Several years ago my kids bought me a set of headers (ebay specials) for the car...not something I'd likely have bought myself, but I wasn't necessarily opposed to the idea. A few months later, my older son and I got out the tools and jack and jack stands and, over the course of an afternoon, got them installed.
I'm happy with them, but the downside that was created has been a persistent CEL ever since because, in the process of adding headers, we eliminated one of the two catalytic converters on each side. There are 2 bungs on each header (visible in the pic), but with no cat in between, the readings on the second, 'downstream' one are way off, hence the CELs. I slap the scanner on it from time to time and get codes that are all referable to the headers/O2 sensors. That being the case, other than to check occasionally, I've largely ignored the CEL. The car seems to run fine, no loss of power or mileage issues, etc.
I'm now at 86k miles on the odometer and am starting to conclude I'm about at the point I could use a clutch. It's not really slipping, but the other concern I have is getting an IMS bearing retrofit (or the IMS Solution—haven't decided yet) installed in conjunction with having the clutch done. Problem is, LN Engineering & Flat 6 Innovations are very picky about insuring vehicles getting their IMSB products are in good shape, probably so as to NOT potentially impugn their IMSB product if the car's engine self-destructs due to some other cause. (I don’t blame them on this.) Anyway, as a result, the installers I’ve been talking with are apparently uncomfortable proceeding with a car with unresolved CELs.
I know this was kind of a Mickey Mouse approach, but not having an obvious better option available to me, I attempted to circumvent the O2 sensor using a couple of spark plug defoulers. I actually started with relatively short, straight ones. When they didn’t resolve the problem, I upped the ante and got these angled, longer ones, one of which is shown in the photo below. They didn’t work either. Had one of the technicians at a local Porsche dealership look at them and he assured me they weren't long enough to eliminate the CEL.
Continuing to Mickey the problem, at first I thought in terms of getting a couple more defoulers and stacking them with the first. Having to mess with getting two more bothered me to no end and got me to thinking: What would happen if I drilled a small hole in each of the two defoulers already on the exhaust? I’d start small—1/16” maybe. Then clear the CEL with my scanner and drive for a while. If it returns, go with the next size: enlarge it to 5/64”, again clear the CEL, and drive again. Etc, etc, til the CEL decides not to come back. Long lead-in to a simple question: Anybody think that might work? Mickey wants to know
