Low Boost Problem

[spyrs69]

I have an 87 GN with a TE44 (5,000 miles), 50# injectors, chip, hotwire, 340 pump, 3" downpipe, 2.5" SS ATR dual, ported throttle body, manual boost controller, KN cold air, new hoses including HD clamps, stock headers.

Several weeks ago the car only runs to 10-11 PSI. I currently have the boost set to run full. I was previously running 21-22# (not full boost setting)with mixed gas.
I have changed the header to turbo and downpipe gaskets. Also I cannot find any leaks. HELP/SUGGESTIONS greatly appreciated!!!!

 

[mybuick]

see if the vacuum line is in the right place on the wastegate solinoid. it should be on the left side and the filter on the right side... while looking at it where the vacuum lines go on to.

 

[Hammer231]

Make sure the vacuum lines going to turbo and wastegate are not reversed. This will cause low boost. Also check the wastegate flap and make sure it is lined up against the turbo exhaust housing and not allowing exhaust gases to bypass into the dp before spooling your turbo.

 

[spyrs69]

I will check on the wastegate solenoid, which is the high pressure aftermarket (stock type) adjustable one. I thought there was only one port on the solenoid but I will double check the hoses going to the turbo and solenoid when I get home. Thanks and I will keep you posted.

 

[spyrs69]

I have the rubber hose connected from the pressure source fitting of the turbo
connected to
the one hose barb on the wastegate solenoid
which then
goes to
my needle and seat, manual boost controller.

As I have driven the car, I do notice the when I begin to open the needle and seat, I am getting airflow (boost) venting out.
No matter how I adjust the needle and seat, I only get 10-11 PSI.
I also checked the plenum bolts, the aluminum vacuum port and hoses at the top of the plenum.
I am running 17-18" vacuum at idle and the car runs fine, without any apparent vacuum leaks.
I also checked the headers while the engine is running and I don't detect any exhaust leaks prior to the turbo.
HELP!

 

[SHADOWII]

Try eliminating the wastegate solenoid. I completely removed mine and I run 26#s I have the Q-boost w/ incar adjuster.

 

[spyrs69]

Good call ShadowII. Bypassing the wastegate solenoid resulted in the car going into full boost. Now I just need to find an alternate wastegate controller/actuator. Thanks.

 

[acoen]

Reading your post, my car is factory stock and I have a similar problem. Will a faulty wastegate solenoid cause the car to run a low boost pressure. I'm getting around 10-12psi.

 

[spyrs69]

You could try what I did, which was plug the boost source at the turbo, bypassed/eliminating your wastegate solenoid. Carefully what your boost gauge and see if the boost goes above 12psi.