still just me <wheeledBobNOSPAM.DeleteThis@yahoo.com> wrote:
> The Saab programming does not cause the initial problem - no boost at
> idle. That's a "feature" 
of a small turbo motor.
Then why doesn't the 9-3 -- with a *smaller* turbo motor -- suffer from
the same problem? As I said, I accidentally spun the tires when test-
driving a 9-3 because it had SO MUCH more power off the line than my
Aero. It is a slightly lighter car, but...
It took me quite a while to learn how to drive the 9-5 without nearly
killing it when starting out in 1st. I've never had that problem in ANY
other car of any size, including 3 previous turbo Saabs.
> You should understand first that your Saab engine is capable of
> producing much more HP. The turbo produces boost on a relatively fixed
> schedule depending on how fast it's spinning. The amount of boost that
> gets to the engine is determined by the opening or closing of the
> waste gate (when open, it dumps excess boost).
"Much more HP" is not what I'm worried about. Once the turbo finally
spins up, there is MORE than enough power. It's the 1.7sec or so that I
have to wait *before* the turbo spins up that bothers me. This is true
whether I'm cruising and punch it, or when I'm shifting from 1st to 2nd,
2nd to 3rd, less when shifting 3-4 or 4-5.
The reaction I get when trying to accelerate hard from a stop is:
* Ughhhh, getting it started is hard, no torque at first
* ~1.7sec later, it slams me back into the seat. The resulting surge in
speed takes me to the "time to shift" point almost instantly, so I spend
VERY little time enjoying the full power the beastie is capable of.
* Shift into 2nd, and the acceleration drops from "slam into the seat" to
"very little, what happened to my torque??" It doesn't quite jerk you
forward against the seat belt, but it almost feels like it. (Is this
because the waste gate opens when I shift, instantly dumping all boost
and spooling down the turbo?)
* ~1.7sec later, the acceleration ramps up and pushes me hard into the
seat, and once again almost instantly it's time to shift.
* Shift into 3rd, the drop in power isn't as bad as the 1st-2nd
transition but it's still significant. ~1.7sec later, etc etc.
In nearly 90k miles of driving this car, I have not found any way to
avoid this up-and-down power response when accelerating aggressively. I
simply cannot acclerate hard and smoothly. As a result I very seldom
acclerate hard. If I keep the boost gauge out of the yellow, the yo-yo
torque response is not nearly as bad. Of course, I'm only getting about
1/4 of the power and torque the car is capable of.
It's also annoying that I can't get quick response at speed. Even if I'm
cruising at 3000rpm, I get no significant torque for ~1.7sec after
hitting the gas.
BTW back in 2003 I tried a Stratmosphere Hyperboost diverter valve, which
I think is a waste gate? I saw no change whatsoever and returned it.
> ECU upgrades typically provide more HP by letting the boost build
> higher before dumping it (by controlling the waste gate). But, they
> also provide more boost *faster*, by keeping the gate closed initially
> until boost builds. The Saab factory program opens the gate quickly,
> even at low boost, to keep drivability more the way most buyers expect
> it.
Hmmm.
> There is also the MBC or Manual Boost Controller.
Now that sounds very interesting. Do you mean something like
http://smartperformance.net/product_info.php?cPath=26&products_id=34 ?
For only $25 that would be well worth trying. Do you have a particular
one you'd recommend, or is that SmartPerformance one OK?
> Back to your specific question: would an ECU (or MBC) upgrade help
> with the lag? The general answer is "yes", because it will give you
> more boost, more quickly.
That's what I want. I'll have to give the MBC a try.
Many thanks for the ****EXCELLENT**** explanation and suggestions!!!
Wish I'd known this when I started whining about it back in 2003....
Gary
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