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  1. #1
    Senior Member Four Rings Theiceman's Avatar
    Join Date
    Feb 15 2016
    AZ Member #
    368804
    Location
    Cambridge Ontario

    I may have set a reliability record !

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    Unfortunately the wrong kind.
    Went to pick up new to me car today 80 miles away. ? (219km on it so a high miler )

    Got in and saw engine light on ( hmm wasnt on during test drive ) underboost 299. Didnt even have to look it up. Lol.
    No big deal, reset it, i bought the car to tinker as thats my thing and ive never done a turbo issue.
    Got in drove it 80 miles. Pulled like a freight train. This turbo does NOT have boost issues so maybe a minor leak somewhere. ( code for this has not come back so far )
    Anyway. Gas light comes on about 20 miles out from home but shows lots left. ( just under 1/4 )
    Decided to go to the car wash on the way home. In the middle if the car wash ! Epc light comes on service due light comes on. Check engine light comes on car dies in the freakin car wash. !!! Absolutely would not restart. Never even got it home.
    My son pulls the code, fuel pressure regulator out of spec.
    So we push it out. My son instantly on the web finds a thread with my EXACT issue. Sitting at idle, same lights on, hot day ( 30c) low fuel.
    Recommendation is leave it 10 minutes. As its vapour lock. Should not let car get bellow 1/4. Sure enough. Wait half an hour while we cleaned the inside.
    Car fires up and idles perfect. We drive 10 minutes to gas station and fill it up ( there was 9 litres left in it ) . No issues all of last night during 20 mile shake down.
    Sooooo........
    Definitely sounds like vapour lock and i appreciated the info to get going , but not letting get below 1/4. ? Thats. BS.
    Any thoughts on tank evap valve causing this?
    No evap or other stored codes at all.
    Guess it could be lpfp or hpfp. I thought follower was fixed on this with roller style.
    Any comments or advice ? Dive into it or let it roll for now ? Any common parts that might cause this ?
    Btw car idles when warm about 700rpm. Which seems low to me and being that low a tiny bit shaky. . May need carbon clean at that milage.
    Appreciate any thoughts.

    Oops required pic. IMG_7541.JPG
    Last edited by Theiceman; 09-18-2018 at 12:00 PM.
    2014 Nissan Murano
    2006 A4 2.0TQ 6spd
    1978 Porsche 911SC Targa
    1976 Yamaha XS 360

  2. #2
    Established Member Two Rings alhutch's Avatar
    Join Date
    Jun 03 2017
    AZ Member #
    400524
    Location
    Portland, OR

    The in-tank pump is cooled by fuel, so when fuel is low (<1/4 tank) on a hot day, it is not getting cooled enough. Throw in the miles/age (136k) and maybe it just isn't as efficient as it should be when warm and providing lower pressure than desired to the HPFP?

    I replaced the in-tank pump on wife's MK4 GTI (1.8T) for that reason. It started sounding weak on door open (pump primes when driver's door is opened) and it was showing some hesitation on WOT at times. Replaced the pump (car was 15 years old at the time, but only 85k miles) and all was right again. She liked to drive around with low fuel too (never filled before the light and usually waited a day or two after it came on). We don't do that anymore.

    Carbon cleaning needed for sure by that mileage too.
    2013 Allroad - Volcano Red

  3. #3
    Senior Member Four Rings Theiceman's Avatar
    Join Date
    Feb 15 2016
    AZ Member #
    368804
    Location
    Cambridge Ontario

    I do realize i was in a car wash so could have even been water intrusion. But im considering that unlikely at this point


    Sent from my iPhone using Audizine
    2014 Nissan Murano
    2006 A4 2.0TQ 6spd
    1978 Porsche 911SC Targa
    1976 Yamaha XS 360

  4. #4
    Senior Member Four Rings Theiceman's Avatar
    Join Date
    Feb 15 2016
    AZ Member #
    368804
    Location
    Cambridge Ontario

    Quote Originally Posted by alhutch View Post
    The in-tank pump is cooled by fuel, so when fuel is low (<1/4 tank) on a hot day, it is not getting cooled enough. Throw in the miles/age (136k) and maybe it just isn't as efficient as it should be when warm and providing lower pressure than desired to the HPFP?

    I replaced the in-tank pump on wife's MK4 GTI (1.8T) for that reason. It started sounding weak on door open (pump primes when driver's door is opened) and it was showing some hesitation on WOT at times. Replaced the pump (car was 15 years old at the time, but only 85k miles) and all was right again. She liked to drive around with low fuel too (never filled before the light and usually waited a day or two after it came on). We don't do that anymore.

    Carbon cleaning needed for sure by that mileage too.
    Yeah i agree with the possible pump issue. But if anyone from Audi told me id have to keep it over 1/4 full we would be having a discussion.
    Probably would not sell many cars in Southern cal, Texas, or Florida if that was the case.
    Probably not a bad idea to throw in a pump as PM at this milage.
    Ran fine today all day but the car is thirsty !! Could be me lead foot though.


    Sent from my iPhone using Audizine
    2014 Nissan Murano
    2006 A4 2.0TQ 6spd
    1978 Porsche 911SC Targa
    1976 Yamaha XS 360

  5. #5
    Active Member Three Rings
    Join Date
    Jun 17 2018
    AZ Member #
    420830
    Location
    Colorado

    So maybe start off by running a tank of BG44K to try to clean anything out that might be in the fuel system?

    Just an idea. Not sure what's going on here... what are the other codes it's showing? If it is low on fuel pressure, it's pretty good at telling you where - whether it's high pressure, lower pressure side, etc.

    - - - Updated - - -

    Also, I guess this is your proper welcome to B8 ownership! At least I had the same welcome. In my case it was an injector failing ~1.5 after first getting after it.

  6. #6
    Active Member Three Rings
    Join Date
    Jun 17 2018
    AZ Member #
    420830
    Location
    Colorado

    Quote Originally Posted by Theiceman View Post

    Ran fine today all day but the car is thirsty !! Could be me lead foot though.
    What gas mileage are you getting? If it's quite low (below say 23 highway) I'd guess you have an injector staying intermittently open too long.

    Have the injectors ever been replaced? Was the previous driver really light on it? Mine was, and that's why when I finally got after it (after replacing timing components, drain/refill of transmission, and new suspension), an injector gave up, and got stuck fully open.

    Some times they intermittently get stuck open, which can result in rough idle, temporary no-start, random misfires/loss of power, etc.

  7. #7
    Active Member Three Rings
    Join Date
    Jun 17 2018
    AZ Member #
    420830
    Location
    Colorado

    Quote Originally Posted by Theiceman View Post

    My son pulls the code, fuel pressure regulator out of spec.
    Ah, missed this, sorry. Ya, sounds like that is indeed dieing. Still might consider some BG44K in case the out-of-spec is caused by some small clogging/etc.

  8. #8
    Senior Member Four Rings Theiceman's Avatar
    Join Date
    Feb 15 2016
    AZ Member #
    368804
    Location
    Cambridge Ontario

    I nay have set a reliability record !

    Sounds like a plan !! I was looking for the fuel filter. What a PITA. if im going into the tank its getting a pump and filter regardless, im only going in there once !!
    So should at least be a good starting point.

    Of course previous owner habits are unknown. One owner dealer serviced, i have all service records and to be honest not a lot went wrong.
    Tons of highway driving with 200k km in just over 4 years. Had complete brake job only once in that time and still lots of meat on them.
    Just passed the safety with flying colours .

    The fuel injector theory i find interesting. No starting issues at all. I will keep an eye on it for sure. Still on my first tank of gas so will report on actual milage.

    Thanks guys. All info much appreciated.

    Sent from my iPhone using Audizine
    Last edited by Theiceman; 09-17-2018 at 12:43 PM.
    2014 Nissan Murano
    2006 A4 2.0TQ 6spd
    1978 Porsche 911SC Targa
    1976 Yamaha XS 360



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