Econmancer

This trick comes from Chris 9-5, a moderator on the SaabCentral forums. It was in a thread from July of 2007. I found it while searching for Forge diverter valve information. The OP had posted about weak turbo pressure and Chris 9-5 suggested the following modification:

Remove the top vacuum tube from the boost control valve and then plug the loose tube.

Chris 9-5 explains that it bypasses a one way valve that can become faulty.

It worked wonders for the OP. Chris 9-5 recommended that only people with weak turbo symptoms should make this modification.

As far as I knew I didn’t have any problems, the car drove as spirited as the day I purchased it. I had all the power I needed, the car was quick… so I naturally decided it wouldn’t hurt anything to try this trick.

The results were dramatic! It is like driving a different car. My whole driving experience is totally enhanced. The most noticeable change is when the transmission kicks down at wide open throttle on the highway. I really feel the torque steer for the first time, just like the OP in the thread described.

Here is how I plugged the vacuum line; I found a bolt that was the right diameter and cut it down to about an inch long. I then painted the head to make it look nicer. It’s that easy.

Some people in the thread didn’t see a difference when they removed their line. Other people tried it and found the change remarkable. The people who have made this modification haven’t seen any problems and I will make a post if I see any negative results on my 9-5. I’d say people should give this a try and see if they get back some turbo pressure. Just revert it back if there wasn’t a positive change in performance.

When I purchased my SAAB 9-5 it had 32psi in the tires. The sticker on the drivers side doorframe show three different setups with two different tire inflations. I kept it at 32psi for some time, that being the recommended tire pressure for 1-3 people in the car.

The other two recommendations, 4-5 people and 1-5 people, are both 39psi. After gas prices really started to take off in our area I decided to raise the tire pressure from 32psi to 39psi and see if that would improve my gas mileage. It did.

I went from a little more than 24mpg to almost 26mpg. Increasing the tire pressure 7psi gave me basically 1.5mpg.

There is a tradeoff for this gain. The ride is much stiffer with the increased tire pressure. It can border on uncomfortable at low speeds and I notice it the most as I roll into the garage. But a lot of people like the “stiff suspension” feel and I think it is definitely worth it for the 30 extra miles per tank of gas.

More about mpg in the SAAB 9-5:

The EPA has my 2000 2.3t with premium fuel at 18mpg city and 25mpg highway. My SID stays between 25-26mpg combined.  I drive about 40 miles every work day on the highway and 20 miles every workday in the city.

Of course, your mileage may vary.