Long story short, everything is good to go now, but I'm curious as to an explanation of what exactly happened. Sorry for the TLDR thread...

Z is '05 NA non-rev up.

Earlier this year, I installed an Admin Tuning intake which does not have a port from the intake to the rear of the driver side valve cover so I needed to do something about that. I purchased a breather filter kit which places crankcase filters on the driver side valve cover towards the firewall and a breather filter on the passenger side towards the front. The passenger side breather filter came with a different valve to replace the OEM PCV valve. I plugged the port for the line leading back into the plenum on the passenger side.

Got it tuned with uprev. Everything was good to go. Fast forward to present. I figured it was not the most environmentally conscious thing to essentially delete the PCV system and vent to the atmosphere. I saw that Mishimoto designed a catch can specifically designed for the Z/G. I bought one. Installed it this weekend. It's a good kit. Everything bolts up nicely and the hoses are the correct length.

I started it up and noticed a little oil burning smoke out of the exhaust. The idle was also a little shaky and would dip down but then rev up around 1K rpm. I figured I screwed something up and possibly the kit was designed to use the OEM pcv valve.

So, I switched out the aftermarket valve with the OEM pcv valve and then started it up again. Bad idea. Immediately, oil-burning smoke started pouring out of the exhaust. Shut it down immediately. Spent the rest of the day cleaning out the plenum. Put the breather filter back on the passenger valve cover with the aftermarket valve. Fired it up. No smoke. Everything is back to "normal."

So, my powers of deductive reasoning lead me to believe that when I got it tuned earlier, it was based on the open breather setup. When I changed that, something went awry. Does this sound logical? The PCV system somewhat confuses me, so I'm just curious as to what exactly I did. Other than something bad since I'm an idiot. I guess in order to run a catch can, I would need to:

1) get it retuned and used the closed 2-port catch can,
2) run a vented single port catch can with a line from the passenger side valve cover without a retune, or
3) run a vented 2 port catch can with a breather filter and run a line from the passenger side valve cover and a line from the driver side valve cover ports without a reune.

Sorry for the long thread. Thanks for reading. I appreciate any feedback/explanations.

 

Soooo

You went from a breather on the passenger side valve cover

to a catch can and vent into your plenum and the car went haywire?

I'm thinking maybe if you want to use the catch can still you could maybe set it up and just put the breather on the can instead of into the plenum.

Maybe because the car is set up to have breathers on the valve covers instead of the cars original closed system its throwing off everything.



I am also an idiot, so take that into consideration.

 

Yeah - that's right. I'm guessing that when I got it tuned earlier this year with the open breather, it was specifically tuned for that type of setup. When I changed it to the non-vented catch can, the vacuum from the manifold started pulling a massive amount of oil into the plenum. Oh well, I'll chalk this up to a learning experience.

From what I've read on the interwebs, it seems like whenever one messes with the PCV system, the ECM may need to be changed to account for it. I guess the stock map is set up for a wide range of different factors since I didn't have any issues when I installed the breather filters before uprev.

I'm assuming the tune specifically accounted for every change I made. I think you're right that I could put the breather filter on the outlet port to essentially make it vented.

I may just get a generic 2-ported ventilated catch can if I still want to use a catch can and and run the driver and passenger side valve covers to it. Right now, everything is good to go, so I may just not mess with it anymore.

Yeah, right

 

I'm not an expert here, but back in the days of distributors you used to have a rubber hose for "vaccuum advance", meaning the timing was altered based on the amount of vaccuum in the intake. Pretty sure the same concept applies, now executed electronically.

I'd consult with your tuner and the knowledgeable folks here to come up with your final solution for hardware needs, then get reflashed under those conditions. Gl!

 

Spectre has plastic bungs, small, med & large that come together for -$10. Corresponding grommets included. I used the medium size and drilled a hole in my diy 4" pipe. Mishi catch can works well. No problems.

 

That's kind of what I figured as well. Once I get a response from my tuner, I'll post up their response in case anyone runs into the same issues in the future.

 

Thanks for posting your setup.

From your pics, it looks like you have the catch can on your passenger side valve cover from the PCV valve to the manifold without a breather filter.

Do you also have a catch can from the driver side valve cover to your intake tube? If so, how much (if any) blow by do you collect?

Also, did you get it tuned before or after the catch can install?

 

Your welcome. The driver side is attached to the intake pipe just like it was stock. I highly doubt there is any correlation regarding the catch can and a tuned ecu via software. You need to be sure air can come into the crank case and exit the crank case.

 

Heard back from the guys that tuned it and you are correct. They said that there was no specific accommodation in the tune that accounted for the open breather setup, so I guess my issue stems from user error.

When you ran your catch can, did you use the OEM PCV valve or did you drill out the internal valve or use an aftermarket fitting?

 

Initially I had a breather on the pass. side v.c. and a drilled-out pcv but I didn't like the smell inside the cabin w/the heat or a/c on and noticed the mileage went down without any noticeable power gain. Now everything is oem and the baffled c.c. is an extension of the pcv system which catches MOST of the oil. IMO I think it's good that it doesn't catch it all as some oil can get to the tops of the pistons for lubrication. Foreign cars have tight tolerances and I believe manufactures want some oil in the combustion chamber for longevity.
You must've prevented air from getting into and/or out of the crank case.