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What affects MPG???

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Johnjones, Jan 12, 2013.

  1. Johnjones
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    Johnjones Member

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    I have an Audi A4 1.9 tdi sport estate.
    It does 47 mpg on motorway runs...Not bad, but I was hoping it would be a little better. I do 75- 80 mph all the time and accelerate gently. What can affect the MPG? (Apart from the obvious ones like tyre pressure, poor running, etc.) It runs smoothly with no fault codes or known faults....Could the MAF or MAP cause this without symptoms??? The coolant sensor was recently changed for one off ebay and the thermostat was changed too....it now sits at 90 degrees most of the time.
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  2. stu_m
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    stu_m Active Member

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    if your getting 47 at 70-80 then theres nothing wrong there its about right

    try slowing down to 60-65 and it will increase

    when a maf is on its way you dont get no difference in the drive

    the cold effects it too
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  3. Johnjones
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    Johnjones Member

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    Thanks buddy! Is it worth changing the MAF or should I wait until mpg drops substantially?
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  4. stu_m
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    stu_m Active Member

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    I would get it checked with VCDS first if you suspect it is bad
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  5. BahnStormer77
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    BahnStormer77 BahnStormer

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    sounds about right... I bet you get around 55-60mpg at 60mph, so try slowing down if economy is THAT important.... personally I'd settle for 47mpg at that speed.

    I get about 60mpg at a steady 50mph, 40mpg at 70mph, 35mpg at 85mph and 30mpg at 100mph.
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  6. demus
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    demus Fire in the hole !!

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    All big electrical loads will drop it too, demisters, lights, fans etc.. all the stuff you need this time of year. 47 isnt far out, most I've ever had from mine is 50..
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  7. Johnjones
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    Johnjones Member

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    Sorry guys, i should have said i'm getting 44 mpg at 70 mph....I'm wondering if the Maf might need changing?
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  8. Johnjones
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    Johnjones Member

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    Even at 60 mph, it still stays late 40s on the trip computer....I don't have any fault codes. Are tests any tests or easy parts to change to see if that helps???
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  9. stu_m
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    stu_m Active Member

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    forget the DIS work your mpg out tank to tank
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  10. Johnjones
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    Johnjones Member

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    Yep I did that....590 miles and put 60 litres in...= 43.76 mpg. That was mainly motorway at 75 mph.
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  11. fallmonk
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    fallmonk Turbo Sport

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    How much fuel economy do you think you loose with keeping heated leather seats on ?
    Anyone ???
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  12. pauldazzle
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    pauldazzle Active Member

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    Coolant Sensor off ebay:banghead: :no:
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  13. Johnjones
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    Johnjones Member

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    Do you think that might be causing trouble Paul? Should i get the gsf one for £17
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  14. Johnjones
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    Johnjones Member

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    My father's B5 currently has the heated seats on all the time and he's still averaging 51 mpg and that's mainly running around the villages, so I guess it has little affect.
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  15. stu_m
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    stu_m Active Member

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    its best to replace with OE all the time if you can

    But Im'm not sure you have a problem at all
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  16. Johnjones
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    Johnjones Member

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    Thanks Stu, it's just my brother has a 115 pd and gets 55 on motorway at 70....i was hoping for similar. Does OE mean it's genuine audi part or is it just the equivalent? Thanks again
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  17. stu_m
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    stu_m Active Member

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    is his the B6 or the B7? and is that worked out off the DIS?

    My brother has a B7 2.0tdi and his DIS shows 55mpg average but he doesnt get that if worked out tank to tank he gets roughly the same as me 44-48 average

    OE means original equipment so audi parts the actual term is OEM (original equipment manufacturer) but every leaves the M off

    If you think you have a problem get it scanned for codes and the MAF checked too check the VCDS map for a user near you. What is your location? I'm in Hull and have VCDS if I can help
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  18. Johnjones
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    Johnjones Member

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    His is the B5 with the 115 pd engine and it was calculated by brimming the tank. I had it scanned and no codes came up except for an unidentified Ecu and aircon codes. There's no compressor in it hence those aircon codes. I'm in Bristol. Is the Maf easy to check? Thanks again.
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  19. Greeny233
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    Greeny233 Active Member

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    My 1.9tdi sport Quattro Avant does 47mpg on a long run sat at 70-80mph if I want over 50mpg I have to slow down to 60mph. 47mpg is good for such a big heavy-ish car. You could always fit a 90bhp A4 B5 engine, my old B5 used to do 50mpg everywhere and 60+mpg on the motorway.
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  20. AudidriverA4
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    AudidriverA4 Member

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    That's excellent fuel economy, there has to be something wrong with my FWD 1.9 tdi 130 bhp because I'm only getting around 40 mpg :sadlike:

    Although my car is driving perfectly and no warning lights on dash :think:
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  21. Greeny233
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    Greeny233 Active Member

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    Mine has been remapped, but I doubt that would make much difference, the biggest effect on economy is the driver. Even a Prius has to be driven economically otherwise it will only do mid 30's mpg.
    I always use Shell V Power diesel in mine rather than cheap supermarket fuel and that makes a noticeable difference. You could try some fuel system cleaner and change the fuel filter. There are lots of little things which will help with fuel economy.
    #21

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