Major DBW breakthrough! (I think)...
07-27-2004, 11:43 AM
#1
Major DBW breakthrough! (I think)...
Yesterday I made a post regarding a delay between the time my foot asks the car to accelerate and the time that the car actually does. This delay is about half a second long and happens only when I go from completely off throttle to any on-throttle position, regardless of whether or not the car is in gear.
Through a little R&D, I have discovered that this delay is NOT present during said maneuvers only in the two following scenarios: 1) the car is not rolling, and/or 2) the clutch pedal is depressed.
In Scenario 1, throttle response is instantaneous to allow for proper modulation during take-off from a standstill. In Scenario 2, throttle response is instantaneous to allow for (I assume) rev-matching during a downshift. In all other scenarios that I encountered, including rev-matching WITHOUT using the clutch, there is a half-second delay.
To test out my theory, I depressed the clutch pedal slightly (just enough to trip whatever sensor tells the computer the pedal is depressed, but not enough invoke clutch slip) while traveling at about 3,000rpm in 1st gear. Normally when I try to accelerate under these circumstances, I am greeted with the delay, followed by a somewhat gentle rise to full power over the course of maybe 3/4ths of a second. With the clutch pedal slightly depressed however, the acceleration was so sudden and violent that my head slammed back into the headrest and the cup of coffee I was holding (stupid of me, I know) smacked into my face. Luckily it was nearly empty so there was no mess to clean up, but just the fact that I didn't even consider setting the cup down before I tried this indicates how low my expectations were--and wow, how wrong I was! And all this with the gas pedal maybe half way down. I urge all of you with a manual transmission to try this out for yourself.
So in conclusion, I need to figure out a way to trick the computer into thinking that the clutch pedal is at least slightly depressed. I am going to look at the assembly itself to see if I can find a simple switch sensor, though I expect to find a position sensor (which can sense the position of the pedal throughout its entire range of travel) that will freak out if I unplug it. I will let you guys know what I find. In the meantime, maybe there is a way to VAG the sensor to sleep...? Any ideas?
Through a little R&D, I have discovered that this delay is NOT present during said maneuvers only in the two following scenarios: 1) the car is not rolling, and/or 2) the clutch pedal is depressed.
In Scenario 1, throttle response is instantaneous to allow for proper modulation during take-off from a standstill. In Scenario 2, throttle response is instantaneous to allow for (I assume) rev-matching during a downshift. In all other scenarios that I encountered, including rev-matching WITHOUT using the clutch, there is a half-second delay.
To test out my theory, I depressed the clutch pedal slightly (just enough to trip whatever sensor tells the computer the pedal is depressed, but not enough invoke clutch slip) while traveling at about 3,000rpm in 1st gear. Normally when I try to accelerate under these circumstances, I am greeted with the delay, followed by a somewhat gentle rise to full power over the course of maybe 3/4ths of a second. With the clutch pedal slightly depressed however, the acceleration was so sudden and violent that my head slammed back into the headrest and the cup of coffee I was holding (stupid of me, I know) smacked into my face. Luckily it was nearly empty so there was no mess to clean up, but just the fact that I didn't even consider setting the cup down before I tried this indicates how low my expectations were--and wow, how wrong I was! And all this with the gas pedal maybe half way down. I urge all of you with a manual transmission to try this out for yourself.
So in conclusion, I need to figure out a way to trick the computer into thinking that the clutch pedal is at least slightly depressed. I am going to look at the assembly itself to see if I can find a simple switch sensor, though I expect to find a position sensor (which can sense the position of the pedal throughout its entire range of travel) that will freak out if I unplug it. I will let you guys know what I find. In the meantime, maybe there is a way to VAG the sensor to sleep...? Any ideas?
07-27-2004, 12:27 PM
#2
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if the B6 are setup anything like the B5s, there should be a
clutch sensor switch towards the pivot point of the pedal under the lower dash. Not certain if depressing the clutch opens or closes the circuit. You could always splice in a toggle switch to fool the sensor w/o actually "slipping" the clutch any.
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07-27-2004, 02:06 PM
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Here
1. pry the fuse box cover off
2. undo 3 8mm bolts - 1 under the fuse box cover, 1 on each side on the bottom of the knee bolster
3. pull the knee bolster towards you - be carefull, there are wires still attached to it
4. unclip OBD connector and footwell light from the knee bolster
2. undo 3 8mm bolts - 1 under the fuse box cover, 1 on each side on the bottom of the knee bolster
3. pull the knee bolster towards you - be carefull, there are wires still attached to it
4. unclip OBD connector and footwell light from the knee bolster
