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#1
27th April 2011, 08:18 AM
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Engine not starting
My S8 has just started to play up again. The other day while driving on gas it struggled to rev, then the car light came on.
I turned of the engine and it failed to start on petrol, it stalls right away and its not possible to build any revs. It started on gas and drove ok but now it wont do either. If i try it on fuel it stalls immediately and bearly starts, if i try it on gas it sometimes works and then stalls after a few seconds. Its usually fine starting on gas if I need to so there is defiantly something wrong. I have checked fuel pressure which is flowing. Im in the middle of no where in france at the moment and dont have access to an error code reader. I have ruled out the ISV and the TB as its not even staying on if you try to open the throttle. Does anyone know what this could be? Maybe the MAF? or the lambdas? Please help if you can, Cheers. Bo 
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#2
27th April 2011, 08:32 AM
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It's possible that it is your immobiliser. Do you have another key?
__________________
Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light. 
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#3
27th April 2011, 10:40 AM
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Sounds like the immobiliser, I get this intermittently too. If that light on the dash is flashing then it will not start, well it will but shut off.
Try taking the key out, put it back in turn the ignition on and see if the light goes out and stays out, if not try again. Can be a pain at the petrol station.
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#4
27th April 2011, 01:27 PM
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I just checked the light, it goes out about 1 second after the ignition is turned on.
Can someone confirm that its not MAF or Lambda related. Thanks for your help guys. Cheers. Bo Last edited by s2_bo; 27th April 2011 at 01:30 PM.
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#5
27th April 2011, 01:32 PM
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Faulty mafs and lambdas at worst would make it run lumpy, or cause the engine warning light to come on. I cant see it would cause the issues you describe....
I would suspect the immobiliser if it was purely a starting issue, but it sounds like it died whilst running fine ?, which would rule it out. If both fuels produce similar results, you can rule out fuel supply, which leaves really coils / plugs / timing / wiring Is it smooth when it runs for a second or two, or a bit lumpy ?
__________________
For parts enquiries and Forum User Administration please contact customer services directly, not me  - enquiry@a8parts.co.uk, www.a8parts.co.uk, or call 01642 783537The Daily Town Car - 2023 Tesla Model Y Performance. Black with Black. Giant ipad screen, huge sunroof, 4 wheel drive, Tow bar, lots of ooomph and made in China, so actually built properly unlike the Californian ones. The Family Wagon - 2018 Tesla Model X. Black, 7 Seats, Towbar, Homelink, Enhanced Auto pilot with Summon and self park, Heated front seats, CCS Charger upgrade, MCU2 Upgrade, Falconwing Doors, Self opening / closing doors, Netflix, Spotify, toys, Air suspension, alcantara roof + lots of other stuff...... The 17 year old Driver Wagon 2015 Skoda Citigo Monte Carlo. Alloys, Power steering, Aircon, Leccy windows, Sat Nav, bluetooth, central locking, cup holders, 59 whole bhp. Million times better than my first car. Well jealous..... The First 20 Audis: 2001 D2 4.2 QS Silver, 1997 D2 S8 Silver, 1999 D2 4.2 Silver, 2002 D2 S8 Dolphin Grey, 2003 C5 RS6 Blue, 1998 D2 S8 Black, 2000 D2 4.2 QS/S8 Ming Blue, 2003 D3 4.2 Ming Blue, 2005 B7 S4 Blue, 2006 D3 3.0 Tdi Black, 1999 D2 4.2 Silver, 2003 D3 4.2 LPG Crystal Blue, 2000 D2 S8 Silver, 2007 3.0 Tdi Q7 Black, 2009 B8 S4 Black, 1998 D2 S8 Agate Grey, 2006 D3 4.2 Tdi Blue, 2006 D3 S8, 2007 Q7 3.0 Tdi, 2006 C6 S6, The Second 20 Audis: 2011 A7 Sline, 2001 A2 1.4 Tdi Black, 2002 A2 1.4 Tdi Silver, 2006 A8 4.2 Tdi Blue, 2007 4.2 Tdi Q7, 2006 S4 Cab Silver, 2010 RS6 Saloon Black  , 2007 TT Roadster, 2010 A8 D4 4.2 Silver, 2006 C6 A6 2.7 Tdi Quattro, 2000 D2 4.2 QS/S8 Ming Blue (again), 2008 Q7 4.2 Black, 2009 C6 RS6 Saloon Daytona Grey, 2001 Fully Loaded A2 Tdi, 2006 Avant S6 Black, 2007 VW Caravelle Exec Black (almost an Audi) 2009 TT Roadster Daytona, 2015 Q7 4.2 tdi lava grey, 2002 GmbH D2 demonstrator, 2006 D3 A8 LWB 4.2 Tdi Black Most Recent Audis: 2001 A2 1.4 Tdi Black, 2007 4.2 FSi Q7 ABT Blue, 2016 S5 Coupe Launch model, 2004 S4 B6 Cabriolet, 2016 Q7 Sline White, 2006 Q7 4.2 FSi Black, 2012 Q7 Sline+ 4.2Tdi White, 2008 Blue Audi S8 Everything Else 1989 Subaru Justy, 1986 Vauxhall Cartlton 2.0 GL, 1985 Vauxhall Carlton 2.2 CDi, 1987 Ford Sierra XR4x4, 1983 Vauxhall Senator, 1985 Vauxhall Senator 3.0i, 1997 Polo Saloon, 1997 Peugeot 306 1.9 TDi, Ford Sierra Sapphire 2000E, 1990 Subaru Justy, 2000 Subaru Impreza, 2000 Subaru Impreza RB5, 1993 Range Rover LSE, 2005 VW Bora, 2003 Skoda Superb, 2003 VW Passat V6 4 Motion, 1996 Peugeot 106, 2000 Range Rover 4.0, 2019 Tesla Model 3 Performance
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#6
27th April 2011, 01:38 PM
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Quote:
Its pretty smooth although i have now tried it about 20 times and sometimes it also sounds like its not firing on a few cylinders when it starts up. it sounds like tis really struggling to start. I would suspect if it was the imob it would fire up fine and then stall, which is not the case. Very bizarre. Earlier it did start on gas and i managed to get the revs up before it died. I held it at 3k for about 20 seconds then off throttle and it stalled right away.. While it was running it sounded fine but made no attempt to idle. Ill check the breather hoses maybe one has perished and is coursing unmetered air to come in. Last edited by s2_bo; 27th April 2011 at 01:40 PM.
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#7
27th April 2011, 02:35 PM
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Im presuming fuel should flow in at the pipe which does not have the FPR attached to it?
If i crack the FPR one off its dry.... Also when cracking off the other fuel line it spits as the nut is undone, so there must be air in the fuel rails. Maybe my fuel gauge is lying, (says its half full) and when i cranked it over to check fuel pressure it was only spitting out..... Anyway, i have sent someone out to get 30l of 98ron so ill see what happens hen that goes in. I think its poss that a cold start on gas can be unsuccessful as the liquid gas can freeze the vaporizer.. If all the above are right then thats hopefully the only problem... Will update later if i get it to work. Thanks again for your time.. Bo
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#8
27th April 2011, 02:37 PM
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Could well be, its not uncommon for problems in the fuel tank to stop the bottom half of the tank being drawn off, ie when gauge says half full, it is, but it cant get to it, so might as well be empty.. !
__________________
For parts enquiries and Forum User Administration please contact customer services directly, not me - enquiry@a8parts.co.uk, www.a8parts.co.uk, or call 01642 783537The Daily Town Car - 2023 Tesla Model Y Performance. Black with Black. Giant ipad screen, huge sunroof, 4 wheel drive, Tow bar, lots of ooomph and made in China, so actually built properly unlike the Californian ones. The Family Wagon - 2018 Tesla Model X. Black, 7 Seats, Towbar, Homelink, Enhanced Auto pilot with Summon and self park, Heated front seats, CCS Charger upgrade, MCU2 Upgrade, Falconwing Doors, Self opening / closing doors, Netflix, Spotify, toys, Air suspension, alcantara roof + lots of other stuff...... The 17 year old Driver Wagon 2015 Skoda Citigo Monte Carlo. Alloys, Power steering, Aircon, Leccy windows, Sat Nav, bluetooth, central locking, cup holders, 59 whole bhp. Million times better than my first car. Well jealous..... The First 20 Audis: 2001 D2 4.2 QS Silver, 1997 D2 S8 Silver, 1999 D2 4.2 Silver, 2002 D2 S8 Dolphin Grey, 2003 C5 RS6 Blue, 1998 D2 S8 Black, 2000 D2 4.2 QS/S8 Ming Blue, 2003 D3 4.2 Ming Blue, 2005 B7 S4 Blue, 2006 D3 3.0 Tdi Black, 1999 D2 4.2 Silver, 2003 D3 4.2 LPG Crystal Blue, 2000 D2 S8 Silver, 2007 3.0 Tdi Q7 Black, 2009 B8 S4 Black, 1998 D2 S8 Agate Grey, 2006 D3 4.2 Tdi Blue, 2006 D3 S8, 2007 Q7 3.0 Tdi, 2006 C6 S6, The Second 20 Audis: 2011 A7 Sline, 2001 A2 1.4 Tdi Black, 2002 A2 1.4 Tdi Silver, 2006 A8 4.2 Tdi Blue, 2007 4.2 Tdi Q7, 2006 S4 Cab Silver, 2010 RS6 Saloon Black , 2007 TT Roadster, 2010 A8 D4 4.2 Silver, 2006 C6 A6 2.7 Tdi Quattro, 2000 D2 4.2 QS/S8 Ming Blue (again), 2008 Q7 4.2 Black, 2009 C6 RS6 Saloon Daytona Grey, 2001 Fully Loaded A2 Tdi, 2006 Avant S6 Black, 2007 VW Caravelle Exec Black (almost an Audi) 2009 TT Roadster Daytona, 2015 Q7 4.2 tdi lava grey, 2002 GmbH D2 demonstrator, 2006 D3 A8 LWB 4.2 Tdi Black Most Recent Audis: 2001 A2 1.4 Tdi Black, 2007 4.2 FSi Q7 ABT Blue, 2016 S5 Coupe Launch model, 2004 S4 B6 Cabriolet, 2016 Q7 Sline White, 2006 Q7 4.2 FSi Black, 2012 Q7 Sline+ 4.2Tdi White, 2008 Blue Audi S8 Everything Else 1989 Subaru Justy, 1986 Vauxhall Cartlton 2.0 GL, 1985 Vauxhall Carlton 2.2 CDi, 1987 Ford Sierra XR4x4, 1983 Vauxhall Senator, 1985 Vauxhall Senator 3.0i, 1997 Polo Saloon, 1997 Peugeot 306 1.9 TDi, Ford Sierra Sapphire 2000E, 1990 Subaru Justy, 2000 Subaru Impreza, 2000 Subaru Impreza RB5, 1993 Range Rover LSE, 2005 VW Bora, 2003 Skoda Superb, 2003 VW Passat V6 4 Motion, 1996 Peugeot 106, 2000 Range Rover 4.0, 2019 Tesla Model 3 Performance
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#9
27th April 2011, 06:53 PM
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That was it!
Put in 30l and it started second time and runs as normal. Gauge now reads 4/5 full... Thanks for your help gents, ill keep this in mind and will keep both tanks brimmed.. When i removed the tank on my other S8, I put 12v to the pump in situ and ran it till the pump was sucking air. After i removed the tank it still had 12L in it! Seams to be quite a complicated system inside the tank as it has thoes two legs. Maybe one of the internal feed pipes on mine is blocked... Anyway, I'm happy that its working again now! Last edited by s2_bo; 27th April 2011 at 06:59 PM.
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#10
27th April 2011, 08:01 PM
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The system is complex!
 I've played around in the tank when replacing a fuel pump.The pump sits in a sump of fuel and it is above the level of fuel at less than a quarter of a tank. However, fuel remains in the sump-part of the pump assembly which allows the pump to prime. When in operation the pump drives fuel into the tank to either side to drive 2 turbines that send fuel to the fuel rail. That way each side is being fed fuel so they stay the same level With me so far? The low pressure return from the fuel rail goes up to the header tank at the fuel cap and cascades back down into the sump that primes the pump. If the sump dries out then the pump wont prime. Simples! 
__________________
Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light.
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