Boost noob... bad MBC perhaps?

[uberswede]

I'd kind of touched on this issue in previous threads, but now this is my main concern with the car at the moment.

I had an exhaust leak, and the car wasn't boosting well at all, but after figuring that all out, it boost great even with the ginormous turbo on it.

Anyways. In 1st gear, it only makes about 10 psi... 2nd gear, it hits around 16psi now by 6000 and stays there until red line.

These numbers are hit whether I have the boost setting on the GReddy PRofec controller set to the bottom, middle, or all the way up...

I'm fine hitting those psi's... buuuuuuut once I hit third, the boost just keeps going up, and fast. I saw it hit over 20psi before 6000rpm, and immediately let off the throttle.

I should add too that the car only had a narrow-band a/f gauge, and it doesn't tell me anything about anything... pretty sure it's pooched. I have almost everything good to go on a wide-band set up now, just have to hook it all up.


Anyways, any ideas what could be causing this seemingly never ending boost in 3rd gear?

Does it sound like it might just be a messed up boost controller? I wish I had the manual for this thing too; that would definitely help.

Could it be the wastegate? Turbonetics Deltagate Mark II

 

[talondave]

What turbo do you have? Sometimes a big turbo don't like to run at low boost levels!

 

[uberswede]

There was only a serial number on it, and after looking it up (J84A), it looks like it's some sort of Garret knockoff T70 turbo.

 

[uberswede]

Maybe I'm wrong here, but surely SOMEBODY has heard of something like this over the years??

 

[350war]

Boost creep?

 

[spyderturbo007]

I would look at your wastegate first and make sure it's not blowing open. You can check it by hooking up a compressor to the pressure source and increasing the pressure until you see the actuator arm move.

 

[uberswede]

Turns out it was the boost controller. Once I put in my AEM Tru-Boost gauge/controller, everything was so much smoother and easier to control.

HOWEVER... just today, that all went sour now. F&*(&*($Y&(*$@!!

The gauge only reads vacuum readings... and it barely reacts to the throttle... i'm guessing there's a knick/bend in the line to the gauge somewhere...

but basically, I start the car, it starts at 0, then slowly the vacuum reading moves down to -19... where it just sits. I unplugged the line going to the gauge, where it connects under the hood, and it slowly moved back to zero, but othre than that, it doesn't move around....

This gauge has been used maybe a grand total of 3-4 months, tops?


Ideas again? Haha.