Inconsistent acceleration - Saab content

So I've been driving my newly acquired '01 Saab 9-5 wagon for several weeks. It's the 2.3L w/5spd. Absolutely love the car, great for dd use. I have noticed one odd thing with it, and I don't have a lot of experience with turbo motors.

Sometimes when I'm on the gas, the acceleration is best described as "inconsistent". I'll feel the turbo in one gear and see the boost gauge go up, but when I shift into the next gear, the car falls flat and I get little or no acceleration. The car isn't running rough, I don't hear any misfires from inside the car. Just have no juice. If it happens when I shift from 4th to 5th, I sometimes have to go back down to 4th for a few seconds before going back into 5th, because the car just won't go. The turbo is nearly new, was replaced with a new OEM 10k miles ago (I've got the dealer service dept receipt). Only code the car has thrown is due to a slow to respond cat. It's really strange. It's not consistent in that it only happens in certain gears. Sometimes it doesn't happen at all, sometimes it does, different gears (though usually not in 1st). Any idea what's up?

Does it always have boost the first time you run it hard, but in the next gear, it might not?

I'll have to try to do a hard run through the gears. I typically drive it fairly easy on the gas...trying to squeak out fuel mileage. Even so, I still feel the boost most of the time. But then once in a while I'll grab the next gear and the engine falls on its' face...when that happens, even if I floor it I still get almost nothing.

The reason i ask is that it almost sounds like an issue with the wastegate.

Are the RPMs going up in 5th when you're not accelerating? Your symptoms almost sound like a clutch that's starting to slip. 5th gear is one of the first places you'd pick up on that.

Sounds like a bad/sticky wastegate actuator. Your hooter valve might be blown out too (good excuse to replace with a piston unit), or your BPC valve might need a good cleaning. Saab T7 relies on a lot of feedback to control boost, so make sure all your sensors are good and your vacuum lines are solid.

or if you are referring to not building as much boost in certain gears as others, welcome to GM era boost cuts. My '05 Ion Redline(saab ecotec 2.0L, but with m62 s/c), had different boost levels for each gear aside from 2nd and 3rd. Plugging the boost bypass actuator gave a consistant 15.5lbs in all 5 gears.

yamaha wrote: or if you are referring to not building as much boost in certain gears as others, welcome to GM era boost cuts. My '05 Ion Redline(saab ecotec 2.0L, but with m62 s/c), had different boost levels for each gear aside from 2nd and 3rd. Plugging the boost bypass actuator gave a consistant 15.5lbs in all 5 gears.

You have to be careful doing that on turbo Saabs, if you do it wrong you effectively lock the wastegate closed - some guys have toasted their motors that way.

I don't think it's the clutch slipping. When the issue happens, the rpms don't build at all. They stay steady, the car just won't accelerate well (or at all if in 5th gear going up hill). Hooter valve? BPC valve? Got lots to learn about these things... I'll check the vacuum lines for any obvious leaks. How do I check to see if the sensors are good?

Klayfish wrote: How do I check to see if the sensors are good?

Like any other car, grab your meter and test for proper resistance spec on each sensor, or just replace them. O2, intake air temp, air mass, coolant temp, etc all contribute to T7's control. The SaabCentral forums are probably the best 9-5 board on the net, they have the info you need. Bypassing the throttle delay valve might help too.

SlickDizzy wrote:

yamaha wrote: or if you are referring to not building as much boost in certain gears as others, welcome to GM era boost cuts. My '05 Ion Redline(saab ecotec 2.0L, but with m62 s/c), had different boost levels for each gear aside from 2nd and 3rd. Plugging the boost bypass actuator gave a consistant 15.5lbs in all 5 gears.

You have to be careful doing that on turbo Saabs, if you do it wrong you effectively lock the wastegate closed - some guys have toasted their motors that way.

Yes you have to be careful, but I meant only to explain the fact GM does stupid things with boost control

Had similar oddity with my 9-5 stick wagon (miss that car) but also came with a CEL. It was improper vacuum line routing following a water pump change. Could be bad boost controller, there is an easy check you can find on the Saab forums - use a golf tee to bypass the unit. If problem goes away, bad boost controller. They are easy to source used. But my guess is vacuum problem somewhere - misrouted lines can be hard to spot unless you know where everyting is supposed to go. A Saab specialist sorted it for me easily.

On my 9000s, the boost control solenoid (small thing mounted to the radiator with three hoses and two wires going to it), would get sticky and boost would do weird things. Taking it off, soaking it internally with brake/carb cleaner and or seafoam always made it work again. If the solenoid inside gets hung up, it won't move to control the boost properly. It's easy and cheap to try.