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Starting the S3 with low fuel stutters

Discussion in 'A3/S3 Forum (8L Chassis)' started by Hadders, Sep 28, 2011.

  1. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Jan 29, 2014]
    Am tending to agree with you here, My car was sat for 12hours over night. Outside temp was 5degrees and it would not start if I turned the key and left it. It would try and then the revs would die off and engine stall. It did this twice and on third attempt I blipped the throttle to get it to 1200rpm and its perfect stopping just above 1000rpm while the auto choke is on.

    I drove the car about 300yards and switched it off (temp gauge had not moved yet), I then returned to the car about 45mins later so it should still be basically stone cold and the outside temp was the same. stood outside the car turned the key and it starts straight up and sits just above 1000rpm no probs at all.

    So this lead me to believe it is something to do with the fuel pressure dropping off over a period of time and then it takes a bit of help to re prime it on the next start.

    Any other thoughts?
    #41
  2. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Jan 30, 2014]
    Right today car was proper **** at starting

    So it stood overnight and outside temp was about 4degrees when I cam to start it, turned key and even with me trying to give it some revs it almost died it does 3-4secs of stutters then it lets me rev it above 1000rpm and all is good as it settles and idles fine.

    So as it seemed worse this would indicate to me that as the fuel level gets proper low eg in the red on the gauge it struggles more but it might also be where I fiddled with the FPR and CTS yesterday. So to see if I can alter the results I have left the petrol level at the same in the red on the gauge and I have removed my FPR again and adjusted my extra o ring I added to beef up the crappy green one, it seems like it makes a better seal now. I also swapped back to my original CTS.

    So will see how she starts 2moro.
    #42
  3. s3mad_dude
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    s3mad_dude Noggies ruuuule!

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    [Jan 30, 2014]
    Interesting tests - it certainly sounds primey/pressure related doesn't it? Hope you get it sorted and let us know how you get on tomorrow :)
    #43
  4. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Jan 31, 2014]
    quick update

    Fuel light now on and yup just as bad to start after being left overnight.

    Gonna stick some fuel in 2moro so that will help see if it is a low fuel issue or not in my car.

    Also gonna see if I can find another FPR to try or at least get a new proper o ring on mine

    the hunt continues......
    #44
  5. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 1, 2014]
    just to keep this updated lol

    Last night after being at a friends house for a few hours it spluttered again whilst trying to start.

    So today it has had a full tank of Vpower put in so will monitor how it starts with the fuel level up high and see if its different with the original CTS fitted and the FPR as is with the new o ring I put on.

    Am also gonna get a new CTS just as a side as my car does take longer to warm up than it used to on the gauge and this are not very expensive. Also gonna try another FPR with hopefully a better o ring as have one coming Monday that is a spare.

    will keep this posted as and when
    #45
  6. daz-20vt
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    daz-20vt Well-Known Member

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    [Feb 1, 2014]
    My car always used to start fine Then almost immidiatly start to stutter for around 5 seconds then be fine. I changed the cts and it is fine now.
    #46
  7. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 1, 2014]
    Well am hoping this will solve mine too so will see once the new CTS arrives.
    #47
  8. russwuss
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    russwuss Active Member

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    [Feb 1, 2014]
    Interesting reading.... mine also struggles to start with the exact same symptoms as you have noted however my CT gauge is the opposite - 2 minutes of driving the car from cold and the gauge is at 90degC - i'll order one also and hopefully it fixes mine :) thanks for the update.
    #48
  9. voorhees
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    voorhees Moderator Staff Member Moderator

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    [Feb 1, 2014]
    I had this on mine and never did sort it despite changing plugs,gaskets,lines,sensors also had Audi look at it as had warranty,their verdict after five day was maybe it was my map,be interesting to see a solution to this.
    #49
  10. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 2, 2014]
    Well today with a full to the brim fuel tank and an outside temp of about 9degrees (so not that cold really) I turned the ignition on and turned the key to start and once again it splutters drops to about 250-300rpm and almost dies. So I step on the loud pedal and it does nothing for a sec or 2 and then lets me rev it up past 1000rpm and its happy as larry ticking over just above 950rpm on its auto choke.

    So it is slightly better with a full tank but obviously this cannot be my issue as the spluttering continues. This is defo leading me towards the CTS at fault as the car is having issues getting is mixture right on coldish starts after being stood for a few hours or more. My car also takes a good 5-7 mins of town driving to get the needle to say 90degrees even though I have hot air out of the vents when its indicating 65degrees on the needle.

    So once I get my CTS fingers crossed it solves my problem. I am also trying a different FPR 2moro as I still think the old o ring on mine isn't helping matters.

    tune in 2moro for more starting issue fun :)
    #50
  11. s3mad_dude
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    s3mad_dude Noggies ruuuule!

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    [Feb 2, 2014]
    Wow 950? Just as a comparison mine, as soon as it fires, the rev counter comes alive and goes straight up to about 1200 rpm and starts reducing pretty quickly once I've started driving. I know older cars (ok im going back to my 205 GTi days) had supplementary air devices as part of the auto-choke. What do we have on our S3s? Is it something built into the fuel injection, which in turn is controlled by the ECU right? Could custom maps have affected this?

    I'm literally just punting in the dark so it's highly likely I'm talking ****! Anyway, I'll be tuning in tomorrow! :p
    #51
  12. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 3, 2014]
    If it works right it does the same as yours 1200rpm and then steps down incrementally as it warms up.

    Today it didn't die on first start but did still splutter but I didn't have to help by touching the loud pedal.

    So got the fpr out and the o ring was in pieces so defo not helping. Luckily borrowed an o ring form another FPR which again isn't 100% perfect but better than no o ring at all.

    Also my CTS should be here this week which I hope will make a difference but will see how it starts tomorrow with its better fpr o ring anyway just to keep up with the results.
    #52
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  13. daz-20vt
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    daz-20vt Well-Known Member

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    [Feb 3, 2014]
    I have my fingers crossed for you. Your syptoms are exactly as mine were. Mine would splutter so bad it would struggle to pull through it even with a dab of throttle. You ordered an oem cts?
    #53
  14. Sam_
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    Sam_ Down under

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    [Feb 3, 2014]
    I cleaned my throttle body and done a throttle body alignment in VCDS and mine seems to be behaving now. It wasn't all that dirty either (fitted an air/oil seperator ages ago) but still seemingly made a difference.
    #54
  15. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 3, 2014]
    Cheers for all the support :)

    Am hoping I can solve this with some sort of conclusion for others to try but its a work in progress lol

    Might give the throttle body alignment trick a shot though as not tried that yet cheers Sam.

    Back tomorrow with any updates.......
    #55
  16. Sam_
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    Sam_ Down under

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    [Feb 4, 2014]
    It's worth doing anyway. It always seems smoother afterwards but it could well be placebo.
    #56
  17. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 4, 2014]
    Right todays mini update....

    So after yesterdays mini tinkering session in the evening last night I came to start the car this morning outside temp was 4.5degrees and its was a lot better :) it did a tiny splutter like drop to 500rpm and then (with no assistance from me) rev`d to 1200rpm and did the normal step down as it warmed up.

    So first conclusion will be the FPR seal may well be part of the issue as I think without a good seal if the car is left for a few hours (eg overnight) then it can loose pressure to the fuel rail which obviously wont help starting a car.

    It still took longer than I would expect to warm up to 90degrees so I hopefully the new CTS should help that and maybe be the last step in solving my crappy cold starting issue.

    Still gonna do the TB alignment later too as its easy to do with VCDS.

    keep tuned.....
    #57
  18. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 5, 2014]
    Todays update and its good news :)

    even though I have not fitted my new CTS yet I did the same as I have been doing the last few days when cold starting but low and behold it was 8 degrees out and it fired straight into life no splutters at all sat at 1200rpm and did the norm as it warmed up (all be it slowly lol).

    So in conclusion I have no definitive answer as yet but its defo worth checking the FPR and that it is sealing properly and maybe a TB alignment too.

    Will update this once the CTS is in to see if it improves the warm up time and of course if the splutters return
    #58
  19. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 6, 2014]
    Still no CTS but it is in the post to me...

    But 2nd day and the car starts perfect :) outside temp was 5.5 degrees and opened door stuck key in turned instantly (no wait for pumps to prime or anything) and purrs straight into life and does the normal routine. So defo a marked improvement on my car in the starting process and hopefully it will continue. Will monitor as the fuel level drops as still on 3/4 of a tank at the mo.


    *mini update* CTS arrived in late afternoon post :) so as car was cold I have put it in and will see if that helps the warm up time.
    Last edited: Feb 6, 2014
    #59
  20. fazer0
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    fazer0 Member

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    [Feb 8, 2014]
    Any definitive answer to this yet, as my car only seems to do this when its under a quarter of a tank but will be testing it to see if it does it at any other level.
    #60
  21. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 9, 2014]
    Nothing definitive as yet sorry.

    I will say I still think it has something to do with losing fuel pressure after being sat for a bit. So pop your FPR out of the fuel rail and give the O-rings a check as the smaller one on mine was not in great condition and changing it greatly improved the starting in my car.

    MY new CTS has made no difference in how my car warms up so I will assume my original one was fine and just keep it as a spare.
    #61
  22. russwuss
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    russwuss Active Member

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    [Feb 9, 2014]
    My next stop will be FPR to... I fitted the new CTS on Saturday and this morning it took a good 5 seconds to even start, but revs were perfectly fine when it did start. So I'm on the hunt for a new 4 bar FPR, cheaper than buying new injectors and not looking for anymore than stage2!
    #62
  23. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 10, 2014]
    I have ordered what I hope are the correct size O-rings form the FPR as found some on ebay I think so just waiting for them to show up as currently have 2 smaller o-rings on it trying to do the job which they are not that successful at.

    So currently the issue has returned where it will not start easily after being left for a longish period of time and the cold weather does not help. Once running though its lovely and if turned off and started again within a couple of hours it starts on the button.
    #63
  24. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 12, 2014]
    O-rings have arrived today and looks like I can use a ruler as they appear to be the correct size.

    So popped out the FPR and as suspected my o-ring bodge job had not worked as it had slipped up the FPR so again wasn't sealing well. I am pretty sure (99%) that this is why my car does not like starting after being sat for a while especially if stone cold too.

    So will see how it goes with the new beefier o-ring installed as if I starts up fine for the next couple of days I think I will be able to say this was my issue.
    #64
  25. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 15, 2014]
    New o-ring has defo made the issue a lot better. In the end I replaced both the smaller and bigger O-rings on the FPR as that way I felt like a good seal when I re-installed it into the fuel rail.

    I also noticed that my battery was a little flat (guess maybe cos of the starting issue?) so that's been on charge for a good 18hours and has come back up.

    So car was sat for 18+ hours stone cold and blipped the key stood outside the car and it purrs into life no stutters at all :)

    So to conclude the main things I have done to try n fix this prob are :

    1. Check the fuel rail is sealing properly which basically means check the FPR o rings and replace if necessary.

    2. See that the car warms up to 90degrees after aprox 10mins and stays there (if not maybe try a new CTS)

    3. Throttle body alignment using VCDS (gonna whip mine off at some point and give it a clean too)

    4. Check the battery is running at optimum charge level

    If all these things are done and working as should be hopefully it will help others solve any cold/left for a longish period of time starting issues.

    Rob
    #65
  26. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 15, 2014]
    Sat for another 5 hours+ and engine has only run for 2-3mins in the last 24hrs total and once again starts perfectly, straight to 1200rpm and then does it warm up process :)

    will confirm that it starts ok again 2moro but results look promising........

    Oh and just as a side note currently my car has just over 1/4 of a tank of fuel too and was 6degrees outside temp
    #66
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  27. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 16, 2014]
    Last daily update (hopefully)

    Car sat overnight so 12+ hours came outside to start (outside temp about 10 degrees) and once again she purrs into life not even a slight stutter Woot Woot :)

    So will run the fuel tank to the petrol light if I can and keep monitoring the starts just incase anything does change when the fuel level gets lower.

    But fingers crossed I fixed it :)
    #67
  28. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Feb 21, 2014]
    Right hopefully my final update to this :

    After my car being fine for a couple of days it started once again to stutter slightly on the morning start. As my battery had recently gone flat I decided that although it did re-charge it must be a least 5 years old and not great quality it was time for a replacement. So got a new Bosch S5005 (its the 027 style battery) which had a much better amperage rating for cold starts.

    I also took the opportunity to replace the fuel filter as its cheap as chips (under a £5 delivered from ECP)

    So now car has under 1/4 tank of fuel heading for the Empty mark and its once again it started perfectly today :)
    #68
  29. mattyboy199
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    mattyboy199 Active Member

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    [Jun 25, 2014]
    well the S3 is struggling to start when the fuel is low, low fuel = low pressure, if the pump is worn it would allow fuel to back up. So looks like a new pump is required, i saw a how to guide but cannot find it can anyone help ? oh forgot to say if i fill the tank no issues at all.
    #69

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