Velvet951

Hi, I am having a boost problem with my 89 951. It was running fine, now I seem to only get max boost at higher RPM's. I have a K27 and billet wastegate with 1 bar spring from Powerhaus. Both are only 7k old. I've checked all vacuum hoses. How do I check my BOV and turbo waterpump? What else could be wrong? The turbo sounds a little louder than normal, kind of a whoooooo sound. Also, how do I check and or remove the throttle position without screwing things up? Could my wastegate spring be broken? I am new to turbos and don't really know where to start. Thank you.

JustinL

Pull the BOV off and give it the ol' mouth to mouth. If any air leaks out when you blow into the larger tubes, you likely have a hole in the diaphragm.

Velvet951

Pull the BOV valve off where? Where would air leak out of?

pikey7

Next to/infront of the left front strut mount. Take it completely off, and blow into one of the larger tubes (there's only 3, you can't go wrong!)

Velvet951

Will a faulty BOV make the turbo sound different and or exhaust gurgle upon letup of throttle?

Velvet951

Does the BOV=cut off valve? Any other suggestions? How do I test the T-H2O pump?

Velvet951

I took the BOV(Porsche calls it a Bypass Air Valve) off and blew in the bottom and the side ports. Nothing came out the vacuum nipple when I blew in the bottom, but a little did when I blew in the side, and I had to blow pretty hard. Is this normal? Thank's everyone for your help!

blitz951

Velvet,
Check your intercooler pipes and hoses. Look all around the hose connections, make sure your clamps are tight and feel all around them to make sure there are no tears in the hoses or holes in the intercooler hard pipes from rubbing.
When the bypass valve goes bad there is usually a fluttering noise but if you do the mouth to mouth as suggested above and you can get vacum it is probably ok so I think the problem is in one of the intercooler hoses or the one the is connected to the turbo.
Your turbo water pump has nothing to do with this noise but if you want to check it just disconnect the wire off the sensor and ground it. You will then hear the pump come on.

Velvet951

I replaced the BOV, it was bad, I had the dealership check it. I still am experiencing turbo power loss. Not much happens at 1 bar, not like it use to. It is very smooth up to 2 bars, no real "punch." It accelerates ok, I can tell the turbo is doing something, just smooth, not turbo kick in. I am going nuts! Any suggestions would be most helpfup. Thanks for all the help so far!