[Digerati]

My 1994 Saab 9000 CDE FPT has been acting up sort of. A couple of months ago the butterfly valve was fixed and a new clip in place on the wastegate rod. Now, under heavy acceleration, the boost gauge only goes into the yellow andnever leaves it, even full throttle. It used to go into and out of the red w/o and problems. I realize you can shorten your WG rod, but mine is too rusty to get a turn out of it. What should I do: Buy a new wastegate, or fabricate a new Stainless Steel rod? I want my boost back...

 

[Great_Bu]

The half into the yellow will be your base boost level, normally this is adjusted by the APC (automatic performance control), the operation of which is controlled by an electronic valve situated just behind the radiator on the left (as you face forward in the car). This should have three vacuum pipes leading from it to various parts of the engine and a set of wires stuck in the back. Check that all the vacuum hoses are connected at both ends (these are the most likely to be knocked off when fiddling with the turbo) and not split and that the electical connector is still in. With this properly connected and working you should have your boost back. If it appears OK then the valve can fail internally and you can check this either by swapping it out with a known good one (if you know anyone with the same car) or by blowing in the various holes, but I can't remember where to blow/what to expect to check it's working.

 

[deevee]

The best way to test the APC valve is to unplug the electrical connector and you will see 3 pins inside the APC. You now need to test for resistance by putting a meter across pins 1 & 2 and then 2 & 3. If it is fine, you will have a resistance of about 3.2 ohms across both sets of pins. That's how I determined mine had given up the ghost.
Hope that helps
DeeVee