Oil Catch Can And Rough Idle

[GIGOLO]

Hi Everyone,

I recently Installed an oil catch can on my R33 GTS-t and have noticed that when it is not plumbed back to the intake, the car will idle rough and smell like it is runing rich.

However, when it is plumbed back into the intake the car will idle smooth. I am guessing that it is running a rich idle tune causing the car to have an almost lumpy idle.

I have tried adjusting the idle scew at the rear of the intake plenum but the problem is still there regardless of the idle RPM.

The car has a CRD tuned PFC.

Besides getting the PFC retuned (I don't have a hand controller) for the catch can does anyone have any other suggestions that may help?

[Ronin 09]

the 'smell of running rich' is the oil vapour venting out of the can

[Chris32]

Is the PCV valve blocked off? That goes from the cam cover to the plenum

if this isn't blocked of, you will have really low idle vacumm, and will cause rich running at idle/part throttle as it is sucking air back through your catch can and into your motor

either block of the PVC, or develop some sort of sealed catch can that doesn't vent to atmo

[GIGOLO]

No, the PCV has'nt been blocked off - I'll give it a go

thaks for the help

[RB30-POWER]

Is the PCV valve blocked off? That goes from the cam cover to the plenum

if this isn't blocked of, you will have really low idle vacumm, and will cause rich running at idle/part throttle as it is sucking air back through your catch can and into your motor

either block of the PVC, or develop some sort of sealed catch can that doesn't vent to atmo

<{POST_SNAPBACK}>

He hit the nail on the head for sure.

Either block the PCV or just don't run a catch can. They are only rice on 90% of motors.

[Busky2k]

Correct. The PCV pulls air through the crankcase at idle in most cars and when you put the catch can in, you've basically created a nice vacuum leak. What I do is pull the PCV out and then plumb a hose from there to the catchcan as an additional output.

[Butters]

Either block the PCV or just don't run a catch can

Amm there is also the breather into the inlet snorkle. Which fills all your piping and intercooler with oil. I'd say using a catch can to stop that isn't rice.