8th October 2004, 01:04 AM
I have been told that removal the 1st/2nd gear torque limiter on the B235R T7 (Viggen, 9-5 Aero) can be done via the ecu by some of the ecu tuners. I've been thinking it can't be the only way as there must be some signal (most likely in the tranny) telling the ecu what gear is engaged so it knows when its in 1st or 2nd. Does any one know if true and if so where this senor is specifically located and what the electical schematics for it look like? What I'm thinking is that if there is some sensor sending and electical or ground signal to the ecu when in 1st or 2nd that you could just wire up a switch that when its engaged the ecu would think its perminitally in 3rd, 4th and 5th....allowing to disengage the torque limiting feature when you wanted to (like when you wanted to really launch off the line).
If I'm way off with this can someone explain to me how the T7 ecu know when the car is in 1st/2nd?
8th October 2004, 02:38 AM
Checked the WIS ... the car uses the wheel speed sensors and RPM to determine the gear ratio.
18th October 2004, 02:12 PM
In other words, the limitation is "bits and bytes" can not be taken away just by cutting a wire.
9th November 2004, 08:10 AM
A further thought on this, perhaps Dr Boost can confirm if this is so?
When the ecu compares wheelspeed with rpm it is able to calculate which ratio the gearbox is in. There is presumably an accepted range of rpm for any given roadspeed and any given gear. If the ecu uses the wheelspeed (roadspeed sensor) on the rear axle and the front wheels are spinning, is it possible that the ecu will calculate that the car is in a lower gear than it actually is? If the car was actually in third, but spinning to indicate a calculated second, the engine torque will be cut back (limited-even though the car is in third) which will tend to reduce the wheelspin.
TCS of a kind even with the TCS turned off????
18th January 2014, 07:49 PM
4 speed automatic only have first gear torque limiter?
19th January 2014, 10:04 PM
If the ecu uses the wheelspeed (roadspeed sensor) on the rear axle and the front wheels are spinning, is it possible that the ecu will calculate that the car is in a lower gear than it actually is?
I'm betting the ECU programming is smarter than that. It may use the rear wheel sensors for roadspeed during tirespin, but the ratio between engine speed and the average of front wheel speed sensors will always be the trans ratio unless the clutch is slipping. The ecu is still seeing the front wheel speed during wheelspin and can still make that calculation.