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Poor MPG Audi a4 1.9 TDI 130 BHP Sports 2004 / thermostat??!

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Sam84, Feb 8, 2012.

  1. Sam84
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    Sam84 New Member

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    Hi,

    New to this so apologies if it's the wrong section, feel free to tell me where to move it.

    Ok I got an Audi a4 54 Reg 130 BHP tdi ( non quattro ) the other week, I've noticed my engine temperature rarely goes above 72 degrees, unless idle on the driveway, which then reaches around 82,then when i pull off goes back to 70 again. I've read on here it may be a stuck open thermostat, or a few sensors such as coolant, engine etc, i've checked my heaters and 21 degrees does feel the same as 29 degrees...

    My MPG is terrible, i've put 10.3 litres in and gotten 72.5 miles out of her, according to torque cars 32 MPG, something must clearly be wrong, i don't always drive her hard and change just on 2k rpm on flat / downhill.

    Yes it's cold outside in Cornwall where I live, 3 in the day today, and -1 when i have been testing it on hills- but most days 6 degrees, sometimes even 10 and it's still stuck on 70 even after a 30 minute run.

    any advice would be great :)
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  2. quattrojames
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    quattrojames Moderator Staff Member Moderator

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  3. Sam84
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    Sam84 New Member

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    thanks,

    OK seems mine is the worst, can't be normal, i just got rid of my R reg tdi golf I had 50 MPG consistently :sorry:
    #3
  4. sinic
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    sinic Audi WAudi

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    I consistently get 650 to a brimmed tank full and still a bit left but that's if I change up under 2300rpm. It goes down to 380 per tank if I'm driving like a twat.

    I've had 700 once on a long run to Scotland at a steady 85mph - was well pleased with that.
    #4
  5. iyrix
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    iyrix Member

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    I was get decent MPG, but with the cold weather mine has also dropped a lot.

    The temp on mine now goes down to 70 as well. I changed the Temp sensor last year, so might look at that again along with the stat.
    #5
  6. Sam84
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    Sam84 New Member

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    I'm taking her to AVS in Redurth, Cornwall, gonna see what they say, 96 view and 4 replies?? Come on ppl...
    #6
  7. benjie
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    benjie Member

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    I would change the thermostat and coolant temperature sensor - especially if you don't know when they were last changed. They're both cheap and easy fixes. I would expect the mpg to go up after that.

    Get that done, then see what happens and post back.

    (Also, if this garage you're going to has any diagnostic software, get them to plug it in and check for any fault codes)
    #7
  8. StuG808
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    StuG808 1.9tdi130 Avant FailWheelDrive

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    Mine also runs at about 70degrees and MPG (on the computer at leat) is a bit less than expected, so a thermostat change is on the cards.

    How accurate is the trip computer for MPG calculation? Previously I have kept a record of mileage between fillups and litres used to give me an accurate reading, so I will continue this with the Audi and see how it compares with the computer.
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  9. Sam84
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    Sam84 New Member

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    I'll let you know what happens, it's booked in thur, Yes they have VAG-com and others, need to check why my air bag light is on, and if not already done by then figure out what's gone wrong to have no de-mister working either, guessing it's one of the motors ( 8E2820511G ) but we'll see.
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  10. Sam84
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    Sam84 New Member

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    My last MPG reading was bang on 40, over 10.5 litres. and this was taking it easy, but again it never rose above 73 degrees. On my sports model I can only get miles to go before I run out??? Looked on the stalk there's nothing to flick to MPG current/ average etc, or is it somewhere else? I normally do 10 litres every time, and use torque cars mpg calculator, it's v good. Quick MPG calculator - Calculate miles per Gallon

    Mine seems accurate i think, it's a bit up and down. I can start with say 90 miles to go then it'll drop to 60, 50, then BEEP fuel time. Do you run yours to the reserve light comes on and then top up?
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  11. benjie
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    benjie Member

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    Airbag light - commonly caused by wires under driver's seat, check it's still connected/not being pulled.
    Demister - if they have vag-com (now called vcds) get them to go into 8 Auto HVAC, then Basic Settings and perform a flap alignment - this might cure it.
    #11
  12. marktdisport
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    marktdisport Active Member

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    the servo motors are most common to fail m8 the green linkage one, ive removed mine so flap open all the time as servo's are around £100 as ive been told
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  13. Sam84
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    Sam84 New Member

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    thanks a bunch for the advice, I'll see what they can do Thur, and i'll try to sort the smaller bits myself.
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  14. benjie
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    benjie Member

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    The demister is easy - take the glovebox off (pop dash end panel off, 8mm bolts, 6 of them - 3 at the bottom, 3 just inside the glovebox door at the top, don't forget to unplug the glovebox light wiring) - motors are in there. Keep an eye out on eBay for them as I got one for £27 delivered.
    #14
  15. StuG808
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    StuG808 1.9tdi130 Avant FailWheelDrive

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    That link is just like what I was doing, just taking a note of the mileage and litres put in (and cost) when I put fuel in it, then used my own nerdy spreadsheet to work it out. It's a bit of a hassle noting it all down though, but a bit more accurate that some types of reading, ie from the fuel empty light.

    My stalk brings up to MPG readings, a current and another that I assume is an average based on the trip reset.
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  16. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    I use fuelly.com to record my mpg. I get into the habit of taking a photo with my phone of the clocks just before I fill up and reset the trip at the same time, then when I'm at the computer to enter the data I can use the receipt for the amount of litres, and look at the photo for the distance. Very simple and works well for me.

    If your mpg on the DIS is way off you can reset it with VCDS.

    Memory 1 is reset everytime the car is stopped for two hours or more, so that reading is 'generally' for your current journey.

    Memory 2 is a cumulative total.

    In case you don't know, there's a button under the stalk to flick between the two memories which are indicated by a 1 or 2 in the display. Press and hold this button to reset memory 1.
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  17. StuG808
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    StuG808 1.9tdi130 Avant FailWheelDrive

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    Ah, I didn't know that, so Memory 1 records MPG average for the entire history of the car?
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  18. Biggie A3
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    Biggie A3 New Member

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    My MPG has dropped from 45 to 35 average in this cold weather.. some of it is due to leaving my car to defrost on the driveway though.. It's just had a full service and all filters changed.. so guess it's nothing to do with fuel/air filters being clogged. With the Airbag light.. mine just got re-set and the fault code was due to the switch in the glove compartment for the passenger side airbag being triggered. I think this might have been when i slammed the glove compartment closed...! lol.. (the soft close has broken on it)... As you say, my old Golf 115PD would do 43mpg even if you thrashed it's nuts off for the whole tank.. I think the newer VAG engines are maybe a little more thristy.. for the increased power..
    Pretty easy to work out MPG.. approx, (give or take) 4.5 litres per gallon.. then record milage.. I always do a quick mental check to make sure the trip computer isn't telling me lies..! :)
    #18
  19. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    It resets every 200 hours or something I think.
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  20. StuG808
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    StuG808 1.9tdi130 Avant FailWheelDrive

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    Ah, sorry I meant Memory 2? This is an average of the MPG from leaving the factory?
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  21. Nessy
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    Nessy VW + Audi mad

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    I'd say a thermostat change is definitely in order.
    On my previous car (an 80 TDi Avant) and my current B5 A4 the water temp gauge always sits bang on 90 once warmed up and stays there.
    Don't get an aftermarket thermostat either, from the likes of GSF etc, as these have been known to be faulty out of the box, the Genuine article costs less than £20 and are much much better quality.
    I replaced the thermostat on mine last week due to a fluctuating temp gauge and this cured it totally.
    On the B5 Climate Control panel you can display the real-time coolant temp (as being measured by the Coolant Temp Sensor) to see if this matches the temp gauge reading, if it does ( and I believe there is a buffer of about +/- 10 degrees allowed beween the 2 ) then it suggests the CTS is working OK, which was the case with my car.
    I wonder if this facility is available on the B6 CC panel?
    On the subject of mpg, the OP's is very low IMHO, my car puts out approx 140bhp and does 50-53 driven gently and 47-49 when with more of a heavy foot.
    Last edited: Feb 13, 2012
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  22. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    I knew what you meant so I didn't bother correcting you ;)

    Memory 1 resets after the car is stopped for two hours.

    Memory 2 is a cumulative total based on the last 200 hours driving (I think) - it's in the handbook I'm sure.
    #22
  23. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    It isn't I don't think.
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  24. Nessy
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    Nessy VW + Audi mad

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    Really?
    The same sequence of button presses seems to unlock this 'secret' menu on various former VAG group models , despite their very different CC panels eg TT and Passat B5 Climatronic.
    Bit of a backward step if it doesn't work on the B6 IMHO.............
    #24
  25. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Yes agreed, I've heard mention of it numerous times, but never heard of it being available on the B6.
    #25
  26. Nessy
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    Nessy VW + Audi mad

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    Have you tried it?
    Its very easy.
    Press and hold air 'Recirc' button ;at same time press the button showing airflow up arrow ( the one to get air at base of windscreen vents).
    Display should read 1c.
    Then press temperature + or - button repeatedly to get the code reading you want eg 49c which on the B5 is coolant temp.
    Press 'Recirc' again and the value of whatever is being measured is displayed.
    Theres a big list of the codes available on the internet, but I'm sure you're aware of that,lol........
    #26
  27. Sam84
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    Sam84 New Member

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    There is no Button/ Memory button on my stalk, Defo the wiper stalk??! it's just flat. mine's the sport version, seems crap for extra gadgets, quite basic. my 98 R reg golf had it as it was the SE, should all a4 b6's have this factory fitted??! I think memory 1 resets every 2 hours, in my golf it did, and my a4 manual said it should, what I read a few days ago. Memory 2 resets by the user I believe?
    #27
  28. Sam84
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    Sam84 New Member

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    Did just that today, think i had 5 bolts, but anyway I managed to fiddle with it, ( the green arms ) got it working again, understood how it all worked, and applied some WD-40, tried 20 times and it's proving to be working well, may have been stuck, it made an obvious tick tick noise when attempting before tweaking/spraying.

    I'll see how it goes for the rest of the week, I know what I need and will eye up ebay, and also contact ppl breaking a4's on there too. I'm in need of a new glovebox so if it breaks again it's not the end of the world, do both at once type thing.
    thanks again for the advice.
    #28
  29. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Sport models didn't come with full DIS as standard, it's a fairly simple retrofit, lots of threads on it.
    #29
  30. StuG808
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    StuG808 1.9tdi130 Avant FailWheelDrive

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    Ok, my 'Memory 2' reads 40mpg, which isn't great.

    On a different note, my dash computer is in German even though the RNSD is in English. Although the 'panzer' effect is cool, is there anyway to change it to English?
    #30
  31. benjie
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    benjie Member

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    Yes. You need VCDS. Open the program, click - Select>17-Instruments>Coding>Ensure the 5th digit ids a number 4. (Will probably be on 0 at the moment)

    EDIT - I'd also go for something more permanent than WD-40 on the motor - some kind of grease that's not a spray, one that's more like jelly!
    #31
  32. Sam84
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    Sam84 New Member

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    I definitely will if it gets stuck again, I'm sure i can get hold of some good stuff from gf's dad. But i was in a hurry for it to be fixed. Wish I had the MPG selector.

    So my MPG with 3 x latest fill ups of 10 Litres has been, 32.5 MPG, 40 MPG and today on a good run 42 MPG. engine reached around 82 degrees today but then dropped again whilst driving, so Thursday will be interesting to see what the Audi specialists decide what needs doing.
    #32
  33. benjie
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    benjie Member

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    32 is seriously poor. 40/42 - ok for me (4wd) but not for you. I don't have the car in front of me, but my money's on thermostat. I got about 3-4mpg when I did my coolant temperature sensor and thermostat. Now get 50mpg on a long, careful run (in moderate weather - cold conditions reduce mpg too!)
    #33
  34. StuG808
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    StuG808 1.9tdi130 Avant FailWheelDrive

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    I tried this but it only changed the AC temp reading from degrees to farenheit.
    #34
  35. stu_m
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    stu_m Active Member

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    Only works on the b5 on the b6 you have to use vagcom
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  36. Sam84
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    Sam84 New Member

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    the chaps at AVS in redruth Cornwall, ( very good service + price for any one nearby ! )have put it down to the thermostat, due to be removed and new one fitted on the 28th. Also coolant temp sensor may be replaced but VCDS/ Vag com hasn't shown any fluctuations with it. So this ought to sort out my MPG issues ./ engine never going to 90 degrees unless static for a while.

    Also AIR BAG light on the dash was triggered by the sensor under the passenger seat, this has been tightened and light has been turned off via Vag Com, may need a block putting on to avoid it coming back.

    Update on repairs on 28th, and MPG update a few days after that.
    #36
  37. pink.teg
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    pink.teg Member

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    hi all

    nice read ,and after reading all this ,i have somthing to ask?.
    my 1.9 quattro never ever reaches 90.c sits on 73.c and if im in london traffic then may get up to 85.c
    will this damage my car in any way. my MPG is around 32 and long run in the 40's which im ok with after driving the scooby which was
    hard core filling up.
    im getting it remapped next week ,and would like it all to be spot on before i do this .
    so the two item's need doing are coolant temp sensor and thermostat..please comfirm.............:wtf:

    thanks alan
    #37
  38. stu_m
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    stu_m Active Member

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    Sounds like the stat or the sensor has gone and its running cold map all the time I would replace both for peace of mind before the remap
    #38
  39. Sam84
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    Sam84 New Member

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    I got the exact same issue pink.teg and my thermostat's going to be replaced soon, and possibly coolant temp sensor if that's gone too. What I've learnt with my problem is the thermostat is permanently open, meaning coolant is constantly being released around the engine, despite the engine temp, which it's meant to do at 83 degrees and warmer, and then keep it at a constant 90 degrees once warmed up. - thus running on full choke as well, explains the crappy MPG i'm getting anyways.

    Get this sorted for sure before your Remap, if you get a rolling road figure before and after would be great to see the figures/graphs
    #39
  40. pink.teg
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    pink.teg Member

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    Yes will do
    48.38 p for the two parts plus clips and rubber o rings
    will get them fitted thursday now and remap early next wk

    Thanks all
    #40

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