Erratic throttle response when cold

[MikkiJayne]

I shall be making a very similar bracket in the near future

Don't try and lever it with a screwdriver - it'll tear the plastic. You've just got to heave on it and it'll pop off the ribbed edge. Warming it up a bit is a good idea

[HPsauce]

I think I'll take the carpets up and see if I can disconnect the vertical run under there and wiggle the whole thing out. I know there's a poor/loose joint under the carpet anyway as I had to fix it with duct tape a while back. This should give me a chance to sort it out properly.

[HPsauce]

Originally Posted by HPsauce

I think I'll take the carpets up and see if I can disconnect the vertical run under there and wiggle the whole thing out.

Warmed it all up first with fan on full and ventilation on feet only. And it worked a treat once freed at floor level.
The two parts separated after a little bit of movement, then I just needed to disconnect the footwell light.

As ever, someone has been in there before as various bits are damaged (I'll fix them) including the joint between the two duct sections, but I can clearly see the target now.

Snowing a bit now so I might wait before trying any adjustments.

[HPsauce]

Originally Posted by MikkiJayne

I shall be making a very similar bracket in the near future

Don't try and lever it with a screwdriver - it'll tear the plastic. You've just got to heave on it and it'll pop off the ribbed edge. Warming it up a bit is a good idea

As it's now out of the car a close-up picture of my bracket is attached, needs a non-slip washer of some sort really where it's screwed to the plastic vent tube.

I measured the location of the fixing for the knee panel pretty carefully. It's in line with the bottom right corner of that small vent, 1.5" in front of it (i.e. towards the driver), though my bracket is fairly flexible to accommodate errors.

As for getting the joint separated I think it needs (after warming up) the horizontal section tilting towards you if at all possible to pop it open at the top left corner, given it's basically a triangular shape. I'd probably risk pushing something stiff and thin (but not sharp) in from the right, up and to the left then twisting, to force that open if I need to do it again.

[HPsauce]

Originally Posted by steamship

All I did to adjust it was disconnect it from the loom and then turn it clockwise half a turn.

I've just been to see what's involved as it's stopped snowing now.
No locking nut or anything whatsoever so I just rotated it a half-turn by hand with the wiring still connected; wasn't even difficult to get at and took only a minute!

Need to plug the laptop in now and check with VCDS, but visually the plunger still fully extends when pressing the pedal so it should be fine.

And all is well.
Not so trigger-happy now, reading changes from 1000 to 1010 on a small press, then a tiny bit more and 1011. The brake lights come on at stage 2 - 1011 so the ECU presumably knows first.

Off for a short test drive now.

[steamship]

Hopefully good news on your return.

[HPsauce]

Originally Posted by HPsauce

Off for a short test drive now.

Yes, all good, definitely driving an S8.

No glitches whatsoever, but only went a couple of miles on random roads in Friday evening traffic. Only time will tell.

I'll reassemble everything tomorrow and have a longer test run. Will probably leave the knee panel off for now as I need to get at some wiring to "improve" the rear camera installation.

[HPsauce]

Originally Posted by HPsauce

visually the plunger still fully extends when pressing the pedal

And observing that, it's a small plastic plunger pressing onto a metal bracket. There is definitely a degree of sideways movement that would rub the metal across the plastic. Given the way most people move their right foot across to the brake pedal there's almost inevitably going to be some sideways movement hence rubbing so the plunger could wear down over time.

There's probably a specification somewhere deep within Audi of what pedal movement does what to that switch, but it's certainly worth checking it next time you plug VCDS in - measuring block 66 in Engine.
I found that just hand pressure, with the engine off so no servo assistance, was enough to go through all 3 states. But you do want the pedal to have a significant movement before the switch changes.

[HPsauce]

Originally Posted by HPsauce

I'll reassemble everything tomorrow and have a longer test run. Will probably leave the knee panel off for now as I need to get at some wiring to "improve" the rear camera installation.

Reassembled, without knee panel. Getting the main horizontal duct back in was a swine of a job as it just seemed to be too long! But eventually, after connecting the inboard end first and applying a LOT of brute force, I got the outboard end plugged in with a satisfying click.
Though I'm sure some of the clicks I heard along the way were my own ribs jammed in unnatural poses halfway into the footwell.....

Test drive later, need to do it before the Rugby.

[steamship]

Originally Posted by HPsauce

Reassembled, without knee panel. Getting the main horizontal duct back in was a swine of a job as it just seemed to be too long! But eventually, after connecting the inboard end first and applying a LOT of brute force, I got the outboard end plugged in with a satisfying click.
Though I'm sure some of the clicks I heard along the way were my own ribs jammed in unnatural poses halfway into the footwell.....

Test drive later, need to do it before the Rugby.

The things we do for our cars

I replaced my TPS to try and eliminate the erratic throttle and had my head in the footwell up against the pedals, spine on door sill and on tip toes