use? or would you recommend? Do any of the high dollar ones make much of a difference?

 

OEM & OEM recommended.