R33 GTR - oil keeps mesing up my rear MAF

[judasentinel]

I am seeing that the rear MAF is getting back flow of air when I let go of gas, and there is oil around the MAF filament. I have cleaned it up a few times but after every few days, it gets oily again. I do see that there is a hose running from the exhaust valve cover to the pipe connecting the rear turbo to the MAF, but would it be throwing so much oil into that line?

Or is it that my turbo is kapoot? Any way to check it without disconnecting everything?

I know some oil is normal in that hose, but this is a bit too much I feel.

My BOVs are recirculating back, but it seems that the recirc is not going back into the intake, through both turbos fully. Is that the reason why there would be this backdraft into the MAF from the turbo side? And why would the recirc not flow into the turbo and into the intake piping? I am totally stumped.

Ideas?

[PurpleStreak]

When my turbo oil seals blew I had oil gushing out the intakes, not in the smaller quantities you speak of however.

- Easiest way to tell if oil seals are blown is if youre making blue smoke out the exhaust
- Disconnect the crankcase vent to the intake and run for a few days and see if it improves. Hopefully you have a catch can or at least a filter to throw on the valve cover.

The recirc has to flow into the intake piping (low pressure side) and not past the compressor, otherwise it wouldnt be much of a BOV.

[judasentinel]

Thank you for the quick response.

There is no blue smoke at all. If anything, there is some black smoke as the car does run richer.

How do I block off the 1 inch pipe running from the valve cover to the intake pipe between the rear turbo and the MAF? Cap it somehow with a plumbing end and tighten with a clamp, perhaps? Any suggestion as to the kind of filter I should put on that hose coming from the exhaust valve cover?

Yes, the recirc is supposed to go between the turbo and the MAF...but I am curious as to why the air is escaping out of the MAFs and not going into the turbo compressor. Or is it supposed to be vented out through the MAF? Seems like it is not how it is supposed to be.

[judasentinel]

I think I need to explain myself a bit better. The BOVs are aftermarket, possibly Blitz, and they recirc back into the stock position (the Y pipe between the turbos). As I understand, when you let go of the gas, the excess pressure in the intake pipe is released by the BOVs either into the atmosphere, or recirculated back into the intake side of things, more specifically, before the turbos (between turbos and MAFs). The recirc air is supposed to (ideally) be pulled in by both turbos, to avoid stalling as a result of a loss of enough air to mix with the petrol being dumped into the engine, and maintain a stoich A/F ratio. Is my understanding correct?

Now here is the question: if a BOV reciculates air back into the system where it should, why would it get released through the MAF and not be sucked in by the turbos? Is that how it is supposed to be? And in my case, how come only the rear MAF is showing the air coming out of the air filter, while the front one is not?

Whenever I let go of gas, I hear two whoosh whoosh sounds one after another, even when under no load. The sound comes from around the turbos, and therefore, its not my BOVs, although they may be responsible for it. I never had this happen to any of my GTRs in the past. And after driving the car for a few minutes, and a few of these whoosh whoosh sounds and oil on to the rear MAF, the idle gets rougher.

And that is the issue I am dealing with. It has been ongoing for so long that I dont even remember how the car used to pull when I bought her in Jan. Its is still strong and goes up to 1.1 bar without a problem. But there is a lack of power that I can feel. It had new BKR7E plugs that I had put in, but they are maybe too cold for it, and unless the car was beaten up on, it would run a bit rough. I just put in BKR6Es in it with 0.8mm gap, this last weekend. And while it ran great for the first few minutes, as soon as I put load on it, and drove her around for a bit, the idle got rougher. The MAFs are fine, as I cleaned them up recently and checked the connections sinside, which are all intact.

THe coils are also all fine. I havent checked the resistance though. Which wires and how much should it be again?

Any help or a creative solution will be great.

Thanks, all.

Munib

[PurpleStreak]

You need to put a filter of the appropriate size on the valve cover nipple i.e. K&N and cap off the intake nipple. I did this first to rule out excess oil leaving this way. If you can't get a cap that size you can use a short length of hose and stuff it with a bolt wrapped in Teflon and clamp it. It only temporary

As for the turbos leaking oil, I didn't think about how it was making its way into the suction post MAF but it may be the BOVs just venting any of the oil in the charge piping. Try running the BOVs to atmosphere and see if that makes a difference

Sent from my Z30 using Tapatalk

[judasentinel]

It was easy to access the BOVs on the R32 GTRs. My car has a skidplate/underbody cover up front. DO I need to remove it all and the bumper to fully access the BOVs? Venting them to the atmosphere would also mean I have to cap off the recirc pipe, right?

I will have to go to crappy tire to find a filter for the valve cover nipple, and a bolt to cap off the intake nipple. Let's see how it goes.

[PurpleStreak]

I would think you should be able to get at the BOVs if you jsut remove the turn signal and undertray. You dont need to remove the piping completely, just disconnect and cap at both ends. Or you can just cap the recirc pipe close to the BOV and have a massive intake resonator lol.

[judasentinel]

I am thinking that perhaps I need to do both an oil catch can install and vent the BOVs to the atmosphere, and see if it makes any difference. Don't want to spend a whole lot on the catch can, so can one be made by oneself? If anyone has made one, I'd love to hear how you did it.

I removed the undertray but then underneath it is the whole skidplate/engine bottom cover as well. I did try to reach the BOVs through the turn signal hole in the bumper but my hands get stuck in there as there isnt much wiggle room in that small chamber for two hands to work and disconnect the recirc hose. I might need someone with smaller hands, hehe.