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Thread: Audi A3 2.0TFSI (BWA) Intermittent starting issue

  1. #11
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    Hey Jack.
    Very kind of you to chip in with some good information. Hopefully you're onto something here mate.!

    TBH electric circuits and wiring are something I'm not too familiar with (sorry). Can you help me out with what I need to do, and where these items are and how to check them.
    I understand if you don't want to commit too much time for someone like me, but I'm hoping that you enjoy resolving these kind of problems for your little reference book for future use ;O)
    I understand that Terminal 15 is to do with the ignition switch (I think), and Terminal 30 is more to do with the battery side of things? Terminal 50 to do with Starter motor solenoid.?
    Is the J271 relay under the drivers side footwell panel, and the J317/J757 relays in the fuse box alongside the battery under the hood.? and are these what I ultimately need to check.?
    Are there also fuses associated with these relays that would be worth checking first.?
    Also, would the car still start if any of the above were faulty (or can they gradually wear out and essentially die.?)
    Many thanks for your time, I hope you can be of further assistance.
    All the best,
    Rob.
    Last edited by Sharkie1976; 05-15-2015 at 06:42 AM.

  2. #12
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    Hey again.
    I'm going to look at the current flow diagrams on the workshop manual tonight.
    I think Terminal 15 is Relay R1 under the bonnet. If I recall I did ask on another forum last year (but didn't get a response) as to what this relay is, as it was getting rather hot to touch.
    Hopefully this ties in with what you have described Jack. Should this relay be getting quite hot, or does this show that it could potantially be faulty/intermittent.?
    Thanks,
    Rob.

  3. #13
    NostraJackAss Jack@European_Parts's Avatar
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    I would be happy to help.......

    Please get and RTFB the repair manual.
    Read how to read WD or see this link Jef made.

    http://forums.ross-tech.com/showthre...d+wire+diagram

    This is a nice link Uwe left the other day.

    http://en.wikipedia.org/wiki/DIN_72552


    Terminal 15 is B+ switched voltage..........whether via switch such as ignition switch or switched relay!

    Keep in mind that there are multiple Terminal 15 and 30 relays not just one leg current track anymore.
    ECU supply relays and FP or load reduction relays........... may in fact be switched after a controller is powered up, with a preliminary input or virtual terminal such as a wake via the Gateway 0x19 or 0x09 BCM.

    Keep in mind ground is what is switched which why I say check them!

    Beware:

    The term ASSHOLE ground is very important to understand and test proper.
    This is where you have a ground with a meter or test light through a device, however an incomplete ground........
    I call it this because you will always feel like an asshole after you find it and thought you tested it correctly......... when you didn't.

    In addition to things such as voltage drop.......... during crank under load, and loss of needed current to operate a controller to cold start.

    I often install voltage stabilizers with capacitance in my race cars on specific tracks to maintain a clean current for such clarity.

    It is also why the OEM has moved to duel isolated BDM battery managers for such common conditions during the load of cranking.
    Last edited by Jack@European_Parts; 05-15-2015 at 10:40 AM.
    European Parts Emporium/Performance / Immobilizer Solutions EPE
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    Above Magic! No Written record, AUTO-SCAN or Appointment = NO HELP!
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  5. #14
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    Hey Jack.
    Thanks again for your reply and suggestions. It does sound very complicated, but I'm going to have a good read of the links you kindly directed me too.
    Once I have a better understanding, and can follow the diagrams from the manual I'm hoping it will help ALOT.!
    Sounds like you certainly know your stuff mate. I wish I was as clever.
    Wish you were in the UK and I'd be straight over to you and pay you kindly for a check-up ;O)
    Anyway, I have some reading to do and looking forward to it.
    Thanks for your time today mate, appreciated.
    In the meantime, do relays generally get pretty hot.? This is the one I mentioned a couple of posts ago.

    Cheers bud.
    Rob

  6. #15
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    Well, I've had a good look through the manual and the wiring diagrams.
    I have managed to find out some info, but not really sure whether I'm on the right tracks or not (probably the latter, lol).
    J271 ecu relay is Relay R1 under the hood in the upper fuse/relay holder.
    J271 relates to fuse 23 (5amp) also in the upper holder (terminal 30).
    J757 is Relay 4 & fuse 42 (5amp) also in the upper holder.
    J271 & J317 is also connected via fuse 10 (5amp) in the lower holder.

    So, how am I doing?? I don't mind if you have to tell me I'm doing crap, lol. It's my first attempt to try and work through this with no experience.
    Couldn't seem to find anything as regards to relays and Terminal 15.
    Hmmmmmm!!
    CHeers,
    Rob

  7. #16
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    Hey Jack.
    Well, I have gained some knowledge, but unfortunately thats about all.
    I have tested every fuse inside and outside of the car. Also removed every relay and tested with a 12volt supply whilst checking the continuity. All switches in the relays work fine.
    I guess I should have checked the earths first, may be the next thing for me to check.
    I am starting to lean towards it being a Carbon build up issue, which seems to be very common with Audi direct injection models, and does cause poor starting. I think it's down to the fact that the carbon absorbs the fuel on first starting, therefore a stumbling start. I may be wrong and I hope I am, as it costs between 450-600 to get the carbon removed from intake valves/ports and inlet manifold.
    When weather permits, I'm going to check the earths and then check if there is too much voltage drop on the battery when cranking the engine.
    Would appreciate it if you could comment on what you think about the carbon buildup and my next steps.
    Many thanks,
    Rob

  8. #17
    NostraJackAss Jack@European_Parts's Avatar
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    Well you did good so far with the absence of the auto-scan.

    An auto-scan is always helpful with true logs............

    So far nothing.

    Intakes do get clogged with carbon, and yes carbon acts as a sponge for cold starts.
    Personally I doubt it is it for sporadic condition though.
    European Parts Emporium/Performance / Immobilizer Solutions EPE
    Certified Master Trained NY/BAR/BAD 7076062/ASE/SAE/NASTF Legal Factory Authorized/Licensed GeKo/FaZit # 403738
    Specializing in Custom Services IE: "welding-fabrication" / EPA-SMOG Update or Pass-Thru-Programming / Data Transfer / Immobilizers & OEM Quality Parts
    Above Magic! No Written record, AUTO-SCAN or Appointment = NO HELP!
    www.FixMyEuro.com <<<<<CLICK HERE! or vwemporium@aol.com ( JPPSG & Unverified members need not PM me & Please don't email or call facility for free tech support...use the forum )
    Getting you CONTROL again of your property - TAKE IT! In Conjunction with.........

  9. #18
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    Hey Jack.
    Lol, Uwe kindly linked my auto scan on page 1, so it is theoretically there.
    The only relays I haven't checked is the ones under the plenum chamber, where rain etc runs below the windscreen, and I believe 1 fuse also resides there. Cover is a bit of a pain to remove tho. I have also cleaned out the throttle and it did have deposits in there. Car started very well for 2 days, but now rough like before. Bloody car, lol.

  10. #19
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    Hey Guys.

    It's been a while and I thought I'd update the thread with how I fixed the problem.
    Ok, one day I came across a BMW forum and there were quite a few people complaining of the same/similar issue. They found that it was in fact Shell V-Power Nitro + (RON 99) causing starting issues.
    I thought to myself I'd try changing fuel brand as from what I read, the higher the RON figure, the harder it is to combust.
    Anyway, to cut a long story short, I ran the tank down low and filled with Esso Supreme 97 and hey presto 2 months down the line, I haven't had any more hard starts. It fires up so much better now.
    I know of lots of people that swear by Sheel V-Power, and I thought it was a nice fuel, but my car just doesn't seem to like it at all. I have used it for over a year and have always had this starting issue.

    Hope this helps somebody out there with a similar problem.
    Regards,
    Rob.

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  12. #20
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    seems similar to a bad check valve in the lpfp . it should make around 6.5 bar on low pressure. do output test on low pressure fuel pump with mechanical gauge in line its the black fuel line not blue. then shut off car and the fuel pressure should not loose more than 3 bar in 10 minutes. if so there is a leak. you can isolate the leak by clamping off the hose going to the engine and repeating the procedure to rule out a leaking fuel injector.

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