low boost problem
 

I have done lots of searching here and on rennlist but need some help. Car is and 87 951 and has a low boost issue. It makes about 8psi max. Motor is stock.

Idle vacuum is about 16hg
Deccel vacuum is about 21-23hg
When I clamp the line to the wastgate I get 12 psi max.
BOV holds vacuum.


My searching tells me my wastegate is okay, is that right?

Where should I look next? Besides a cold motor stumble/hesitation the motor runs well (other than the lowish boost numbers). I have replaced a majority of the vacuum lines and tested the intake manifold gaskets for leaks.

Thanks for any insight....

Cheers

Check the 3 rubber hoses downstream of compressor. There are two at the intercooler (pre and post) and one large one where the compressed air leaves the compressor. Remove the one at the compressor to have a good look at it.

There is also a rubber section right at the throttle body but I've never seen one of these split.

Thanks, I will be looking there next! Is there commonly available silicone replacements for these couplers, or is factory original the way to go if they need to be replaced?

Cheers

Re: low boost problem
 

http://www.clarks-garage.com/shop-manual/exh-02.htm
um your waist gate is bad. when you clamp the line to the waist gate it should send your boost to over 20psi. i would look at the waste-gate. as for the cold motor hesitation /stumble let your car warm up for a couple of min before driving

My cat. conv. truned out to be the culpret when I had low boost issues. It was nearly clogged as the PO ran low octane fuel and had a bad O2 sensor. Installed a cat bypass and went from 8 to 12 psi boost. Huge difference.

Thanks guys!

Cheers

how do you know what psi you are getting? do you have an aftermarket gauge ?

Aftermarket gauge installed in the car, I think the WG is pooched, I have a spare one now and will put it in and see if this solves the problem. I have to do a water pump and belt service first so it will be a few days, but I will report back with my findings!

Thanks to all who offered up some help :)
Cheers