toplessFC3Sman

Hello Everyone,

This past weekend I was driving my '09 RX-8 in a two-day HPDE (track day) at Grattan, and had a few issues. The first day went wonderfully - no issues, the car worked perfectly, and I had a great time. However, on the second day, when I started the engine, the low oil light was flashing and beeping. I had to add about 2 1/2 quarts of oil to get it back to the full line (I don't know that it was full at the start of the first day, honestly I forgot to check since we were camping at the track and I was busy making breakfast etc before the track went hot), but then when I went out, about 2 or 3 laps in I started getting a sporadic misfire above 6000 RPM or so, bad enough to flash the CEL and cause power to be cut. The CEL was P0302 - misfire rotor 2, and sure enough the plugs in that rotor (especially the trailing) were wet with oil. Cleaned the plugs, reinstalled them, and went for a test-drive and wound it out (on public roads, so I couldn't pin the throttle for too long)... no problems, no misfires, and the power felt fine. However, when I went out on track again the misfire was back on the second lap. At this point I decided to pack up & head home, I didn't want to risk any further damage from a misfire or potentially a damaged oil control ring before driving the car 2 1/2 hours home. When idling leaving the track, I noticed that there was white smoke coming out of the exhaust that smelled very oily. However, winding the engine out on the way home getting onto the highway etc, there was no misfire.

Well, I made it home fine, and this morning I pulled the intake apart and found a bit of oil in the intake system. The accordian tube before the throttle had some trapped in it, and there was a stream running down into the airbox that stained the air filter and dripped out of the hole in the bottom of the air box. I've been cleaning all of this and will get to the UIM in a little bit.

All of this seems to point towards accidentally pouring oil into the PCV system when refilling the oil; the coils are the BHR kit with only 6000 miles or so on it, with new plugs and wires at the same time so I think its unlikely that they would already be failing. However, its possible that the blow-by is increasing, causing more oil to be forced into the intake at high speeds. I know the 04's and 05's are prone to PCV issues - did this extend all the way to 09? Anything else I should check or consider?

I plan on installing a catch can in the line too, does anyone have a suggestion for which? It looks like the Weapon R one that is made for S1's won't fit the S2 because there is a bracket off the back of the air pump with an electrical component sticking back towards the windshield wiper reservoir.

Thank you!

Federighi

iTrader: (7)

Pretty sure there's literally zero baffling inside the Weapon R and is worthless junk imo. You should source a catch can with some R&D behind it. I'm using a custom Radium set-up.

Universal Catch Cans & AOS

I'd also try to make a habit of checking the oil level after each session. Bring some parts cleaner and couple quarts just in case

TeamRX8

iTrader: (25)

if your engine is puking oil, you need a new engine. I’ve been telling people this for 10+!years, but if you want to believe these other people claiming otherwise, then be my guest and continue running your engine in the ground.

Been doing this since April, 2005 and never had any NA Renesis engine puke oil. The only reason it pukes oil is excessive blow-by into the oil sump gallery. Wake up and accept reality already.

Even if you don't want to accept it, that’s the unadulterated truth.
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toplessFC3Sman

Worn or damaged oil seals are certainly a possibility that I was considering, but I think I need to observe what is happening with the engine and oil for a bit longer before drawing that conclusion (and the inevitable work & cost to pull and rebuild the engine). I don't know what the oil level was prior to the first track day (when none of this was observed), but there was about 2000 miles on the oil with only normal levels of consumption, so it may have started low on the first day. The plan is to install a catch can between the oil neck and the intake and see how much accumulates, whether the misfire issue comes back, whether there's oil in the intake etc at the end of another track day at the end of Aug.

On a similar note, it looks like the S2's PCV system is a bit different than the S1's? In a thread on this board for the S1, it looks like there is only a single hose coming off, while there are two for the S2. The top one coming off the oil fill tube has a normal rubber hose with worm-gear hose clamp and runs to the intake manifold after the throttle body, while the second is lower on the neck, is smaller, and has a vacuum-nipple style connector that seems to run to the pre-throttle accordian. Should the catch can be installed on one or both of these lines? I'm inclined to install it on just the larger, post-throttle hose since under all but WOT conditions, this side should be at lower pressure and have the majority of air and thus oil vapor flow; if there was no blow-by air would flow from the pre-throttle side into the sump through the smaller pre-throttle vacuum line to provide some recirculation flow to carry away any fuel or water vapor that evaporates off of the oil back through the larger line further up the neck into the post-throttle port.

TeamRX8

iTrader: (25)

It doesn’t matter. The intake is not sucking oil up from the sump. It’s carried up by excessive blowby into the oil system and then into the sump. You have to understand that a rotary engine does not have an open crank churning around with piston bores directly open to the sump. When you have blowby on a rotor, where do you think that’s going? Nobody really talks about that.

I also apologize for having been a bit harsh in my reply and edited it some. The subject get’s me a bit wound up that after so much time certain people still hold onto false myths and other such nonsense. That’s directed at other long time members that should know better by now, not at you.

A turbo conversion is an exception, because by the nature of compressing airflow into the engine it’s going to create blow-by. However, even then when the oil being collected starts increasing then the obviousness of what that means should be apparent.
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toplessFC3Sman

I understand that in a rotary there's no churning crankshaft in the "crankcase", but oil is still squirted into the rotors from the e-shaft where it is spun around in the rotors and gets flung outwards into the center iron IIRC as the engine is spinning. My assumption would be that there is some sort of internal baffling in the center iron to minimize oil sloshing and getting slung around up into the fill tube where it could be pulled into the intake (especially during shifting or braking when the throttle is suddenly closed after high speed, possibly with cornering forces when braking), but some conditions could exacerbate this and allow oil to get past the baffles. Another concern was that when refilling the oil the morning of the 2nd day, in a hurry to get out on track, I poured it in too quickly (I forgot the funnel at home) and some of that oil got into the vacuum lines etc and made it into the intake.

Either way, my thought process was that an oil catch can would tell me more about what exactly is happening. Best-case, it stays dry, no oil gets into the intake or catch can on the next track day, and the conclusion was that it happened because of filling too quickly. Worst case, oil is getting pumped into the catch can or intake due to excessive blow-by, and I've got another rotary engine rebuild in my future (I did the engine in my '88 RX-7 a couple summers ago due to a leaking coolant seal).

Loki

iTrader: (1)

Not exactly, but it doesn't really matter. There is no opportunity for windage in the oil pan, it's closed off from the moving parts. The oil you get in the intake is carried there by pressure from blow-by. Said another way, plenty of RX8s see racing and don't experience this problem, so it's a symptom.

That said it sounds like you get it. A catch can /air separator will help mitigate the immediate symptoms and you can make your plan for there.

Dodo23

I concur, my S2 had barely passing compression but it was puking oil into the intake.

toplessFC3Sman

Quick question... On my car, the line that comes off of the top of the oil fill runs down the passenger's side of the engine, into a T, and then into the two primary intake runners. Is this the same connection as the one shown in the workshop manual picture that runs to the intake manifold right after the throttle body? This seems like a very big difference in location from reality to picture, especially given the relative accuracy of the other parts.

toplessFC3Sman

Ok, I think I'm more confused now than when I started. Not only is there some inconsistency in the diagrams, but both versions (from the 2011 workshop manual, so this should be S2 specific) have only two vacuum lines going to the oil sump "tank", while my '09 seems to have 3:


I tried to overlay what I was seeing here onto the vacuum & fuel diagram from the 2011 workshop manual (same colors used), here:


The red arrow hose is the one I was referring to in the previous post, coming off of the top of the fill neck, going down the pass side of the engine, and to a "T" that then connects to vacuum nipples on the two primary runners. This one seems to start at the right place on the diagram, right near the oil fill cap, but terminates in the primary runner, similar to where "D" is pictorally shown, not in the upper intake just after the throttle body:


The green hose in the first two pictures connects the pre-throttle accordian to the oil sump "tank" underneath it, just before the tank enters the center iron (as far as I can tell without removing the oil tank and the VDI/Air Solenoid/SSV solenoid tank):


But... where does the blue hose go? It disappears underneath the oil & solenoid tanks and I can't seem to find where it pops out?

Since there was oil literally pooling in the intake accordian and air filter box after I started having this issue, the only two possibilities for oil getting there are blowby (since normal operation would have air flowing from the intake into the oil sump tank, drawn by the vacuum up near the oil cap), or some over-filling or sloppy-filling fluke since I had just added oil. Either way, this would most likely be coming through the green hose. Since the oil in the intake is cleaned up, I'm going to add the catch can on this green line and see if it reoccurs during a track day on Sunday. In the mean time, any more info on where that blue line is going, or why the red line goes so far down the primary runners would be appreciated.

Thank you!

Loki

iTrader: (1)

The line to the primary runners is your jet air, it helps fuel mix in a low speed regime, smoothes out your idle, etc. On a series 1 it's connected to the intake accordeon, and I don't think this was revised for S2. You still need jet air, and it's kind of weird to source it at the oil fill neck. Is this the original motor? Possible someone had misconnected the vacuum lines?

toplessFC3Sman

I was confused about that myself - I think this is the original engine anyway, and all the lines look like they've been there for quite some time (certainly the year & change I've owned the car)... if they arent OEM then they're very similar. Anyhow, on my engine there are two connections in the accordian (the boss for a third connection is plugged internally) - one goes to the oil tank (red line in the pictures in my last post), and the other one disappears under the oil tank (but is not connected to it), and I think curves around behind the alternator to head towards the lower intake manifold. In the picture below, I believe the line that's connected to it is the one that enters right above the coil connectors from the left of the image, then makes a 90 degree turn to head towards the LIM. I didn't trace exactly where it went, I was more focused on that blue tube in the previous post. Speaking of that one, it seems like it connects to the... I don't know? There were two of them that looked pretty similar, mounted on top of the keg itself underneath the vacuum box for the VDI/SSV/Air Solenoids...



Anyhow, I ended up getting one of the compact Mishimoto 2-port style of catch can. It had some baffling inside and a filter on the outlet, so it should hopefully do a good job of capturing the oil that enters it. The "compact" portion of the name also played into the decision, since under-hood space is pretty tight. I had to make a bracket for it to attach to, which goes between the driver's strut tower and the rear mounting point for the fuse box up in that corner of the car.



This allows the catch can to sit between the ABS pump, the fuse box, and the strut tower, and the original hose that runs from the oil tank to the accordian will even run pretty nicely to the new location, it just needs to be fished under the accordian so that it stays on the driver's side.


I tidied it up a little bit after that last picture, just to assist the new hose to run a bit more cleanly along the accordian.

Anyway, I'm still a bit confused about where some of the vacuum lines are going (especially the jet air one - that would make more sense to have going to the intake manifold than the oil...), but we'll see how things go on Sunday with this new setup.

toplessFC3Sman

Oh hey, looks like that blue line goes to one of the OMPs. I wasn't expecting to find the pumps there... i guess I was just expecting them to be low down on the pass side like they were on the 13B-T and other 80's/90's rotaries

toplessFC3Sman

Well, the catch can definitely worked - no misfires and the can collected about 2 oz of oil in each of the first two sessions. Then... Vera fixed herself? The last two sessions had no oil at all! There was definitely plenty in the sump - I started and ended the day somewhere between the full and empty marks and didn't need to add any. How strange...

Loki

iTrader: (1)

Errr, well you should be losing some oil. Mine takes about a liter per track day, which is roughly the quantity between full and low marks on the dipstick.

But good that she's not blowing more of it. Maybe the italian tune-up was needed to loosen up the seal springs Or maybe you stopped doing something you were doing before (shift points, say)

toplessFC3Sman

I tend to minimize shifting at the track so that I can focus on braking points and trying different lines, so I'll typically just leave it in 3rd gear unless the straight is long enough to require 4th. Waterford Hills (which I did yesterday) was basically all 3rd gear since I wasn't dropping into 2nd for the tighter sections, and just stayed at redline for the end of the straight instead of shifting, then needing to shift back down almost immediately. This was the same strategy I was using at Grattan two weeks ago, except the main straight was long enough that I got into 4th on it. This also seems to help fuel consumption a lot, and probably oil consumption too so the OMP is likely not injecting as much.

Now, maybe I had over-filled the oil a couple weeks ago in the rush that morning, and that's contributed? That morning I didn't do the typical "warm the engine up, shut it off, and wait 5 min" for the level to settle since I was in a hurry, but since then I have been. Following that procedure, the lower hole on the dipstick has been filled with oil when checking, while the top hole hasn't been (even if there is oil residue around it), so I assume that means the level is somewhere between the min and max lines. Anyhow, it's puzzling, but I'm keeping the catch can in place and will continue to check it when daily driving and maybe doing another track day later this year.

Shaozhou Zhang

Overfilling oil does contributes to that.
My car run does not display any symptom you said before I overfilled my oil.
After I overfilled my oil, at low load high rpm it would emit a hige cloud of blue smoke.