[quote=Highway8;3969168
He stated that prior to the catch can, under normal cruise conditions the AFR was in the 14's (closed loop) but when he goes up hills it drops to 13's (open loop).

[/quote]


The OP actually said that this condition was happening after the Oil catch can install..... Running Rich

 

Your right. His post was a little confusing and I misread.

But for what its worth. He created a vacuum leak by his install which should be causing the vehicle to run lean.

What he was oberving was normal, the drop to 13's and back to 14's is just the vehicle going from open to closed loop and back. Sometimes the stock tune does that for the Catalytic converter. What was effecting his MPG??? I dont know because if anything the vacuum leak he created might have improved MPG, not hurt it.

A better way to check if you created a vacuum leak is to watch your STFT and LTFT. If they add up to +10 or more you have a vacuum leak or a really bad tune.

 

@ Tamas

I did all three, the thought was that if the check valves fail, or stick, oil is coming up those lines until they seat. There were a few posts of the past year where people got a lot of oil, but were pretty sure they did not overfill. In that case, you HAVE to route back as opposed to run a breather. If air gets sucked out of the crankcase (or equivalent) through that tube, that air needs to be metered by the MAF.

 

Did all 3 what? You didn't run all the vacuum lines through a catch can did you?

The only place the factory placed check valves is at the OMP and the brake booster. Even without check valves, there is very little air flow, because the vacuum pressure on both sides equals each other out. If you are really worried about sucking oil into the intake tube from the OMP, just add an additional check valve. Which is what I did, when I went FI.

 

actually the best place to run a line from for a catch can is the dipstick. You still need a vacuum source , you can leave it "open" but it doesnt draw off as much condensation.
od

 

Actually I ran all three lines that feed the accordion tube through a catch can. The check valves I am referring to are the ones in the oil injector, bleeder, dripper or what ever they are and the one that is on the block that feeds the OMP. I am not sure exactly what the one on the little block does, but I did it anyway.

When the engine is running, there is a lot more flow through these lines than I though. My first round of tunes went something like "you got one heck of a vacuum leak".

I have basically the same plumbing as before, with clean, metered, air going all three places, but every potential oil source runs through the catch can. And, since I have allowed for it, I know that none of the other parts will ever fail and the can will be clean as the day I bought it for the next 100 years

 

It's still a mystery to me why a vacuum leak would show up as shifts to rich afr's in the described situation. But, within the range of the sensor, afr is afr, and 13.4 is rich right? I don't think, (though I should check sometime - the car's apart again today ...) that these slight interstate grade changes will normally cause the ECU to go into open loop, unless perhaps the fuel trims are out of range(?). In the stock configuration, afr command/actual are in rock-steady agreement.

Any ideas why the stock '06+ has essentially connected the LIM with the accordian tube?

 

Six years of of ownership and I have yet to see even the slightest justification for screwing up a perfectly good engine venting system with forum folklore fail ...

 

Two years on this forum and I've yet to see TeamRX8 contribute much of anything other than dissing other people on the forum. Multiple posts over multiple years report crapped up intake accordians and MAF sensors on the 04-05's with crapped up SSV's part of almost every discussion on rebuilds. Is this forum folklore fail? False? Unconnected with the venting system? Or don't you run into any problems running 45 seconds at a time in autox? Enlighten us with your great wisdom, oh mighty one.

 

by putting a catch can inbetween all your lines and their home like you have, does not vere from the oem design, you just added a catch can? So, in essence to me, you and Team are agreeing?
A/f's are also adjusted for load conditions. as the load increases such as when you go up a hill/incline the pcm throws more gas into the mix. This occurs with no addition throttle input from the driver. Maybe this is what is happening to the OP.

 

Probably

 

But the drop in actual a/f only shows up with the vented can in place. In stock configuration, it remains at 14.6 +- 0.1

What I'll do I think is get a can that's both sealed and has a removable top, and kluge some additional baffles inside to provide more surface area for condensation. Then splice it into the line going to the LIM and call it good.

 

Depending on your location you'd be surprised how much condensation the catch can will collect. Where I am, because of the drastic temperature change between night and day after about 2000miles I had about 1/8th of my raceroots catch can filled with water and a small amount of the white sludge we get usually on the dipstick.... when I get home from work I'll post up a pic of it drained into a clear plastic cup.

 

i take it that none of the owners who have attempted installing catch cans have read any automotive textbooks/high performance handbooks and found out how having vacuum is beneficial and even has yielded power in certain designs.

such good examples would be on the conflicting pressures between neighboring chambers...

in this department, i leave well enough alone.

 

Hey guys, ive been a 'part' of this forum for about 3 years now, I have never posted or had an account since I always found my answers by roaming and searching. Ive read multiple threads that have helped me on my journey with my RX8, so thank you all for all the countless posts on ideas and advice that have become a guide to my ownership. Heres the deal with my concern, ive been meaning to get a catch can as Mazda has put in a new engine in my car, oil has been getting into the air intake system as they dont seem to know how to properly replace the oil without overfilling it. Engine is under warrenty for a year with them and I dont really want to void it by doing it myself, I have been properly draining the excess oil but it usually takes me a couple of days to get to it. I was thinking of getting a can with a breather as I have thought of the possibility of pressure, as well as fumes being condensed in the can, but I can also see how the breather can cause the car to run lean. So my question is, best way to go without worrying about possible engine malfunction would be to just get a closed can that runs through the oil filler back to the intake? I have an 04 model btw. Sorry for the long post lol, and am sorry if its kind of a newbie question. Appreciate the read

 

Yes, put a catch can on and run hose to the oil filler neck and back to the intake. I managed to find a really good catch can, although a bit pricey it is very well fabricated at Catchcans.com.

Order the closed loop PCV style catch can.

 

Awesome! Thank you soo much for the fast reply and advice! Put in an order tonight. Thanks again

 

The first year of ownership I raced with 1 extra qt oil and still never had oil go into the intake

If an NA engine gets oil in the intake you have bigger problems than that i.e. your engine needs to be replaced or rebuilt. Attempts to slam me for posting the factual truth doesn't change it ...

 

I see, I was under the impression that if there is an overfill the Renesis will start sucking oil into the intake through the breather. Once that happens, you'll get an oil soaked*air*filter. I mean the engine is under warrenty but I havent had any issues with it other than the overfill from the dealer. but if you think that means theres a problem I can have them look into it. Appreciate the advice

 

It could be as simple as they don't use a funnel when filling. Either way a catch can will solve it, but they will see the catch can when they do the oil.

You could ask them to disconnect the hose while they fill it. To test if it's a filling problem or a engine problem.

 

Haha.... Team still bitter about a 4 year old post?

 

not me read me wrong as usual

see the post before yours; still ignorant four years later ...

 

I'm confused, the last person to mention you was in a post from 2011..... A new member has a post now asking if he should connect a vented or circulated catch can..... I don't know who is trying to slam you.


Regardless I must agree... for an FI engine it would be quite normal to see the oil in the intake without a can... Bit of a different story for NA, but again, not uncommon throughout the forum, I wouldn't say it means his brand new engine is screwed though

 

I am sincerely thankful for you guys giving me input on this matter. So the consensus overview is that having oil in the intake is not normal, regardless of the overfill? I was going to get a catch can as a 'just in case' thing since I plan on getting an AEM intake. However I will try and voice what you guys have told me to them, altho I have found myself explaining some things about the rotary to them that they themselves dont seem to get, or pretend not to

 

I personally don't care what somebody said either four years ago or today, but new members/owners have no idea what's what or also that this is as old as the RX8 itself. Ideas like pouring oil in the filler neck somehow got into the intake were all shot down a long time ago. I get aggravated that 10+ years later we're still having the same hocus-pocus reinvent the wheel baloney going on rather than learning from what has already been done and is known. So if you want to be educated about it ...

If the dealership is overfilling, is suggesting the *solution* is to buy and modify his car with non-factory approved equipment appropriate to address it? Why is he taking it to the dealer? Because he wants to keep his warranty. So that idea makes no sense. What would make more sense is for him to check his oil on the next change while still at the dealership and instead call the service manager out to see it for himself before asking them to correct the problem.

Can it be over-filled to the point it can burp. Well obviously it can if filled up completely to the top of the oil filler neck, but I know for a fact that the car will handle 1 extra qt without burping when pulling high G cornering loads. He didn't say how much it was over-filled, but for arguments sake let's say it was more than a quart. Well the service dept. is never going to pull their head out of their butt if customers modify their car to address shoddy workmanship rather than call them on it.

Why does it puke oil; generally because excessive air and/or combustion gasses are getting into the oil sump area. The air going into an engine with compression issues doesn't just vanish ...

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