My car done broke, please unbreak it <3
TL;DR - Misfires on all cylinders
Disclaimer: I'm extremely amateur when it comes to cars, and have tried everything I'm semi-comfortable trying. Hope I didn't goof anything up :D
These issues started with rare short bursts of hesitation about 9 months ago without any recent work having been done on the car. It didn’t feel like misfires, just a drop in power briefly. Eventually started getting more common ~3 months ago, with a couple misfires on startup that calmed down quickly.
In the past three months, the following has been noticed
The codes I’ve had while testing things out have all been misfire related (when it comes to the engine). For each cylinder, as well as ‘multiple cylinders’, I’ve had ‘detected’, ‘harmful after start-up’, ‘injection shutdown’, and ‘harmful to the exhaust gas’. Screenshot of some of the codes below:
Forums said maybe the PCV diaphragm could be the issue, and I tried replacing it. Managed to crack the valve cover trying to pop the door open and had to buy a new one. I know, it's cheap amazon, but three whole people told me it worked great for them!
Once the misfires started getting bad, I was checking out the tubes and noticed the intake pipe was cracked at the turbo. Instead of replacing the section for $250ish, I got a kit for around the same price so I could hear more pswshhhh noises. After receiving it, I noticed it isn't quite made for this specific year of N18; there's an extra PCV hose going into the intake that I don't see in other pictures using the kit. I plugged it in a spot that seems to make sense, and since it's all pulling back into the turbo it should be about the same thing, besides the position it’s entering the intake… right? Didn’t make the problem any better/worse, but definitely something wonky about it.
Had the interior mostly apart when installing the subwoofers and realized if I didn’t replace the filter right then, I’d never do it. What a pain in the ass it was getting to the access hole
Replaced these when the car started hesitating. Not sure if it was misfiring at that point because it wasn't sputtering during hard pulls, but it was noticeably sluggish at times
I'm pretty sure I was still running the original battery. It felt like the issue got a bit better, but it may be wishful thinking
Changed around every 5,000 miles, doesn’t seem to affect the issues in any way
Put it in with the thought it could be the injectors, but didn’t get through the whole tank out of fear of pushing the issue any further