Exhaust smoke at idle

dayhkr

Looking for suggestions and a little help, I have been searching the web and trying everything to get my 370z to stop smoking. It only does this once its warmed up, the coolant temp has to be around 200+ and the intake temp is usually 90+.

My setup:
AAM twin turbos (running on 8psi)
AAM 3in true dual exhaust
Mishimoto 3 port catch can
Ecutek tune

I originally thought it was an issue with to much crank case pressure but I have completely removed the PCV valves on the car and hooked up a Mishimoto 3 port catch can. I have 1 port going to each valve cover and the out is vented to the air. I have also tried venting directly to the air thinking that the catch can was causing issues. The car never smoked on start up I always have to drive it for a while before it starts smoking and I really only notice the smoke when I come to a complete stop. I do notices an oily film in the exhaust and also there is a small amount of film in the intercooler piping coming off the turbos. The kit isn't very old I have only had it for 6 months and the car isn't that old either only a couple of years.

Spooler

There is a thread already about this. It is an issue with the oil return on the drivers side turbo. You will need a scavenge pump to correct the issue.

Spooler

You are not the only one with a problem. It is a design issue.

Turbo oil drain problems w/AAM kit

dayhkr

Thank you for the replies it's a little irritating that AAM didnt say something when I called them.

madwi

They arent going to admit their stuff is crap.

dayhkr

Haha fair enough, I am not sure if it makes any difference but I see oil in both charge pipes. Has anyone done/documented the pump install, I will look around but any tips on where to look on the forum would help too. I am reading through the thread posted above.

dayhkr

All,

I spent all weekend looking into this issue and everyone's suggestions to see if I could find the root cause. I finally tracked down the issue to the check valves between the valve covers and the intake pipes. Apparently the shop that installed them didn't pay attention to the direction of the check valves, I noticed the arrows on the valves were pointing towards the valve covers so basically I was pressurizing the crank case. I switched these around and took it out for a drive to validate the fix. Since this change has been made I have seen no smoke from the exhaust any longer. Not sure if this will help anyone else out but its a quick fix if you run into the same issues.

Thank you for your help on this.

Martijn_b

Thanks, will pay extra attention to this ;-)

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Jayhovah

Nice find. I have read several instances over the years with people having PCV problems with the AAM kit using the valves they supply... not the first time someone has reported pressurizing the crankcase (I wonder how many oil dipsticks have been fired across shops). The part I don't really understand - my GTM/Gamma V3 just reuses the stock valve and I *think* most other FI kits do the same without problems. Why did AAM feel the need to mess with it?

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solidus

If I were OP I'd still pay attention to smoking from the turbos. If it's not doing it anymore at idle pay attention to puffs after coming off boost. I watched a YouTuber doing a feature on an AAM TT Nismo and listened to the driver say that the car smokes because he did'nt have a catch can. I just shook my head and hope that he's figured out he has an oil drain problem.

dayhkr

I have been keeping any eye on everything and had someone follow behind me to make sure there was no smoke coming out that I couldn't see. Everything is still working good with no smoking issues so in this instance I believe its the valves that were causing the problem.

dayhkr

Just a quick update for everyone the check valves did seem to solve my above problem but it only seems to have solved it when using the stock PCV system. I installed a catch can and the smoking is back, it doesn't matter if I vent directly to air or run it through the cans the smoke shows up. I am now looking into the oil drainage issue that several of you have talked about. I will probably make sure the shop that installed it didn't mess something up with the drain lines and if that looks good I will probably go the scavenge pump route.

dayhkr

Found that the passenger side turbo drain is bent a little to far and its collapsing the tube going to the oil pan. I am reruning the line so that it should drain a bit better.

Martijn_b

Another theory that ive heard, is that when not using the OEM PCV system, you dont draw a vacuum on the system as well. It might be that the kit needs the vacuum. Why not install the original PCV system back?

Fun fact: my engine was using 1qt of oil per 700 miles before turbo swap and OEM PCV system. After changing to open vent PCV i havent used oil in the 1.500 miles of boosting.

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