Teddy952

Any ideas on how to increase vacuum in the MAF tree? Im using a Saikou Michi catch can with the top port connected to the AOS and side port connected to the MAF pipe. At cold or warm idle I have no vacuum whats so ever on the MAF port that connects to the side of the catch can. Im using 3/4" hose to connect the two and its less than a foot long. Even by increasing the RPM I still get nothing. I don't know if loading the engine will help create vacuum but that won't help at idle. This is a new build and Id assume if the block was getting vacuum I could feel it at the dipstick tube...correct?

I searched and found this to be spot on with 'smoke at idle' issues. The resolution was making sure the was enough vacuum to pull the oil through the
turbo so it will drain properly. Sounds great but the typical vacuum source in my build has no vacuum. I believe crackership mentioned using an available small vacuum line port off the intake with a one way PVC valve inline to prevent from boosting the block. Has anyone done this or see issues doing so?

thanks!

eman930

Wait so your checking for vacuum at the MAF tree? Or the oil dipstick? If your using a open catch can you will have no vaccum since its vented. Do you have pics on how your setup

Teddy952

"Wait so your checking for vacuum at the MAF tree? Or the oil dipstick?"

Both =)

I have a closed catch can. As I understand things the can needs vacuum to pull the vapors from the block. The MAF tree should be connected to the CC and provide the vacuum. Im checking the hose from the MAF tree for any vacuum and there is none at idle or by increasing the RPM. I just check the dipstick tube as an easy way to see it the block has any vacuum. Im assuming that if the block had any vacuum in it I could feel it at the dipstick tube.

I attached a picture and it shows how I have my CC setup. This is not my car but I found it from another post on RL.

black944 turbo

I don't see how it is possible not to pull vacuume at the maf tree. The engine is always in a vacuume state in front of the turbo. Have you thought about going back to stock on the aos?

Teddy952

Past posts have stated that because the MAF is less restrictive than the stock setup, it doesn't pull as much vacuum. I placed a piece of plastic bag over the hose coming out of the MAF tree. It didn't suck in or bulge out at warm/cold idle and increasing RPM gave the same results. It acted like the port was blocked off not allowing any air through. I did check just to make sure that air does pass though.

I thought about going back to the stock airbox/snorkle setup. I wanted to get opinions on using a small vacuum line directly from the intake with check valve inline. Anyone running a MAF have vacuum at the ports?

Teddy952

Forgot to add..

At warm idle I'm seeing 40Kpa at the intake manifold according to my MAP sensor.