TOTALLY STUMPED!! ....can an R33 GTR be driven safely on one turbo?

[judasentinel]

Thought I'd ask this silly question, because the answer might not be that easy to find. I feel I might have blown the rear turbo. Having said that, there is no black smoke, and the car is still spooling all the way to over 1 bar. Is it still possible that the turbo is kapoot, and yet no black smoke, no hesitation under load and no weird noises under boost? Can it be driven as it is, without beating on it, until I figure this out? FUel consumption is not bad at all on the car, BTW.

This whole issue started a few months ago when I noticed the car was boosting, but there was a lot of oil coming through into the rear MAF. Someone suggested to put an oil catch can between the exhaust valve vent and the rear MAF-turbo pipe to eliminate blow-by, which I did. However, I noticed that there is no pressure being sucked into the rear turbo from the catch can.

Thereafter, I started the car, disconnected the rear MAF plug and the car continued to run. I could even rev the engine past 4000 rpm like that, with the MAF plug disconnected. And then when I reconnected the plug back on to the MAF, the car tried to stall, the revs dropped a bit and then picked up again.

Then I loosened the rear MAF from the hose going to the turbo and still, no change in the revs. I checked in the intake pipe and there was abit of oil in it...possibly either coming back from the recirc of the BOVs, or that there is a leak in the turbo compressor side. Either way, I am not sure what the issue is. I cannot tell if the wastegate is stuck open or not, or if the turbo is actually not spooling. I havent removed the intake pipe yet, and am trying to figure out if there is a way to know from the symptoms if the turbo is toast or not.

Does anyone have any ideas, or point me in the right direction as to how to troubleshoot this? The car runs great, and am wondering if one of the turbos was actually gone, wouldnt that cause leak in the boost? Also, assuming the turbo is ttoast, wouldnt the front turbo try to suck in air and then that air find its way out through the rear turbo upon revving the engine? There is air coming out of the rear MAF when I let go of the gas, and it happens with two sequential whoosh whoosh sounds from the turbo area.

Guys, I really need help here. Assuming the turbo is done, I am also in the market for a replacement R33 GTR turbo.

Thanks....sigh.....

Munib

[Cynical1]

If oil is already in your intakes by the MAF... your turbo oil seal is in need of a rebuild.

I would start by having the turbos either rebuilt or replaced before going on a different problem shooting route.

[beacher1B0]

Mechanics Stethoscope. Youll be able to hear the wheels spinning.
Your turbo is blown. Whether its spinning or not. Rebuild/Replace move on.

[judasentinel]

Thank you for the input.

If the oil is in the MAF-turbo intake pipe, it could also have been from the oil coming into it from the exhaust side vent over time, and now that I have put a catch can, the oil that found its way into the charge pipe is being recirculated back into the intake pipe from the BOVs....possible?

Is there any way to visually diagnose the rear turbo without removing all piping? I think I have ape hands, and its quite hard to reach the numerous nooks and crannies to get the turbo off. Assuming the oil seal is gone, will the turbo still be spooling/spinning? And if it is, shouldnt it be sucking in air when I rev the car? And if it is not supposed to suck in air, should I be seeing black smoke and poor fuel consumption, as the ECU registers air coming in through the two MAFs but not all of it is actually getting into the engine (therefore, the ECU dumps more fuel than is necessary)? The plugs seem to be alright, and there is very little black stuff on them.

I realize that there is also a possibility of the wastegate being stuck or damaged. How do I check that? Or is that not going to cause the symptoms I have?

[caliber676]

I don't want to sound blunt but you can't assume your turbo is blow and others shouldn't say it's done by reading a post. Oil in your intake piping before the turbo is normal, check any turbo vehicle, and skyline and whether it's a film or a fluid it'll be there with a stock pcv system. I've pulled over half a litre of oil from the intake out of a 2.0t audi engine that ran strong. Your suction from that line isn't going to be terribly strong at idle without load, as opposed to being in a high vacuum area after the throttle valves. Think of the size of the intake piping, if you put your mouth where the turbo inlet was and sucked in you wouldn't get much suction from that recirc pipe given your sucking in air from a 2-3" intake pipe as well. If your catch can is getting oil, it's doing its job. As for your maf, your car can run without a maf plugged in, it can switch to predefined mapping in the event of a sensor failure, the exact perameters for your car I'm not sure as I don't run a stock Ecu but you can check that. Honestly, it sounds like your car runs fine aside from you seeing oil and thinking it doesn't. It boosts well past stock pressure, runs fine, idles fine, and doesn't have an exhaust indication of oil burning. If you blew a turbo you would know it, it wouldn't boost to 1bar as it should and it sure as hell wouldn't idle /run right. If your wastegate is stuck open you couldn't build boost on 3 cylinders, also affecting boosting and drive ability . I would say don't worry and enjoy the car.

[Shane_Sawatzki]

^ 100% - all things aside, a blown turbo you wouldnt be running fine and boosting fine unless maybe if it was just an oil seal gone and if it was an oil seal you would be smoking like a chimney under boost.

[judasentinel]

I don't want to sound blunt but you can't assume your turbo is blow and others shouldn't say it's done by reading a post. Oil in your intake piping before the turbo is normal, check any turbo vehicle, and skyline and whether it's a film or a fluid it'll be there with a stock pcv system. I've pulled over half a litre of oil from the intake out of a 2.0t audi engine that ran strong. Your suction from that line isn't going to be terribly strong at idle without load, as opposed to being in a high vacuum area after the throttle valves. Think of the size of the intake piping, if you put your mouth where the turbo inlet was and sucked in you wouldn't get much suction from that recirc pipe given your sucking in air from a 2-3" intake pipe as well. If your catch can is getting oil, it's doing its job. As for your maf, your car can run without a maf plugged in, it can switch to predefined mapping in the event of a sensor failure, the exact perameters for your car I'm not sure as I don't run a stock Ecu but you can check that. Honestly, it sounds like your car runs fine aside from you seeing oil and thinking it doesn't. It boosts well past stock pressure, runs fine, idles fine, and doesn't have an exhaust indication of oil burning. If you blew a turbo you would know it, it wouldn't boost to 1bar as it should and it sure as hell wouldn't idle /run right. If your wastegate is stuck open you couldn't build boost on 3 cylinders, also affecting boosting and drive ability . I would say don't worry and enjoy the car.

Thank you for your encouragement. Here are the most recent facts:

The car starts and idles well. Perhaps a little bit rough when cold because the IACV might need cleaning again due to oil coming in. My boost controller shows -450 to -480 vacuum when idling. I also tried to see if the rear turbo was sucking in ANY air at all from the MAF pipe. I didnt feel any suction at all....neither at idle, nor when I revved the engine. And the catch can is not collecting any oil at all. I didnt see anything, except a little bit of moisture inside it, which could be water vapors. It did smell like oil inside it though, which I think is because of the fumes. I drove the car and it boosted right up to 1 bar without any hesitation. I drove it a bit hard for a few minutes, parked it and then check the catch can and there was no oil at all. That makes me think that perhaps the oil is not necessarily coming from the exhaust PCV.

It is quite difficult to full view the rear turbo but from what I can see, there is oil around the turbo housing, and it is not flowy and new, but more like caked on from a while ago. The turbo side of the MAF had oil on it again. It is definitely recirc air from the BOVs coming back and hitting the MAF, rather than getting sucked into the turbo as it should, so that concerns me.

As regards disconnecting the MAF plug, I think I need to repeat the experiment with the front MAF as well, to see if the car behaves the same way.

There is no blue, black or any other smoke of any kind coming out, whether at idle or while driving. And once the car has fully warmed up, it idles ok. Just to be safe, I did buy a replacement R32 GTR turbo today, in case the turbo was blown. Ou are probably right that the wastegate is not stuck open. Someone had mentioned that the car will still make 1.1 bar boost even if one turbo is not working, but with much less air. Therefore, logic dictates that the car would run stupid rich, since the twin MAF air volume has already been registered by the ECU but not all of it is finding its way into the engine if the turbo is not doing its job.

Tomorrow morning, I will try to see what the situation is like, and clean up a few things. I appreciate all the inputs, as they give me more clarity towards identifying the real problem.

Keep 'em coming....


Munib

[caliber676]

You may have an external leak from around the turbo, possibly an oil feed line. It's safe to say you would be blowing out some nasty smoke if your turbo seal was shot, after 20 years in sure there is a little residue that seeps past them on any car. You won't see oil pooling in a catch can after a few pulls, From experience you'd get a little collection after a few thousand kms in your average turbo car. Given the recirc system you can't escape oil vapour in your entire intake system. The entire intake piping will have an oil film, that's unavoidable unless you vent to atmosphere. The maf theory is a little off if I understand you correctly. If a turbo impeller/compressor wheel was gone you wouldn't have equal airflow past that mafs going through the turbo relation to the other maf so I don't think you need to pursue that theory. I'm speaking from experience here (red seal mechanic) if you aren't burning excessive oil, see a fowl exhaust smoke or have dripping or pooling oil leaks you don't have to worry about excessive and detrimental oil consumption. If your turbo is sweating oil that's something that you can look into further with dye and I cleaning and re inspection but as far as your concern of oil in the intake, you'll know when you have a real oil problem to address as opposed to normal blow by which it sounds like your experiencing. To touch on your idle concern, the iacv system on these cars are complex and cumbersome and I feel age is a more prevalent factor to its failures on almost all these cars aside from improper adjustment

[judasentinel]

Thank you once again. The above are all valuable inputs.

Here is something that I noticed on the Apexi AVCR that I have. It is that smaller, old school one. I set it to 0.65, and the car boosted to around 0.9 bar on the boost gauge. If I set the AVCR to 0.75, it boosted to over 1.1 on the gauge. I wonder why that wouyld be. I have two Greddy boost gauges, and both register the same level with a minor difference. The AVCR itself shows slightly lower pressure. Could the AVCR solenoid have caused any issues?

The car isn't burning oil. I see no puddles, no oil collecting around it, and the oil levels as checked through the dipstick seem to be adequate. I did overfill it by 1L a month or so ago, because I was concerned. No coolant oil mixing, and definitely no sputtering and smoke.

As regards the MAF theory, perhaps I should explain a bit better. After doing the pulls the day before yesterday, I removed the MAF and saw that the turbo side mesh was covered in oil. I cleaned it up, put it back on, and revved the engine to see how the car behaved. I could hear whooshing sounds from around the turbo and MAF, and saw air mixed with oil vapors escaping through the rear MAF filter when I let go of the gas. It was obvious that this was the recirc air coming back into the intake piping, but myuunderstanding was the whole purpose of recirc is to ensure that the volume of air registered at the MAF stage remains in the system and not cause rich condition/stalls upon gear shifts. This would be ensured when the recirculated air is picked up again by the turbos, thereby preventing stalling. However, I am wondering why the recirc air is only coming back through the rear MAF and why not the front as well. If there is oil that recirculated back through the BOV recirc, shouldnt both MAF intake pipes be oily? As things stand, the front MAF intake pipe is clean, no oil at all. And so is the front MAF. I have the stock recirc system, which I was told connects to both the turbos through the Y pipe in the middle. So wouldnt the oily recirc air coat both turbos fairly evenly, and not just one while leaving the front one alone? That, is what perplexes me.

I can see why this could happen though....if the two turbos are spinning at very different speeds, due to a fin or two being broken in the rear one, or for whatever reason, the wheels being resistant to free spinning. Air would find the path of least resistance and move from higher pressure to lower pressure. And if the pressure in the front turbo intake piping is higher than that in the rear turbo, the recirculated air will try to escape from the rear intake pipe. I dont know if that makes sense. Also, just tried disconnecting each MAF while the car is running. Here is what I found: rear MAF, no change in the revs, but revs drop when I try to put the plug back in. Front MAF, the revs increased when I disconnected the front MAF plug and stabilized at a higher level. And then when I put the plug back on the front MAF, they dropped to the stable idle level. So, rear MAF plug disconnected, no change. Front MAF plug disconnected, revs climb up high to maybe over 2000 rpm. What does that mean? The car didnt stall when I disconnected either of the MAFs (one at a time).

The IACV was cleaned a few months ago and a lot has happened since then. It is the whole assembly that has the idle adjustment screw on it. So I will try to clean it up if I can. I am moving and want to have her ready to be be driven while we move. Don't want to have to rent a dolly ....

I am glad that the car might be running richer than usual, but still doesnt smoke. Mornings, yes....all that moisture and burnt fuel comes out as steam, but that is normal. I remember when I broke the exhaust wheel on my turbo in my GTS-T, the cat overheated and I had the cat heating up light on. The whole passenger side floor inside the car was too hot to touch. None of that is happening.

I think I will slowly rebuild a couple of turbos with N1 parts and find an opportunity to have them replaced. All I am chasing) if I could even use that word) is a power figure of 400hwp, which I dont think I need to go to great lengths, to achieve. Stock N1 turbos, exhaust, M's filters, higher boost to 1.1 bar should bring me close to it anyway. Any shortfall in hp will be covered by the VTEC sticker I intend to slam on the trunk, hehe.....

[caliber676]

I think your plan to rebuild some turbos isn't a bad idea. Like I said I'm sure during its life the turbos on all these cars get a little tired, and seeing as though your pushing higher boost numbers and one day have a goal of some extra hp getting some new -5's or n1's would be a good investment as peace of mind maintenance and upgradeability. Get all the parts ready slowly prior to disassembly and enjoy your R in the mean time is the best method as opposed to being a jackstand racer for 5years like myself

[judasentinel]

Perhaps, I need to do what you suggested and hence, the one turbo purchase.

I would still be interested in your opinion on the two issues I mentioned, the first being oil only on the rear MAF and also the revs going higher when I disconnect the front MAF and no change when I disconnect the rear MAF.

It does idle a bit rough after doing a few pulls, but the revving is smoother. I think iot could be due to the oil getting on the rear MAF....but why not on the front MAF as well? Is that normal?

Whether I go the LS2 coil route along with N1 snail upgrade, or go single with Nistune, I do not know yet.

[Bruizer]

you have a broken horseshoe up your butt when it comes to skylines man.

if it's broken, don't drive it, might make it worse.

[caliber676]

if your running the stock recirc locations for the pcv the line runs from the left valve cover to the rear turbo, so that is the reason the rear turbo receives the blowby.

As for the mafs, again i dont know about the r33, but i know removing them sets the car into a limp mode and your revs limit out, at least in my case thats what it did. Ive heard other people unplugging them and the car dying, it really isnt a proper test, you need voltage readings and oscilloscope graphs to properly test that sort of stuff. But your symptoms arent that of a bad maf, it sounds like your hunting an idle issue more related to the iacv adjustment, possible tps adjustment.

[judasentinel]

The recirc I am talking about is not the PPCV recirc but the BOV recirc that connects to both the MAFs through the Y pipe between the two turbos/MAF intake pipes. THat's what is causing the oil to come back in this case now (since I have put a catch can for the PCV).

I need to do some more digging on the idle issue, as it is not hunting at all. The idle is stable.

[judasentinel]

you have a broken horseshoe up your butt when it comes to skylines man.

if it's broken, don't drive it, might make it worse.

Why? Because I asked a question that is dumb from a certain level of awareness? Were you born with the knowledge yourself or did you also have a time when you had to pull the horseshoe out of your butt? I guess we all have a path to walk on, and some are more far along than others...doesnt make one any less worthy of respect. Peace to you....