1G Help Confirm Vacuum Routing

[carfan2000]

I was hoping someone could help confirm that my (stock) vacuum lines are routed correctly. I do have an HKS EVC plumbed in, but wanted to focus on the stock lines for now. Also, I am not quite clear on one piece of the diagram below.

In my car the Turbocharger Waste Gate Solenoid line (the white vacuum line) from the top of the solenoid is not connected to anything. In the stock configuration it is typically connected to a nipple on the Air Cleaner. However, since I have a 2g MAF and a K&N filter there isn’t a nipple to connect it to. Is it ok to let this line just dangle?

Next question, in the diagram below the black line coming from the side of the Turbocharger Waste Gate Solenoid appears to be T’ed to the Turbocharger and the Turbocharger Waste Actuator (see circled area). I thought there was only a nipple on the Turbocharger Waste Actuator, so I don’t see/understand where the line would be going on the Turbocharger. I’m assuming that I’m just misunderstanding the diagram, but would appreciate if someone could enlighten me. Thanks.

 

[TheMadCheshire]

The waste gate solenoid is designed as a bleeder valve to allow the car to boost slightly higher under perfect conditions. The computer is able to give slightly better performance(more boost) when everything is running fine. If the car is too hot, too low octane gas or other things are wrong with the car, the computer may choose to shut this solenoid and stop the leak thus leading to a lower(I do believe 7.8psi) boost pressure by sending straight pressure to the waste gate actuator. When the solenoid is open it allows the turbo to boost to 11psi(i do believe) by bleeding some of the off back into the intake and essentially lying to the waste gate actuator. Thus the need for the 'T'. To allow two paths that lead to the same destination.
But leaving the line that should go to the aircleaner unhooked, you are allowing metered air out of the system; since that line should go back into the intake. This is similar to NOT recirculating the blow of valve; metered air is allowed to escape.
You could remove the solenoid all together and make ONE vacuum line from the waste gate actuator nipple straight to the compressor nipple. This would, however, allow you to only boost to the base pressure as there is no longer a bleeder.

 

[carfan2000]

Many thanks MadCheshire… I really appreciate your detailed response.

What would be the best way to proceed if I wanted to retain the Turbocharger Waste Gate Solenoid?

Sounds like I need to T the black vacuum line from the Turbocharger Waste Gate Solenoid to both the Waste Gate Actuator and the nipple on my J-pipe (or compressor nipple as you stated). Once that is done, what can/should I do with the white vacuum line? You made it clear that it should go back into the intake, but I’m not sure how to do that without having a nipple on the Air Cleaner. Is there a common way to plumb this in, or do I have to remove the Solenoid all together? Thanks again for your help.

 

[TheMadCheshire]

The best way would have to be add a nipple to the intake that you can hook it to. The white line absolutely has to be on the suction side of the intake(pre-turbo). it seems most people who take the solenoid out usually plumb in a manual boost controller(MBC) which will eliminate the 't' and leave you with one hose from the waste gate actuator to the mbc and one from the mbc to the j-pipe nipple.
You could also plumb in a electronic boost controller the same way.

jpipe---->mbc---->wastegate actuator

 

[carfan2000]

What a difference! I removed the Waste Gate Solenoid and now have more boost. I was running little or no boost (0-3 lbs.). Now I’m making about 10lbs.

Current connections are:

Waste Gate Actuator ---> HKS EVC Control Valve Pressure Outlet Port #3
Turbo J-pipe Outlet ---> HKS EVC Control Valve Pressure Inlet Port #2
BOV ---> HKS EVC Manifold Pressure Sensor Port #1 and the Intake Manifold

Any thoughts on why I’m only able to hit about 10lbs of boost (even though I have the EVC dialed up for more)? Also, the boost seems to be coming on slow.

I’ve done several boost leak tests (at a local shop) and the only remaining leak comes from the TB seals, but it’s very small and doesn’t leak until it’s over 18lbs. Therefore, I can’t figure out why I’m still having issues with the boost. Thanks again for the help.

 

[carfan2000]

Anyone have suggestions on why I’m still experiencing low boost? Please read the post above for more details. Thanks.

 

[95redturboawd]

If you don't have a manual boost controller set up, 10 psi is normal for stock pressure.