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2011 LR4 - MPG getting worst

Discussion in 'LR4' started by djkaosone, Aug 8, 2017.

  1. djkaosone

    djkaosone '11 LR4 HSE LUX 5.0L V8

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    When I first got it, I was getting great 18-20 MPG. Then all of a sudden last year it's been averaging 12-13 MPG without the Front Runner Slimline II roof rack. 3 months ago with the roof rack, I somehow was averaging 13-14 MPG. Just recently I got 200 miles off of a full tank (18.5 gallons) or 10.8 MPG. My calculations are based on always clearing the number of miles driven on odometer A, filling up until full, and divide the number of miles driven by the number of gallons put back into it. Example, 250 miles (driven on A) divided by 18.523 gallons (filled back up) = 13.497 MPG.

    My driving habits are roughly 70-75 MPH and the foot pedal never goes past half way down to the floor. I seriously feather the pedal to hold speed or put it in cruise control. So, please save the don't drive fast comments.

    There are absolutely not warning/check engine lights, error codes, leaks, smells, or anything.

    Looking at the D4 Workshop Manual PDF on page 2584 under Excessive fuel consumption it has the following possible causes:
    • Low-pressure fuel system fault
    • Fuel volume control valve blocked/contaminated
    • Fuel pressure control valve blocked/contaminated
    • Fuel temperature sensor leak
    • High pressure fuel leak
    • Injector(s) fault
    • Exhaust gas recirculation (EGR) valve(s) fault
    I'm pretty sure if any of these are possible causes it would have tripped an error, so instead of checking everything I'm asking for some advice on what I should start at.

    I also brought it to the dealer and they told me that it'll be, forgot the exact amount, $300 for them to check it out and since it was well within specs (12-13 MPG) there's really not much they can do.

    Can someone point me in the right direction for things that I can do myself?

    Thanks!
     
  2. iSurfvilano

    iSurfvilano Full Access Member

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    Check your engine air filters.
     
  3. djkaosone

    djkaosone '11 LR4 HSE LUX 5.0L V8

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    @iSurfvilano - I installed new K&N drop-in filters, changed spark plugs out to iridiums, ran fuel injector/tank cleaners, and cleaned the maf sensors a few months ago.

    Any other suggestions? :shot:
     
  4. jhartz

    jhartz Active Member

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    Redo the MAF cleaning: the KN filters tend to gum up the MAF sensors. Clean the throttle plate and bore; check for air leaks. If you have an OBD II reader (and if you don't, get one), check for codes and fuel trims.
     
  5. djkaosone

    djkaosone '11 LR4 HSE LUX 5.0L V8

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    @jhartz - Thanks, I'll give that a try.
     
  6. jhartz

    jhartz Active Member

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    Most important: let us know what worked (or didn't); that's how we learn in this crowd sourcing process.
     
  7. djkaosone

    djkaosone '11 LR4 HSE LUX 5.0L V8

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    @jhartz - Absolutely.

    Per your recommendation, I pulled off the intake pipe to the manifold, unbolted the 4 bolts holding the TB, cleaned it out thoroughly with brake cleaner (that's what I had, I know), and reinstalled everything. You're right, there were quite a bit of grime on the back side of the TB plate. Possibly from the K&N filter oil.

    I also pulled off the left and right MAF sensors, sprayed each one down with http://www.frys.com/product/3222281 (that's what I had on hand at the moment), can air dried after 5 minutes of natural air drying, and replaced everything.

    Since I "have" to test it out, I'm driving out to Las Vegas today and will try to hit up the Afton Canyon trail off the 15 for a 14 mile off road detour. I'll let everyone know if it improved and by how much.

    So far the startup and drive is a lot smoother. Luckily I was almost empty, filled up with 91 octane (that's what we have in SD, CA) and a bottle of Seafoam SF-16. This time I got 220.9 miles and filled up 17.568 gallons, or 12.574 mpg. I'm sure I already gained at least 1 mpg back from doing the cleanup, but we'll see.
     
  8. stufrowin

    stufrowin Full Access Member

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    Interested to see as well. The TB will gunk up regardless of K&N or stock, I have K&N as well I know a lot of people are against them, I haven't noticed any benefits in the LR4 as I have with other cars but I don't think it will hurt. I Like the crc products for MAF cleaner and the intake cleaner. I'd use a can of this as well

    https://www.amazon.com/gp/aw/d/B00P..._SY340_QL65&keywords=crc+intake+turbo+cleaner

    Maybe cheaper at local auto parts store.

    My guess your intake valves are gummed too.

    Can spray straight into TB with engine running just disconnect the MAFs to avoid stalling. Likely will throw CELs as well.

    Pretty sure there is a thread on the intake cleaning. I guess should be done every 15k. I didn't know/start until 65k. Unfortunately with the direct injection fuel treatments don't help that much.
     
  9. iSurfvilano

    iSurfvilano Full Access Member

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    Why are people against them? I was considering purchasing a set.
     
  10. jhartz

    jhartz Active Member

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    They are treated with a wax-like residue that has been known to, or blamed for, gumming up the sensitive MAF sensor. Over on the Jaguar forum for the X308s, the professional techs are adamant about not using them. Now that said, I had great luck -- noticeable difference in power and gas mileage -- when I used them on a couple of BMW roadsters.

    OP: 12.5MPG is not very good. You need to have the OBD II codes read. It would also be very useful to know what the fuel trims look like.

    My RRS with the 5.0l engine routinely gets 15.8mpg around town with an average speed of 21 mph. We have 93 octane on the Right Coast; still, that shouldn't be sufficient cause for the difference. Are you running off road tires? Brakes dragging? Plugs need retorquing? Lead footed?
     
    Last edited: Aug 10, 2017

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