I have never experienced the problem myself, but it is quite well documented on the 9000 board. Many experience near stalling at idle and at any speed when letting off the gas after a boost situation. Most resolve the problem by replacing the bypass valve. A throttle body and AIC cleaning is also suggested. Townsend Imports Saab Master Site describes the bypass valve problem:

The function of the turbo bypass valve, also affectionately referred to as the "hooter" valve, because of its habit of sometimes making a hooting noise when operating, is to redirect turbo boost away from the throttle plate during deceleration. It prevents a shock wave from forming when the stream of air hits a closed throttle plate that would rebound down the induction tubing and disrupt the flow of air across the air mass meter and hit the turbo's compressor blades and stop or slow its impeller. The result of the shock wave is stalling or very low rpms when slowing down after being in a boost situation. The valve is a black plastic diaphragm with two approximately 1 inch diameter 90 degree opposed ports going into the intake tube to the turbo and the intake tube near the throttle plate (connected to the tube for the throttle plate on a 900 by a length of hose)It also has a small vacuum line on it to control its operation. When vacuum is applied to the line, the diaphragm pulls open the passage between the 90 degree ports and allows flow from in front of the throttle plate back in front of the turbo impeller effectively preventing the shock wave from forming. Often the valve's diaphragm fails, rendering it inoperative. To check the valve, apply vacuum to the vacuum line going to the valve. If you can't get vacuum to hold on the line and the line is not cracked, the valve is bad and should be replaced.

http://216.78.173.190/entry/tech_doc_systems.htm

• a list of problems, j-dog, Tue, 24 Jul 2001 16:11:55
  • Re: a list of problems, Geoff Waters, Wed, 25 Jul 2001 19:41:48
  • Try the bypass valve..., LDH, Wed, 25 Jul 2001 03:14:17
    • Re: Try the bypass valve..., Dean, Wed, 25 Jul 2001 09:17:58
      • Not so..., LDH, Wed, 25 Jul 2001 14:10:51 <-- Viewing This Message
  • Re: a list of problems, Dean, Tue, 24 Jul 2001 16:38:55
  • 'bucking', JMC, Tue, 24 Jul 2001 16:31:00

No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.

• Prev by Date: (none)
• Next by Date: Re: How to run the 12awg wire from front to back?, Dean, Wed, 25 Jul 2001 14:16:14
• Main NG900 & OG9³ Bulletin Board

StateOfNine.com

SaabClub.com

Jak Stoll Performance

M Car Covers

Ad Available

The content on this site may not be republished without permission. Copyright © 1988-2024 - The Saab Network - saabnet.com.
For usage guidelines, see the Mission & Privacy Notice.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]

Random Saabnet.com Member Gallery Photos (Click Image)