Dyno tuned but bad fuel consumption?

Discussion in 'Technical' started by bobbs, Dec 1, 2016.

  1. bobbs

    bobbs Member

    I'm getting about 300kms per tank (about 50L) so 17 L/km... thats a heck of a lot worse than the obese SUVs of today lol

    So a while back I had the zed professionally dyno tuned. I can't remember what its prior mileage was like. I never really took notice.

    Currently its set up with
    -AT to MT conversion
    -stock AT turbos
    -stock injectors
    -low boost is 10psi high boost at 15 always use 98 fuel
    -EBC and nistune
    -3" zorst + high flow cats and are still functional
    -larger pod style intercoolers
    -lightweight front pulley, chrome molly flywheel, ally tail shaft
    -deleted all the crap under the plenum
    -fat ally radiator, new water pump, new lifters, timing belt etc etc etc
    -wheels have been aligned, brakes aren't dragging, wheel rotate freely, wheel bearings have no play and aren't crunchy / roll smooth

    After I got it back from the tunas, I noticed it now makes black carbon deposits on the rear bar (obviously they've tuned it to be fat)

    Also just did a compression test 170~165 psi all around. Spark plugs look very clean... almost as if it was running lean.

    So do you guys get around the same fuel economy? Or is this a sign that something's broken?

    Cheers guys
     
  2. MikeZ32

    MikeZ32 das Über member

    Our tanks are 70L in size. Might get 65L or so in at each filling. Most TTs would be lucky to get around 500km out of a tank for a mix of highway and city.

    Anyways, that's around 13-14L / 100kms on average so yours isn't terrible assuming mainly city drving (start stop?)
     
  3. SrAfciGeR

    SrAfciGeR Member

    What is it tuned for performance / economy ?
     
  4. rob260

    rob260 Administrator Staff Member

    Sounds like it's running super rich.

    Oxygen sensors have probably been disabled too (no closed loop).
     
  5. MagicMike

    MagicMike Moderator Staff Member

    You can't really tune for economy or performance as cruise/idle (where you want economy) and WOT (where you want performance) are different areas of the maps.
     
  6. Anti

    Anti 14.7 x 14.7 = 44.1

    Myth
     
  7. bobbs

    bobbs Member

    Ok, so it seems my tank gauge is out of whack. When the needle hits empty, I can only fill in 55L at most... so that explains my lack of range...

    Though the consumption per distance is still pretty high. Or is this fairly normal?

    It was most likely tuned for power, temp control/quenching, knock control etc. I haven't been fouling plugs so its not that bad. Though I think one side is burning more fuel than the other bank. Result of tuning on dirty injectors maybe?
     
  8. SRB-2NV

    SRB-2NV #TEAMROB

    There's no such thing as tuning for econony or power. A good tune will have both. As magicmike said its a completely different part of the map.
     
  9. SrAfciGeR

    SrAfciGeR Member

    Ok I will correct my self :)

    You can eater:
    De-Tune the engine to lower emissions and operate smoothly over a wider RPM range. (economy)

    Or

    Tune it to increase power output (performance)
     
  10. Fists

    Fists Well-Known Member

    Not uncommon but can be improved, have a chat to the tuner and see how he'd feel about improving the cruising and low load cells and maybe whether he thinks your O2s were ok. Expect you cats to be toast in a few thousand ks if you leave it as-is.
     
  11. WazTTed

    WazTTed Grease Monkey

    do you have your dyno graphs showing the air fuel ratios?

    mines running 740 cc injectors and getting around 450 to a tank
     
  12. MagicMike

    MagicMike Moderator Staff Member

    Fuel light comes on after 60L (12L til empty).
     
  13. ltd

    ltd Linux Ninja

    Fuel tank size

    The fuel tank is indeed 72L, but I don't agree with MagicMike. The point where the fuel light comes on is 55L. This is well known.


     
  14. bobbs

    bobbs Member

    hang on... when you guys say you get 450kms to a tank... is that using 55L until the light comes on or until the fuel pump runs dry?
    So with 17L in reserve and with my current consumption, should I expect to drive another 100kms (less the little bit the pump can't pick up)? This sounds a little excessive :/
    Gotta drive back to sydney from newcastle now... I have 10L in a jerry can... so I'm tempted to see how far it goes... or I'm just assuming I'm going to cook my fuel pump :/
     
  15. Shane001

    Shane001 Well-Known Member

    lol, no offence, but it always amuses me people trying to make comparisons on subjective data. Bit like comparing dyno figures lol.

    The only way to compare fuel mileage is by writing the odometer km values at each fuel stop, recording the number of litres, and then doing a calculation.

    And TBH even this is subject to the accuracy of the fuel bowser used (of which I'm certain there are quite a few in Sydney overcharging!).

    Not to mention how, where and at what speeds it's driven.

    The fuel light may be set to come on at 55lts from factory, but this may actually be 58 lts on one car, 53 on another, 62 on another. Only way to know this would be to completely drain the tank, then fill it full, then immediately the fuel light comes on refill it. And don't forget to take into account the angle of the vehicle off horizontal.
     
  16. FireHorse

    FireHorse Member

    What is this fuel light you speak of?
    Have owned a few Zeds in the last 4 years and never once seen a fuel light and have been down below the E on several occasions... perhaps its easy to miss or often faulty?

    Aside: I use this (Android App) to track my fuel usage ... does several cars and can also track expenses

    My Cars

    I generally get 8 to 9 km/l

    [​IMG]
     
  17. Gunwarm

    Gunwarm Kamikazee Special Corps

    :rolleyes2: My fuel light works :br::zlove:
     
  18. On my cluster the fuel bowser lights up when it gets low
     
  19. Gunwarm

    Gunwarm Kamikazee Special Corps

    :D Yep that's the one :agree:
     
  20. Bob Lloyd-Jones

    Bob Lloyd-Jones Oldreverbob

    02 sensors control fuel air mix

    Check to see if your 02 sensors are working. High and low switching cycle voltages every few seconds and the heater coil in the 02 sensor are still working. If your 02 sensors are faulty you will not be able to get good fuel ecom.:zlove:
     

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