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the ECU does not control the tranny. In fact, neither the 5-spd nor the auto tranny is electronically controlled.
What does happen in the ECU is that it limits the amount of torque produced by the engine/turbo in an auto. It does this by Pin 14 being energized in the wiring harness feeding the ECU. There's been much talk about Pin 14/Fuse 9 on the 9000 board. You can snip that wire (it's orange), or install a toggle switch to turn it on/off and keep the wire intact. This will allow the ECU to not limit the torque output, and effectively match that as what a 5-spd would have. Supposedly, Saab did this to protect the longevity of the auto, but given the fact that many of us have upgraded our cars (including me), and have not experienced any problems (in my case it's been 50K miles so far), the extra torque will not harm the tranny as long as you don't abuse it. Driving it hard is one thing, but driving it silly is another ("burn-outs", jack-rabbit starts, engaging kick-down feature at too high of an rpm, infrequent atf flush and fills, etc.).
You can't just pull Fuse 9 as it also has something to do with idle and brake boost. Also, the ECU knows it's in an auto-equipped car when the shifter is put into any forward drive gear. That's what energizes Pin 14.
Putting in a TD04 without the ECU will increase the power output over the T25, but will not put out as much as what an ECU from a TD04-equipped car would do. The ECU controls the wastegate operation and a multitude of other things to get the most out of the turbo and engine. Also, a re-mapped ECU (such as those of us have when we refer to Stage 2 or 3 or 4) puts out even more than an Aero ECU could ever do, but they're costly. There are companies out there that do this, and though I've never used one from Jak (fellow TSN'r), I have read many good things on his tuning upgrades on this site.
Just remember, once the upgrade bug bites, it bites hard and never lets up!
Joe
'98 9000CSET 115K (Stage 3 auto)
'93 900TC 156K (APC-tweaked to SPG 5-spd)
posted by 167.211.1...
, Thu, 24 May 2007 05:53:42
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