Boost ?

[Mahonri]

Originally Posted by 89 supra

i think i got the same problem as u guys
i got a vacuum leak i dont know where yet and my car topped out at 118mph (it jumps at idle n when the cars cold i gotta give it gas so it can stay on)

it boosts normal but i only get about 4lbs of boost

could it be the vacuum leak?????
please help i dont wana end up buying a new motor

Could you be a little more specific? Are you referring to this being a Turbo issue? Or an idle issue? You said the Turbo was fine, but the idle seems to be off?

To answer the last question, it seems as though 4 lbs of boost is pretty standard for everyone with a stock setup. Although the gauge shows 8 psi being its max, 4 sounds about right. I myself have not messed with increasing the boost just yet, been fixing other small issues.

I had a vacuum leak that I took care of a couple of weeks ago. The issues I noticed were:

1. Actual spooling of the turbo was not consistent with the usual RPM range, such as spooling at 4,000 RPM and later.

2. As with any turbine, there is a distinct "whine" or high pitched noise when spooling happens, this sound was almost unheard because of the large volume of leaking air pressure, I did a simple test of this by driving close to a concrete wall to hear what was going on with the turbo.

The solution came by a simple replacement of the rubber tubing directly following the MAF sensor. As was stated earlier in this thread, that tube was cracked right at the inlet to the turbo, causing a massive leak of air pressure. But just to be safe I followed all the smaller vacuum lines to double check if anything else was getting too old and starting to crack. Lastly I checked the play with the compressor/turbine wheel to make sure it wasn't too lose, everything checked out ok.

Now the turbo spools just fine and at the right RPM's. Hope this helps diagnose your problems, any other questions just ask.