User Tag List

Results 1 to 11 of 11

Thread: Fuel Consumption

  1. Default Fuel Consumption

    Hi All,

    For some reason my fuel consumption seems to have gone up a fair amount and i can't seem to work out why.

    I would be interested in knowing how to diagnose potential causes from data logs.

    Can anyone advise on what datalogs would be best to diagnose potential fuel consumption increase causes? and what i should be looking for?

    If anyone is able to assist in interpreting logs that would be much appreciated.

    Cheers

  2. #2
    Join Date
    Apr 2010
    Location
    Canberra
    Posts
    9,459

    Default

    Get a MAF cal log:
    http://www.ozmpsclub.com/forum/showthread.php?p=289905

    Sent from my Nexus 5 using Tapatalk

  3. #3

    Default

    Vep at what @SarcasticOne says, but i would also mention a few things:

    - Has anyone else been driving the car (could be a lead foot meaning your fuel trims would have changed)
    - Have you used different fuel?
    - Perhaps the fuel you got this time around was no good...
    - Perhaps your spark plugs are needing replacement
    - Something wrong with air intake sensors (what the MAF log may show)
    - Did you re-map your ECU recently?
    - Did you take your battery out recently (ECU resets)
    - Are your tires deflated / super inflated
    - Did someone switch your wheels to 15 inch? - haha ok that was a joke.
    - Do you have a leaky BOV and are losing boost + driving hard everywhere? (the ECU will think that there is more air going back into the engine as the boost air skips the MAF sensor and will inject more petrol)
    - Perhaps you have a leaky turbo that is venting air (same as above)

    Something bizzare, but could you be super heating your air as it goes into the engine? maybe some heat shielding has come off....just thinking out loud here....

    good luck, keep us posted!

    These are the ones i can think off the top of my head
    wsDK_II
    Radiant Ebony Mazda MPS 6 (September-2007)
    My Ride: http://www.ozmpsclub.com/forum/membe...-services.html
    What is stock????

  4. #4
    Join Date
    Apr 2010
    Location
    Canberra
    Posts
    9,459

    Default

    What fuel consumption are you getting?
    What fuel do you use?
    Doing more city driving/being stuck in traffic?

    Sent from my Nexus 5 using Tapatalk

  5. Default

    Thanks for the suggestions.

    I will get a MAF cal log and post up.

    Regarding suggestions thus far:

    - Has anyone else been driving the car (could be a lead foot meaning your fuel trims would have changed)
    =>No one else touches my baby
    - Have you used different fuel?
    => No, always use BP ultimate now
    - Perhaps the fuel you got this time around was no good...
    => Perhaps although the last few fills my consumption has been consistent
    - Perhaps your spark plugs are needing replacement
    => Spark plugs replaced ~ 10k ago, I am hoping they are still fine!
    - Something wrong with air intake sensors (what the MAF log may show)
    => possible, will post log results although i changed air filter about 5k ago and cleaned MAF with MAF cleaner.
    - Did you re-map your ECU recently?
    => I did re-map a couple months ago. Fuel consumption has increased over the last few weeks for no apparent reason. I would think everything would have stabilised by now considering the car is a daily driver and i do afew 100k per week.
    - Did you take your battery out recently (ECU resets)
    => Nope
    - Are your tires deflated / super inflated
    => Check tyre pressure every couple of weeks
    - Did someone switch your wheels to 15 inch? - haha ok that was a joke.
    => Damn....you got me! (ok, thankfully not)
    - Do you have a leaky BOV and are losing boost + driving hard everywhere? (the ECU will think that there is more air going back into the engine as the boost air skips the MAF sensor and will inject more petrol)
    => I have no idea if that is the case? I should hope not as car has <100k on clock.
    - Perhaps you have a leaky turbo that is venting air (same as above)
    => same as above

    What fuel consumption are you getting?
    => Has jumped from ~11/100k to ~14/100k, thats about 25% which is a non trivial change IMO.
    What fuel do you use?
    => BP ultimate (98 ron)
    Doing more city driving/being stuck in traffic?
    => I drive same route every day. Traffic conditions are relatively consistent (within reason).

    I am somewhat stumped on this one as I can't find an obvious/logical explanation.
    Hopefully the logs provide some insight.

  6. #6

    Default

    Ok a few more questions then:

    - When you start the car, can you smell petrol / exhaust leak (you should get out of the car for this one)
    - Whilst stationary, can you smell petrol with the windows up inside the cabin?
    - Can you smell petrol whilst driving along with the windows down

    Some thoughts so far:

    - Could be the o2 sensor is failing....maybe
    - Could be failures with fuel injectors
    - Could be carbon build up on spark plugs

    Could also be:

    - Air intake leak
    - Turbo Inlet pipe leak
    - Turbo leak

    I would recommend doing the following tonight:

    - Remove all 4 spark plugs and check them against this chart: NGK Spark Plugs USA
    - Check the seals of your BOV, the Air-box -> TIP, and the TIP -> Turbo (this one is a bitch to do, might have to move the battery).
    - Do the MAF test

    Tomorrow morning, i would also do a cold start test to see if you can smell the car running rich / exhaust leak.

    Also, are you running any mods?

    Anyone else care to comment, i'm no mechanic!
    wsDK_II
    Radiant Ebony Mazda MPS 6 (September-2007)
    My Ride: http://www.ozmpsclub.com/forum/membe...-services.html
    What is stock????

  7. Default

    Quote Originally Posted by wsDKII View Post
    Ok a few more questions then:

    - When you start the car, can you smell petrol / exhaust leak (you should get out of the car for this one)
    => Thankfully not!
    - Whilst stationary, can you smell petrol with the windows up inside the cabin?
    => Thankfully not!
    - Can you smell petrol whilst driving along with the windows down
    => Thankfully not!

    Some thoughts so far:

    - Could be the o2 sensor is failing....maybe
    - Could be failures with fuel injectors
    - Could be carbon build up on spark plugs

    Could also be:

    - Air intake leak
    - Turbo Inlet pipe leak
    - Turbo leak

    I would recommend doing the following tonight:

    - Remove all 4 spark plugs and check them against this chart: NGK Spark Plugs USA
    => shall do over w/e
    - Check the seals of your BOV, the Air-box -> TIP, and the TIP -> Turbo (this one is a bitch to do, might have to move the battery).
    => ditto. I am assuming you mean a visual check of seals (i dont have any leak test equipment).
    - Do the MAF test
    => Will do this tonight hopefully.

    Tomorrow morning, i would also do a cold start test to see if you can smell the car running rich / exhaust leak.
    => what is a cold start test? do you mean just see if i can smell car running rich after cold start? If that is the case i thought most cars run rich after a cold start.

    Also, are you running any mods?
    => Car is bone stock other than OTS 98 Stage1 flash

    Anyone else care to comment, i'm no mechanic!

    On another note, looking at the MAF calibration tutorial, the bloke adds in additional break points in Cobb ATR.
    Has anyone done this before? this sounds like it would be useful.
    If so how do you add in the break points? and when you add them in do tables automatically populate with the new break points prior to driving?

    Thanks for the suggestions all.

    Cheers,
    David

  8. Default

    Hrmm i have taken some WOT logs in 3rd and 4th (though 4th is incomplete).
    I have also taken some logs for MAF calibration.
    How do i post files? do i need to upload them to an external hosting service?

  9. #9

    Default

    Hi @discodave, usually people just post them here. @SarcasticOne might be able to comment further.

    On the inspection side, how did it all go (assuming you were able to perform the tests)?

  10. Default

    Checked spark plugs, nothing out of the ordinary, all seemed fine (I was expecting that, they are quite new).
    Though I dont have any leak testers the intake piping all seemed tight and couldnt see/hear any leaks.

    Cant seem to work out how to upload files.

    My suspicion thus far is that it is sensor related.

    What are some of the common things i should be looking for that will indicate a type of failure?
    (I was reading there are ways of determining if there is an air leak etc.etc.)

    Cheers

  11. Default

    Any news?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •