'04 MSM - Time to finally ditch the OEM catch can? PCV Issue?
 

For those not familiar with my build thread, I'll try to provide some oil/crankcase info to narrow down my issue

I've got one of Emilio's billet gear oil pumps from Supermiata, recently put a stock turbo back on the car after ditching the GTX3076 build, and have the MSM complete intake and exhaust kit from Flyin Miata ( I still haven't gotten rid of my Fab9 intercooler, so I guess for all intents and purposes I technically have the Little Enchilada kit..? Haha)

I was going to sort out a rattling timing belt idler, and like I posted on the Facebook group, there's oil on the hot side of the intercooler that I discovered while trying to chase the source of the Random Misfire P0300 - What I didn't expect was oil to be all over my MAF sensor when I was taking apart the intake kit to make room for the timing belt issue. My original worry after finding oil leaking out of IC pipe in front of the driver wheel, was that my turbo is bad (and also good god, how loose was that clamp?! my attention span is horrendous) But now I'm seeing there's obviously some crankcase pressure issues going on.

Like the title asks, is it time to ditch the factory catch can setup and replace the PCV? Perhaps ditch the PCV altogether? They're either failing to do the job or maybe I was short sighted with some aspects of the previous iteration of the build when I got a higher pressure oil pump.
https://cimg2.ibsrv.net/gimg/www.mia...c6d9229b2f.jpg

As an added note, because it was asked on FB, the MAF is not routed after the turbo. This oil is making its way into the actual intake tube where the filter feeds into the turbo. The intake tube the compressor outlet and intercooler tubes all have oil in them. Definitely considering the likely possibility the MSM turbo is doing MSM turbo things and needs to be scrapped.

The MSM plumbs-back the catch-can vapour into the intake so that it can be burned off..
The MSM's catch can oil return hose to the bottom of the pan tends to flood on higher-powered MSMs for turns in one direction on the track so some oil droplets get fed back too in the vapor outlet that is then fed to the intake.
FM make a one-way check valve that you can add to the oil return hose to fix this (it prevents oil from the pan going back UP the return hose).
You're unlikely to fill the oil return hose enough to the point where some droplets remain in the catch can with the check-valve and get back into the catch-can's vapour outlet.

The good news is that oil vapor has a significantly lower octane value than the fuel, so you might not have much longer to worry about it. ;)

Ok so PCV valve isn't your issue. It simply sucks vapours from the cam cover directly into the intake manifold runners to be burnt off, so this flow doesn't reach your intake piping and isn't connected to the MSM catch can.
The stock MSM catch can which feeds from the free flowing exhaust side of the cam cover actually works alright but you need to put a check valve in the drain hose otherwise oil can be sucked/pushed up the drain into the can and across into your pre-turbo intake pipe. This is most likely your issue. If you remove the rubber hose from the metal pipe on the strut brace (exhaust side) is it quite wet with oil?
Flyin Miata sell a check valve for this purpose.
Theres recirculating catch cans that "filter" better (but not really in reality) but I'd be doing the check valve first before going down that path.

Imagine the memes. Hunter blows up a fully built motor on a 1.5 mile commute, AFTER he gives up on his GTX3076 :laugh:

I honestly didn't check those hoses, for some reason. I was really focused on tubes from the compressor outlet -> IC piping, and the intake pipe where the MAF sits. I also haven't gotten around to checking the cold side of the IC or the manifold itself - that will happen this weekend when I double check that my injectors aren't part of the misfire issues as well.

Thanks for the prompt responses everyone, poscats for all. I actually got distracted shortly after posting this and made a call to Flyin' Miata instead of foolishly waiting for things to get worse. Cleaned up the MAF and piping as they suggested just to verify the issue was one that came back. Surprisingly they were reluctant to recommend buying a part just yet, but also reminded me I had the check-valve in my cart already. So that's on the way now, just waiting for delivery. For whatever reason I never pulled the trigger, big regret there! Admittedly, I've driven the car to work since my first post because it was nice to be back behind the wheel after 7 years, but I'm gonna hold off until the check valve arrives - as even driving it like a grandpa didn't prevent the oil from misting the MAF again.

REALLY hoping it's not a deeper issue, because if this turbo is shot it means I could've avoided this step entirely and picked up the Kraken kit when I had extra money from working nonstop through the holidays and selling my Garrett lol. Although, I'm stopping myself from jumping to that conclusion because even after seeing what was an alarming amount of oil, even on the ground, my dipstick still shows full. I assume a lot of that spray was fuel/water vapor adding to the total volume.

offt if you're getting oil spray up the intake pipe towards the maf from a short grandpa drive, you have far worse issues. Compression test time.
Or another test is run a hose straight from the exhaust side valve cover outlet to a bottle, plug the catch can hoses. Go for another grandpa drive and see if you're puking oil out the vent side. If the temp bottle is empty but you still have oil up the intake it points to the turbo. If the intake is dry but your bottle is full you have a bad blowby issue.

I wouldn't rule it out. Motor is super low miles, did the break-in procedure without the Garrett connected but I may have shorted myself on mileage because the car has 15s on it, which I'm noticing makes the ODO tick up quicker than an MSM would normally with 17s. I suppose it's a wash, because that means the engine is revving proportionately since the speedo/odo are fed from that little wheel that attaches to the trans - so maybe just turbo. I won't guess since I have a brand new compression tester in my toolbox. The car sat for 7 years so any number of issues could've come up.

Gonna let the car sit in the meantime though and wait for the check valve since I test at operating temp. Really don't want this expensive ass motor to run more than it has to until I figure out what the issue is.

Update, just installed a new OEM PCV and that Check Valve. Went to clean the MAF thinking it would be soaked again but to my surprise it was bone dry. I may have over estimated how much oil vapor made it into the MAF tube from simple drives. It probably has been accumulating for 2 or 3 weeks. This car makes me borderline neurotic after learning from mistakes I made early on in my build.

Still has a weird idle, gonna get around to redoing the timing belt now that my "new" FM cam ninja tool came in (I was really nostalgic over the metal one I lost after letting someone borrow it, and found one on eBay). I can hear one of the pulleys behind the timing cover making noise. Likely didn't torque it correctly the last time I did my crank seal. Beyond that, and cleaning my injectors, only other thing I could think that's causing my idle issues is either the fuel pump or the fact it still has the original fuel filter

Yeah I really want to. I have a Mishimoto catch can from my first attempt at a build on my 1990 before it got totaled in a wreck, it's still brand new in the box. Been considering throwing that on. Either as an added can to supplement the stock system or just a full standalone catch can. It's got a threaded Allen head screw that seats flush into the bottom of the can, I'm not sure if I can turn that into a return line. I imagine it's just a drain. But the can itself separates from its lid, so I assume the screw has multiple potential uses.

Old PCV I removed wasn't clogged, so I think I'm good. The new one I installed was just a "why not" move. Haven't removed the valve cover but the engine is freshly built technically so it's not high on my suspect list yet especially now that the MAF isn't getting oil soaked anymore like I expected it to. Even before installing the check valve and PCV. Such a strange car

https://cimg3.ibsrv.net/gimg/www.mia...adf43b0edb.jpg
Cylinder #1
https://cimg8.ibsrv.net/gimg/www.mia...6301a39bae.jpg
Cylinder #2
https://cimg3.ibsrv.net/gimg/www.mia...dbc579d5b8.jpg
Cylinder #3
https://cimg5.ibsrv.net/gimg/www.mia...95101de027.jpg
Cylinder #4
https://cimg8.ibsrv.net/gimg/www.mia...6ce7b6c9f1.jpg
Considering the mileage is less than 75mi, these spark plugs look horrendous to me. Maybe I'm wrong. And yes that's a bit of what appears to be oil residue.

Also - I can't get a decent pic but there's definitely some carbon build up on top of my pistons. Black, flaky looking residue and various black specks. Car must've ran way too rich during engine break-in before it sat all these years. My apologies for not being able to articulate how bad the carbon is in specific terms, but the pistons raw finish is still somewhat visible. Just something I noticed when I checked after removing the plugs.

Burning oil will generate carbon quicker than running rich will.

Hmm. Leaky valve cover gasket is my next suspect 🤔
Unless the infamous Supertech valve stem seals are doing what they're best known for lol. There's just no signs of smoke anywhere, it's making it difficult to track this issue down. Plugs weren't soaked, but near the crush washer I think two, maybe 3 had oil. Leaning toward gasket at the moment.

Good news: found the most likely source of my misfire issue.

Bad news: while the turbo side of my kit is no longer producing an oil monsoon, the intake manifold side looked like this when I removed the intercooler and the IC pipe coupler lol. So even though I got to the problem rather early, I severely underestimated how much got passed the IC fins during that first drive. Borescope will be here today, so that'll give me a better idea of piston condition.

https://cimg9.ibsrv.net/gimg/www.mia...f051f038b2.jpg
This stain is post-clean up, immediately fell out of elbow that connects to the IC when I removed it

https://cimg4.ibsrv.net/gimg/www.mia...22f2043887.png


https://cimg8.ibsrv.net/gimg/www.mia...0328f71599.jpg
In the very bottom you can see a minuscule bit of oil hanging out behind the TB

have you done a leak down test yet?

my MSM had similar issues when I first got it. I tried a lot of the easy fixes, the catch can return side one way valve, rebuilt the turbo, etc etc. I think all were contributing to my oil burning issue, but for me, it ended up being deeply scored piston walls. It still made good compression (the rings wore into the grooves) but failed leak down. I was pressurizing the crankcase and pushing oil into the case vent/intake. I had to dump a few cans of brake clean through the intercooler to get all the oil out, it was nasty.

Not trying to scare you, but a leak down test will help rule out some possible sources of your oil issue.

*edit* sorry looks like you're confident you got the issue. I would still do a leak down anyways!

No, in full transparency I haven't. The motor is so fresh that I hadn't considered it once I saw all the oil on the intake side. It's definitely something I want to complete, I just haven't found any mechanics around here I have rapport with yet. And none of the local parts stores seem to have one I can loan out for the day. I'm gonna buy a kit just to keep it the issue pops up since I already made the decision to buy a compression tester back in August instead of renting it.

I got my borescope paired with my phone about 20 mins ago and my replacement lower timing gear just arrived in the mail too so all that's getting knocked out over the next few days, with checking for detonation symptoms as a top priority.