(It is a manual) For a few months, I was noticing a single, quick, small miss while going up a hill on the highway. No CEL's and seriously only would be one time every few days, so didn't bug me too much. I honestly thought it may have been fuel filter related based on a few other symptoms I'd had in the past and considering it is a 2011 that I bought used, has 112k and I don't think the fuel filter had ever been changed.

In the midst of those issues and the most recently, my commute changed drastically. I went from 30 miles (on way) highway driving to 10 miles city driving (we moved into the city).

Wednesday before 4th of July, it started and idled just tine, as is usual. I was able to pull off in 1st and drive with no issues; however, as I noticed quite quickly that the misfiring and acceleration hesitation suddenly turned pretty awful, especially at higher RPMs in any gear (though was worse in 2nd, 3rd, and 4th.)

Again, I was tunnel visioned on the fuel filter and literally did no troubleshooting. I bought the OEM filter and replaced it without issue, totally expecting the problem to be all gone. Started it up...nope. Worse than before. Misses all over the place, finally now getting codes - cylinder 1 misfire.

Finally start actual troubleshooting/diagnostics and as I took the coil cover off, I immediately see a liquid in the left center bolt well of the valve cover. It wasn't dark, so i was hoping it was just water, but a quick dip into it was able to determine it was oil. Took out the C1 plug and, as I was fully expecting at this point, it was fully soaked in oil, causing it to foul out. Looks like a valve cover gasket job.

Changed the valve cover gasket 2 days ago, waited 24 hours for the RTV at the half moon section on the drivers side to cure. Changed all the spark plugs while I was at it (Beru). Which leads me to now.

Despite self-inflicted stress caused by the car starting but idling rough AF then dying due to me forgetting to replace the PCV valve back on at first, it drives great. In fact, there is definitely some return on power. Starts up great, has power all through all gears. I even put on the ECS decal I had, which is good for, what, 10 horses or something like that My problem is operating temp idle. I wouldn't say it is fully rough, per se, but is more rythmically rough. It'll idle good for 10 seconds, then bog slightly (which causes a rougher feeling), seemingly fix itself for 10 seconds, then back slightly rough again, rinse repeat. If I give it a little gas and get it to 900-1k RPM, it has 0 problems at all. No check engine light, no codes (well, yet...today was the first day that I drove it further than around the block). Any ideas?

More info: This seems to happen worse the warmer the engine gets. Also, it was not doing this before I completed the valve cover gasket and fuel filter change. It is like a "reverse" surge every so often.

 

Vacuum leak? A common way to check is with any sort of flammable spray/gas, like brake cleaner, starting fluid and so forth. Lots of videos online

 

So problem seemed to be getting slightly worse and this morning I got a code. One that made no real sense. This morning I got an alert on the display to close gas cap, but it went away in like 2 seconds. Thought that was weird. No code yet though. Then this afternoon, starting after leaving work, I get the same really quick close gas cap message and my CEL came on.

Checking the code when I got home, it was a P0442, small evap leak. Yes, this could be caused by bad gas cap, but it didn't sit right with me because I did not have this problem before changing the fuel filter and valve cover gaskets. I checked the gas cap, cleaned the filler opening as well as the cap gasket, put it back on, started it...same issue. I started logically thinking about this. I know 4 things:

1.) I did not have the problem (but had other problems)
2.) Replaced fuel filter
3.) Replaced valve cover gasket
4.) Idling problem started happening

I watched live data and fuel trim level wasn't rally acting like a vacuum leak, per se. I mean, sort of, but not like I would expect. Then it hit me. The gas cap alert, the code..and the fact that I HAD been smelling gas when I stopped after my commute but saw no smoke or anything...the fuel filter ring assembly basically IS a gas cap. Pulled the seat, took the plate off and immediately saw that the waffle holes in the fuel filter housing were full of gas. It was only in those that were in the 9-12 o'clock position, so wasn't coming from the hose. Bingo, I thought.

I have the Schwaben tool and went to tighten it up and was able to turn it a good half additional turn to cinch it down. Maybe it wasn't tightened enough. After I did this, I started it up and let it idle for about 15-20 minutes and was stoked. The problem 100% vanished. It was idling smooth AF.

Since the problem happened more often after I had driven for a few minutes, I decided to leave the body hole plate off of the fuel filter housing and take it to the grocery store. There were no leaks after 20 minutes of idling, so I thought this was in the bag, this was merely going through the motions. Driving to the store, all was smooth at each stop. I was feeling relief at this point. Checked around the filter housing when I got there...no leaks.

However....on the way home, I started smelling gas again pretty strongly. While the mini seemed to idle just fine, when I pulled into the driveway and let it idle, suddenly the problem was back! Took a look at the filter housing and it is leaking...again...only this time, it is leaking from underneath/outside of the ring at the 10-2 o;clock position, quite a bit actually.

So, I am 99% positive this is the final problem I just need to take some time tomorrow and take the ring off and check the gasket and then try to get it tightened just right and hope it leaks no longer.

 

Solved and Now fixed. I took the fuel filter housing ring back off and took a look at the gasket and sure enough, where it was leaking, the gasket had been pushed down below the flange. Super safe!! XD It is the OEM gasket and i know they are slightly bigger, but this thing seems like it was 1/8 bigger than it needed to be. Anyhow, after about 15 minutes of frustrated trying, I was able to finally get it visually sealed properly. I then actually torqued this time based on specs (33 ft. lb. +/- 3 ft. lb'). Idled for awhile, test drove 5 miles and it is running great and no leaks. There is a tiny, slight little blip every now and then, but nowhere near as bad as it was before so that may be some other issue but in any event, this is fixed. Not the most usual reason for this problem, but glad I found it. Not one single part thrown, which is rare!