96 Volvo 850 R Low Boost

[phils94850]

Im only making like 8 lbs boost maybe up to 10 at times, I have a ecu chip in the car so it should be making 15lbs. I put the chipped ecu in another car and it hit 15 so I know its not the ecu.

I pulled the vac line from my wastegate and still only getting about 8lbs boost. Shouldn't it max out on the boost with the vac line removed ? If so, then I have a issue with my wastegate ?

[jblackburn]

Torn CBV? Does it make weird sounds if you let off the gas when hard into boost?

[rspi]

I'm in the same boat. My next step is to pull the o2 sensor to see if it will boost higher (thinking that my cat is a little clogged).

I have done the following:

1. Replaced the wastegate, my old one would not hold pressure (I was over boosting).
2. Replaced the CBV (mine had holes in it).
3. Replaced all of the old vacuum lines to the turbo and intake manifold.
4. Tested it with the wastegate vacuum off.
5. Changed the BCV 3 times.
6. Replaced the seal at the base of the vacuum tree.
7. Smoked the system with a home made smoker.
8. Replaced the intake tube from MAF to turbo (mine was cracked).
9. Replaced the throttle body intake tube (the hose from the IAC had a crack in it).

My car will boost up to about 12 psi, then fall back to about 8 and hold there.

[mecheng]

What is the ambient temp? Try on a cooler night. Your car may be dialling back due to detonation. Inspect knock sensor as well.

I suggest above as it seems like your tried all the typical culprits. What tcv are you guys using?

[rspi]

I have the stock Volvo BCV installed right now. I did install a TCV out of a '98 but as explained, with the waste gate closed, the car still did not want to hold boost over 8 psi.

[scot850]

I am writing on another 850 R thread where the owner is having similar issues as am I.

Have you checked fuel pressure? The other owner found that his car was running way low which will prevent boost.

Also check emissions system for leaks.

Neil