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Thread: Hard time starting when hot

  1. #1
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    Hard time starting when hot

    Not sure how familiar any of you guys are with a6's, but mine is having a hard time starting when it gets up to operating temps. I have replaced the crack sensor and checked to see if the fuel pump is priming, which it is. There is no faults in the vag com, so I'm just a bit stomped at what i could be. Any ideas ?
    2003 RS6 Avus Silver Pearl, Apikol Side-mount IC, AutoSpeed Tune
    2001 A6 4.2 Brilliant Black, Stock

  2. #2
    Registered User hahnmgh63's Avatar
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    Fuel filter? Fuel pump pressure, check valve.
    2003 White RS6 2013 Midnight Blue S5
    2013 Daytona RS5 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
    Roy, WA

  3. #3
    Registered User kruat's Avatar
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    How old is ect sensor?
    -Mike-
    03 RS6 Mugello/Ivory #905565
    01 S4 Casa/sport/6spd

  4. #4
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    Just changed it thinking it would solve it too. But it's weird because once it startes up, it runs and pulls fine.
    2003 RS6 Avus Silver Pearl, Apikol Side-mount IC, AutoSpeed Tune
    2001 A6 4.2 Brilliant Black, Stock

  5. #5
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    Can you hear the solenoid click to push the starter gear into the flex plate?

    If so then it could be a weak battery or bad ground.

    On way to troubleshoot is to ground the engine to the body or directly to the negative battery terminal when it's acting up.
    Last edited by SteveKen; July 8th, 2015 at 02:37.
    2012 Q7 TDI S-Line - 2010 GTI - 2007 A3 3.2 S-Line - 2003 RS6
    2001 Honda S2000 - 1977 Honda CBR 750-F2 - 1965 GMC 1500 WideSide

  6. #6
    Registered User Bigglezworth's Avatar
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    Solenoid on your starter is the culprit. I'd bank my bottom dollar on it.
    '02 S6 Avant Silver - Pokey | Carbon Black/Ebony RS6 w/ stuff - darn quick | '03 Daytona Grey/Ebony RS6 w/ more stuff - quicker yet | '91 NSX CDN issue with 6spd & BBSC - quicker yet and then some | '87 Buick GNX OEM clone w/ lots of stuff - quickest hands down

  7. #7
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    Thanks for your input, I will give it a try.
    2003 RS6 Avus Silver Pearl, Apikol Side-mount IC, AutoSpeed Tune
    2001 A6 4.2 Brilliant Black, Stock

  8. #8
    Registered User Bigglezworth's Avatar
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    Also, you should first ensure you have a battery with good strength and also CLEAN connections. Heat and dirty connections create bad start problems also. Heat and a battery with a bad cell or poor charge also are a problem. I had presummed you don't have a battery problem as those are pretty straight forward to diagnose as the car turns over slowly, or lights dim as you crank, etc. I still believe you should start with the starter.... Best of success with getting to the root of the problem.
    '02 S6 Avant Silver - Pokey | Carbon Black/Ebony RS6 w/ stuff - darn quick | '03 Daytona Grey/Ebony RS6 w/ more stuff - quicker yet | '91 NSX CDN issue with 6spd & BBSC - quicker yet and then some | '87 Buick GNX OEM clone w/ lots of stuff - quickest hands down

  9. #9
    Registered User G2's Avatar
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    Yes, basically the same car sans turbo's. Typically it's going to be lack of residual fuel pressure. Sounds like Vapor Lock symptoms.
    Fuel pump check valve, fuel pressure reg. could be bypassing. Replace fuel filter if more than a couple years old.

    Last time I saw a fuel pump circuit ran off the starter or oil pressure switch was on domestics.
    Cheers, G2/Gary
    C5-RS6/KWV3/Revo/H20 Inj./Custom BBK/Custom cooling/CNC arms \ VW Touareg V10 \ B7A4 2.0T Avant \ Mk1 Callaway Scirocco \ audirs6parts@gmail.com / www.oilpro.myamsoil.com

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