Help with no low end boost problem

[dhy808]

I recently purchased an '87 GN. I drove it several times after delivery and all ran fine. Hung it up for a few days to change engine, trans, and rear differential oils. When I took it out after that I had no low end boost. The boost won't kick in until the car picks up speed, then it will build boost normally. Nothing else was touched except for the fluid changes. I checked to see if I had accidentally disconnected any vacuum or electrical and didn't find anything. I went searched the forum threads and checked everything that I could find listed without success (leaking exhaust, stuck puck, disconnected vacuum hoses, etc). Other than not having low end boost/spooling the engine runs fine but no power. I tried compressing with brakes to try to build boost but none kicks in. The only way that the boost kicks in is when the car it at speed. It has a T-49 turbo, HP fuel pump and hot wire kit, 42lb injectors, CAI kit, 3" Houston down pipe, performance exhaust, and a 94 Armstrong chip. This set up was working perfectly when I received the car and I can't figure out what happened. Any suggestions will be greatly appreciated, thanks in advance.

 

[dhy808]

BTW, no scanner yet so no readings

 

[dank GN]

Well it’s hard to help you with no data that’s why a scanmaster or powerlogger is one of the first things I tell new GN owners to buy . Anyway have you tried to hook your wastegate actuator tuner style ? You basically would just run one single hose from the compressor housing to the wastegate actuator I bet if you got A manual boost controller that can be had for like $20 from eBay it would solve your issue. The cheap one works just aswell as the expensive ones FYI . I have had all different kinds. And my $20 ebay special worked just as good as my 60-70$ rjc controller.

 

[dhy808]

Thanks for the reply. I'm guessing that connecting the vacuum line directly from the actuator to the compressor bypasses the boost solenoid? If it solves the problem then the cause is a bad boost solenoid?

 

[dank GN]

Like I said I would just get a manual boost controller and I’m pretty sure you won’t have a issue like the one you are having now .

 

[NY Twin Turbo]

Take MAF intake pipe off. Grab the turbo wheel and spin it. Look at it closely. Blades are all there? Spins freely? Wire the wasgate closed. Power-brake the car. And/or take it for a ride. Keep an eye on the boost. Go easy and get READY TO LIFT if necessary.

 

[Chuck Leeper]

BTW, no scanner yet so no readings

FIRST things first....Come back w/ some data.

 

[dhy808]

dank gn, looks like you were correct. I ran the vacuum line directly from the housing to the actuator and boost is back. Does this mean that the vacuum boost solenoid went bad? I've ordered a manual boost controller and a scanner. Thanks to all for your help!

 

[TurboTGuy]

Just be sure to use all NEW rubber/silicone hosing. Zip tie all the connections.