A8 Parts Forum  

Go Back   A8 Parts Forum > A8 D2 > D2 - Transmission

D2 - Transmission Gearboxes, diffs, drive shafts.

Reply
 
Thread Tools Display Modes
  #1  
Old 13th October 2018, 10:29 AM
spannerrash spannerrash is offline
Senior Member
 
Join Date: Dec 2016
Posts: 424
Default

Hi Moltuae

Thanks for your response.

You may have something here because when I try to do a flying start from standstill, I tend to hold the car with my left foot on the break and right foot hovering over the throttle. Maybe I am hitting the throttle before releasing the break and thus maybe causing the issue you have listed above. I'll stop with the left foot breaking and see how it goes.

Thanks for your help everyone, much appreciated.
Reply With Quote
  #2  
Old 13th October 2018, 10:57 AM
moltuae's Avatar
moltuae moltuae is offline
RIP 27/02/2021 :-(
 
Join Date: Sep 2014
Location: East Lancs.
Posts: 2,679
Default

Quote:
Originally Posted by spannerrash View Post
Hi Moltuae

Thanks for your response.

You may have something here because when I try to do a flying start from standstill, I tend to hold the car with my left foot on the break and right foot hovering over the throttle. Maybe I am hitting the throttle before releasing the break and thus maybe causing the issue you have listed above. I'll stop with the left foot breaking and see how it goes.

Thanks for your help everyone, much appreciated.
I had exactly the same symptoms when I had trouble with my brake pedal switch. It would usually happen at traffic lights and, I think, more commonly following firm/heavier braking (for example, when the lights suddenly change and you decide to stop rather than go through). To diagnose it, you could try holding it on the handbrake (and dropping it in to neutral if necessary) while you're waiting for the lights to change.

There's one or two threads about the brake switch here somewhere. From memory, I believe there are two sets of contacts, one which is supposed to make/release before the other. If the timing of those contact openings/closures is not correct, it seems the ECU (the ESP ECU I assume?) limits the throttle.
__________________
Mark
------------------------------------------------------
2002 FE S8 Ebony Black Pearl
------------------------------------------------------

------------------------------------------------------
Cars Owned:
The Tesla Era: 2020 Model S Performance Ludicrous+ (present)
(Black, with all black premium interior and carbon fibre décor, 21" sonic carbon twin turbine wheels and FSD capability)

The Audi Era: '97 A8 4.2 (Ming Blue) --> '96 A8 4.2 QS (Dark Green) --> '02 FE S8 (present)
The Citroen Era: '84 BX 1.6 RS --> '89 BX 1.9 DTR Turbo --> '94 XM 2.0L Turbo --> '96 XM 2.0L Turbo Exclusive --> '00 Xantia Activa 2.0L Turbo
The Banger Era: '76 1.2L Lada VAZ-2101 (Ruski Fiat 124) --> '80 1.7L Morris Ital HL, finished in Ermine White and Rust

Last edited by moltuae; 13th October 2018 at 10:59 AM.
Reply With Quote
  #3  
Old 13th October 2018, 11:56 AM
spannerrash spannerrash is offline
Senior Member
 
Join Date: Dec 2016
Posts: 424
Default

Thanks for the info Mark.

I'll alter my driving style at the traffic lights for a while, see how that goes but ultimately will probably just buy a new switch and swap it. Already spent a fortune on the car so no point in getting cheap now.

Cheers Frank
Reply With Quote
  #4  
Old 13th October 2018, 01:59 PM
steamship's Avatar
steamship steamship is offline
Senior Member
 
Join Date: Jun 2013
Location: Londonderry, Northern Ireland
Posts: 3,238
Default

Quote:
Originally Posted by spannerrash View Post
Thanks for the info Mark.

I'll alter my driving style at the traffic lights for a while, see how that goes but ultimately will probably just buy a new switch and swap it.
If it isn't your driving style, then don't just buy a new brake switch. As Mark mentioned, the switch may just need adjusting by half a turn or so, and you use VCDS to set it.

EDIT: Just found the thread Mark was referring to. It's a pretty long one, but start from here:

http://forum.a8parts.co.uk/showpost....&postcount=285

and also check post #288.
__________________
2001 A8 D2 FL 3.7 Q - LPG Conversion, Engine: AKC, Gearbox:FBB, Colour:LY5X Aqua Blue pearl effect, Interior:WJ light beige/dark beige valcona leather with burr walnut inserts

My DIY jobs - Replaced alarm horn, Replaced Coolant Temp sensor, Updated RNS-D firmware, Installed Reversing Camera and Digital TV, Dashcam Installation, Retrofitted Rear Blinds, Auto-Dimming Rear View Mirror, Chrome Boot Struts

Sold! 2008 S8 D3 5.2 V10 - Engine: BSM, Gearbox:KLW, Colour:LY7F Suzuka Grey Pearl Effect, Interior:Black/Black with Silver/Black valcona leather with carbon atlas inserts, Bang & Olufsen, Heated windscreen, Soft-close doors, TV, DAB, AMI, Quad Zone, Auto Boot, Auto dim Mirrors, Keyless entry, PDC with rearview camera, AFS II Headlights

My DIY jobs - Fan Jet Windscreen Washers, Retrofitted Electric Side Blinds

Last edited by steamship; 13th October 2018 at 02:26 PM. Reason: Added link to relevant thread
Reply With Quote
  #5  
Old 13th October 2018, 05:44 PM
HPsauce HPsauce is offline
Senior Member
 
Join Date: Sep 2011
Location: Chilterns, almost over HS2!
Posts: 8,544
Default

It's been said above, but my very first thought was adjust the brake pedal switch.

You can monitor it with VCDS and see just how "hair trigger" the 2 separate sensors are.

I adjusted mine, but it still occasionally does the same thing. Next time I have all the gubbins out of there I'll give it another turn or two.
Sadly that will probably be fairly soon as I have an issue with my DVB-T wiring which is all buried in the same area, behind the drivers knee panel.

Basically there are two switches in one with very slight difference in the operating position. One works the brakes lights, the other informs the ECUs.
It is very possible to have the pedal released, brake light off, no braking force BUT the ECUs are still being told the brakes are on, with strange sluggish behaviour the result until some minor jolt or vibration regularises everything.
It is of course not a fault, just normal operation, so nothing gets recorded.
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant.
2016 Volvo V40 T5 Cross Country (4WD) with ALL the toys including adaptive cruise etc. etc. Osmium Grey with Blonde/Charcoal leather interior. Polestar performance "optimisation". (Even rarer than a D2 S8!) Oh, and a brand new engine at just under 30,000 miles on the factory one!
Finally: gone, but not forgotten.....
1998 D2 PF S8. Agate Grey/Platinum. Every option (I think) except electric rear seats, Tiptronic steering wheel, ski hatch, towbar & dimming door mirrors.
e.g. Cruise control, NavPlus/TV, Bose, GSM, Xenons, Solar roof, Parking sensors, Alcantara/leather everywhere of course. (internal dimming mirror added later)
1998 (very early) Ford Focus 1.8 Zetec; ABS/TCS, Heated screen/mirrors, Aircon. Added Auto-dim mirror, Leather seats, Trip computer, Cruise control, OEM Ford SatNav with CD changer.
And before that a lot of Rover 800s, a few oddities, a lovely Triumph Dolomite 1850HL with Overdrive and way back in my schooldays an Austin Seven aka Mini 850!
Reply With Quote
  #6  
Old 19th November 2018, 05:21 AM
spannerrash spannerrash is offline
Senior Member
 
Join Date: Dec 2016
Posts: 424
Default

Thanks for the response everyone.

I think we can bring this post to a close at this point.

I have altered my driving technique this last month or so and have had no further occurrences. I did purposely hit the throttle on one occasion slightly before releasing the brake and the slow acceleration was replicated.

Perhaps the brake switch may be a little sensitive and need adjusting but at the moment I'll just carry on as I am and monitor the situation.

Thanks for all your support.
__________________
Audi S8 D2 2002 88k mls
Ebony pearl effect black. Grey interior.
Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 03:24 PM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.