Silver Sled

I think that is the part that is causing my car to stumble since I've installed my GIAC, as I've already upgraded my DV valve with a Bailley unit.

donistook

This is a simple solenoid valve. On our race car, it caused us to loose boost....instead of running 1.4 bar, it gradually, over a three race period, dropped the boost to 1.1 bar. It is very simple to test.

We pulled it off and installed a manual boost controller.

This valve should not really cause a stumble, such as you are having.

Don Istook
ISTOOK/AINES Motorsport Group

RS

What did you do with the connector to the solenoid?

donistook

<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/Mvc-810f.jpg"></center><p>This is a boost controller off of a Porsche 935.

The stock Audi frequency valve has three ports. One goes to the breather system...that one would be blocked off. Of the other two, one comes from the turbo scroll and the other goes to the turbo wastgates. The boost controller we used is simply plumbed in between those two lines...it is simply a pressure regulator. Boost pressure comes out of the scroll fitting and is regulated to the wastgate by the regulator. The ECU now is out of the loop. The ECU will still read boost pressure and regulate injection time, ignition timing, etc.

There are electronic methods out in the marketplace that do the same thing, and probably with more consistency. We went to this while we were racing at San Diego with the Speedvision GT race and our frequency valve started leaking...in essence keeping us from running the boost we needed. A call to Audi showed that none were in the country....so we pulled the 935 valve out of our tool box and installed it. Our K04's would then produce 2.0 bar...too much...so we dialed them back to the 1.4 that we wanted to use for the race.

It is not my recommendation to have a driver cockpit adjustable boost controller such as we have....we run 100 octane fuel...the temptation is very great to just "up" the boost for normal street driving.

Don Istook
ISTOOK/AINES motorsport Group

RS

I have popped a headgasket or two, I have learned the hard way not to turn up the boost.

Did you leave the solenoid plugged in? I am worried about running too lean and check engine lights.

donistook

Yes, the valve is off of the car...it probably would trigger some light on a street car if you were to disconnect it....you could just leave the valve hooked up. I don't know why it would cause a lean condition if it was disconnected. It is just a frequency valve that cycles...the solenoid just opens and closes. The oxs sensors will tell the brain the rich/lean condition.

Don

SlvrBullet Unloaded

sounds like you may need more octane--winter gas in some places is bad!