ttreat

Car has 93K miles and I plan to replace plugs in a month or so. Is there any value in replacing the coil packs? I know I will get some of the do them while you're in there answers but honestly I don't care if I have to go back and replace one if it were to go bad. I just have never seen any performance gains by replacing old packs on every vehicle I have owned.

Fined

I personally like the combustion events in my engine to be on time every time. A tiny bit of preventative maintenance will keep your engine from experiencing a misfire, eventually.

Wayne Smith

What is your environment? Salted roads can corrode the outer layer and then cause misfires. Dry conditions or simple water not so much.

The coils are either working or they aren't. If you're not getting CELs replacing the coils won't be noticeable.

I've got 120K miles on my original coils ... no problems. If I have a problem later it's easy enough to swap them out. In the meantime, why change something that's been reliable with a potential unknown?

ttreat

I like my combustion timing to be correct as well but do older coil packs lose any performance? If they fail, I will see a CEL misfire and can replace them without much of an issue, right? This PM idea seems to come from the practice of replacing a distributor and plug wires. The distributors typically had mechanical wear that would lead to issues and the insulation in the plug wires would break down due to engine heat and the current passing through them. Not really the same for our 997 coil packs.

BTW, my car has been in SoCal for its prior life so I don't think it was exposed to road salt

dgjks6

I used to only change coils when they went bad. But as my cars started to get more and more mileage I got sick of CELs. So I now replace the coils every other time.

Mike Murphy

Petza914

If no misfires, then no need to change coil packs. Once you have one go bad, that's when I replace them all at the same time. When one is bad, the others aren't usually far behind. They'll usually show initial failures when driving in the rain, as the insulator gets cracked, allows water in and shorts out.

HenryPcar

I replaced mine when I did the plugs. It was one of those to-do while I'm there.
I just don't want to second-guess myself. The job of changing plug son a 997.2 is not difficult, but it requires the car to be on jack stands, rear wheel off, and the mufflers also taken off.

charlie997

My car is at 69K miles and I am seeing some random misfire codes from time to time. I can usually clear them with a cheap ODB reader but I am thinking I'll go ahead and replace plugs and coils. Doing research to see how difficult a job it is.

Mike Murphy

ttreat

I haven't seen any codes so I think I'll take my chances. I will inspect them when I change the plugs and replace if there is any apparent damage or anything that appears to be a potential problem. I do most everything myself so it's not like I'm paying double labor to go back and replace them. It is not my DD so it's not an issue if I have to order coils when I replace the plugs. It also isn't a huge job where you'll be sorry if you spent hours going back. I am basically starting over with any maintenance history so they could have been replaced just before I got it, for all I know.

Most people confirmed my understanding that they either work or not vs. losing performance as they wear.

Mike Murphy

GoldenGorilla

There is no inherent advantage and the coil packs are expensive enough that I don't just want them sitting in my parts cabinet. If there are no CEL indications or misfires, then it is simply a matter of whether the packs are in very good condition. I just changed mine for the 40K service over the weekend and they look very clean. I'd plan to change them at the next plug change only if the engine is indicating missed ignition. That said, it is a pain to get in there and you can't exactly run out and get a set from the neighborhood autoparts store.